feat: v2 rewrite — hexagonal arch, ActivityPub federation, NATS, deployment-ready (#1)

crates/adapters/postgres/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "postgres"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+domain           = { workspace = true }
+activitypub-base = { workspace = true }
+event-payload    = { workspace = true }
+sqlx             = { workspace = true }
+uuid        = { workspace = true }
+serde_json  = { workspace = true }
+chrono      = { workspace = true }
+async-trait = { workspace = true }
+thiserror   = { workspace = true }
+tracing     = { workspace = true }
+url         = { workspace = true }
+
+[dev-dependencies]
+tokio = { workspace = true, features = ["full"] }
+sqlx  = { workspace = true, features = ["migrate"] }

crates/adapters/postgres/migrations/001_initial_schema.sql

@@ -0,0 +1,55 @@
+CREATE EXTENSION IF NOT EXISTS "pgcrypto";
+
+CREATE TABLE IF NOT EXISTS users (
+    id           UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    username     VARCHAR(32)  NOT NULL UNIQUE,
+    email        VARCHAR(255) NOT NULL UNIQUE,
+    password_hash TEXT        NOT NULL,
+    display_name VARCHAR(50),
+    bio          VARCHAR(160),
+    avatar_url   TEXT,
+    header_url   TEXT,
+    custom_css   TEXT,
+    created_at   TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at   TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE TABLE IF NOT EXISTS thoughts (
+    id         UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    user_id    UUID        NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    content    VARCHAR(128) NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE TABLE IF NOT EXISTS follows (
+    follower_id  UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    following_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    PRIMARY KEY (follower_id, following_id)
+);
+
+CREATE TABLE IF NOT EXISTS top_friends (
+    user_id   UUID     NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    friend_id UUID     NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    position  SMALLINT NOT NULL,
+    PRIMARY KEY (user_id, friend_id),
+    UNIQUE (user_id, position)
+);
+
+CREATE TABLE IF NOT EXISTS tags (
+    id   SERIAL PRIMARY KEY,
+    name VARCHAR(50) NOT NULL UNIQUE
+);
+
+CREATE TABLE IF NOT EXISTS thought_tags (
+    thought_id UUID    NOT NULL REFERENCES thoughts(id) ON DELETE CASCADE,
+    tag_id     INTEGER NOT NULL REFERENCES tags(id) ON DELETE CASCADE,
+    PRIMARY KEY (thought_id, tag_id)
+);
+
+CREATE TABLE IF NOT EXISTS api_keys (
+    id         UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    user_id    UUID        NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    key_hash   TEXT        NOT NULL UNIQUE,
+    name       VARCHAR(50) NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);

crates/adapters/postgres/migrations/002_federation_columns.sql

@@ -0,0 +1,21 @@
+ALTER TABLE users
+    ADD COLUMN IF NOT EXISTS ap_id        TEXT UNIQUE,
+    ADD COLUMN IF NOT EXISTS inbox_url    TEXT,
+    ADD COLUMN IF NOT EXISTS public_key   TEXT,
+    ADD COLUMN IF NOT EXISTS private_key  TEXT,
+    ADD COLUMN IF NOT EXISTS local        BOOLEAN NOT NULL DEFAULT true;
+
+ALTER TABLE thoughts
+    ADD COLUMN IF NOT EXISTS in_reply_to_id  UUID REFERENCES thoughts(id),
+    ADD COLUMN IF NOT EXISTS in_reply_to_url TEXT,
+    ADD COLUMN IF NOT EXISTS ap_id           TEXT UNIQUE,
+    ADD COLUMN IF NOT EXISTS visibility      TEXT NOT NULL DEFAULT 'public',
+    ADD COLUMN IF NOT EXISTS content_warning TEXT,
+    ADD COLUMN IF NOT EXISTS sensitive       BOOLEAN NOT NULL DEFAULT false,
+    ADD COLUMN IF NOT EXISTS local           BOOLEAN NOT NULL DEFAULT true,
+    ADD COLUMN IF NOT EXISTS updated_at      TIMESTAMPTZ;
+
+ALTER TABLE follows
+    ADD COLUMN IF NOT EXISTS state      TEXT        NOT NULL DEFAULT 'accepted',
+    ADD COLUMN IF NOT EXISTS ap_id      TEXT,
+    ADD COLUMN IF NOT EXISTS created_at TIMESTAMPTZ NOT NULL DEFAULT NOW();

crates/adapters/postgres/migrations/003_new_tables.sql

@@ -0,0 +1,49 @@
+CREATE TABLE IF NOT EXISTS likes (
+    id         UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    user_id    UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    thought_id UUID NOT NULL REFERENCES thoughts(id) ON DELETE CASCADE,
+    ap_id      TEXT UNIQUE,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (user_id, thought_id)
+);
+
+CREATE TABLE IF NOT EXISTS boosts (
+    id         UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    user_id    UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    thought_id UUID NOT NULL REFERENCES thoughts(id) ON DELETE CASCADE,
+    ap_id      TEXT UNIQUE,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (user_id, thought_id)
+);
+
+CREATE TABLE IF NOT EXISTS blocks (
+    blocker_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    blocked_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    PRIMARY KEY (blocker_id, blocked_id)
+);
+
+CREATE TABLE IF NOT EXISTS remote_actors (
+    url              TEXT PRIMARY KEY,
+    handle           TEXT NOT NULL,
+    display_name     TEXT,
+    inbox_url        TEXT NOT NULL,
+    shared_inbox_url TEXT,
+    public_key       TEXT NOT NULL,
+    last_fetched_at  TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE TABLE IF NOT EXISTS notifications (
+    id           UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    user_id      UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    type         TEXT NOT NULL,
+    from_user_id UUID REFERENCES users(id) ON DELETE SET NULL,
+    thought_id   UUID REFERENCES thoughts(id) ON DELETE CASCADE,
+    read         BOOLEAN NOT NULL DEFAULT false,
+    created_at   TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_thoughts_user_id ON thoughts(user_id);
+CREATE INDEX IF NOT EXISTS idx_thoughts_created_at ON thoughts(created_at DESC);
+CREATE INDEX IF NOT EXISTS idx_follows_following_id ON follows(following_id);
+CREATE INDEX IF NOT EXISTS idx_notifications_user_id ON notifications(user_id, read);

crates/adapters/postgres/migrations/004_search_indexes.sql

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+CREATE EXTENSION IF NOT EXISTS pg_trgm;
+
+CREATE INDEX IF NOT EXISTS idx_thoughts_content_trgm
+    ON thoughts USING GIN(content gin_trgm_ops);
+
+CREATE INDEX IF NOT EXISTS idx_users_username_trgm
+    ON users USING GIN(username gin_trgm_ops);
+
+CREATE INDEX IF NOT EXISTS idx_users_display_name_trgm
+    ON users USING GIN(display_name gin_trgm_ops)
+    WHERE display_name IS NOT NULL;

crates/adapters/postgres/migrations/005_federation_tables.sql

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+-- Add avatar_url and outbox_url to remote_actors (FederationRepository::RemoteActor needs them)
+ALTER TABLE remote_actors
+    ADD COLUMN IF NOT EXISTS avatar_url  TEXT,
+    ADD COLUMN IF NOT EXISTS outbox_url  TEXT;
+
+-- Federation followers: remote actors following local users
+CREATE TABLE IF NOT EXISTS federation_followers (
+    id               UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    local_user_id    UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    remote_actor_url TEXT NOT NULL,
+    status           TEXT NOT NULL DEFAULT 'pending',
+    follow_activity_id TEXT NOT NULL,
+    created_at       TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (local_user_id, remote_actor_url)
+);
+
+-- Federation following: local users following remote actors
+CREATE TABLE IF NOT EXISTS federation_following (
+    id               UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    local_user_id    UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    remote_actor_url TEXT NOT NULL,
+    follow_activity_id TEXT NOT NULL,
+    outbox_url       TEXT,
+    created_at       TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (local_user_id, remote_actor_url)
+);
+
+-- Announces (boosts of remote objects via AP)
+CREATE TABLE IF NOT EXISTS federation_announces (
+    id           UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    activity_id  TEXT NOT NULL UNIQUE,
+    object_url   TEXT NOT NULL,
+    actor_url    TEXT NOT NULL,
+    announced_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Blocked domains (instance-level)
+CREATE TABLE IF NOT EXISTS federation_blocked_domains (
+    domain     TEXT PRIMARY KEY,
+    reason     TEXT,
+    blocked_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Blocked actors (per local user)
+CREATE TABLE IF NOT EXISTS federation_blocked_actors (
+    local_user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    actor_url     TEXT NOT NULL,
+    created_at    TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    PRIMARY KEY (local_user_id, actor_url)
+);
+
+CREATE INDEX IF NOT EXISTS idx_fed_followers_user   ON federation_followers(local_user_id);
+CREATE INDEX IF NOT EXISTS idx_fed_following_user   ON federation_following(local_user_id);
+CREATE INDEX IF NOT EXISTS idx_fed_announces_object ON federation_announces(object_url);

crates/adapters/postgres/migrations/006_remote_actor_connections.sql

@@ -0,0 +1,13 @@
+CREATE TABLE remote_actor_connections (
+    id                     UUID        PRIMARY KEY DEFAULT gen_random_uuid(),
+    actor_url              TEXT        NOT NULL,
+    connection_type        TEXT        NOT NULL,
+    page                   INT         NOT NULL,
+    connected_actor_url    TEXT        NOT NULL,
+    connected_handle       TEXT        NOT NULL,
+    connected_display_name TEXT,
+    connected_avatar_url   TEXT,
+    fetched_at             TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE(actor_url, connection_type, page, connected_actor_url)
+);
+CREATE INDEX ON remote_actor_connections(actor_url, connection_type, page, fetched_at);

crates/adapters/postgres/migrations/007_content_text.sql

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+-- Remote ActivityPub posts can exceed 128 characters.
+-- The 128-char limit is enforced at the application layer for local posts only.
+ALTER TABLE thoughts ALTER COLUMN content TYPE TEXT;

crates/adapters/postgres/migrations/008_rename_notifications_type.sql

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+ALTER TABLE notifications RENAME COLUMN "type" TO notification_type;

crates/adapters/postgres/migrations/009_failed_events.sql

@@ -0,0 +1,15 @@
+CREATE TABLE failed_events (
+    id           UUID        NOT NULL DEFAULT gen_random_uuid(),
+    event_type   TEXT        NOT NULL,
+    payload      JSONB       NOT NULL,
+    failed_at    TIMESTAMPTZ NOT NULL DEFAULT now(),
+    retry_at     TIMESTAMPTZ NOT NULL,
+    retry_count  INT         NOT NULL DEFAULT 0,
+    last_error   TEXT        NOT NULL,
+
+    CONSTRAINT failed_events_pkey PRIMARY KEY (id)
+);
+
+CREATE INDEX failed_events_due_idx
+    ON failed_events (retry_at)
+    WHERE retry_count < 3;

crates/adapters/postgres/migrations/010_fix_reply_fk_on_delete.sql

@@ -0,0 +1,11 @@
+-- Change in_reply_to_id FK from RESTRICT (default) to SET NULL.
+-- Previously, deleting a thought that had replies raised a FK violation.
+-- With SET NULL, deleting a thought orphans its replies (they survive but
+-- lose their parent reference), which is the correct semantic for a
+-- threaded social app.
+ALTER TABLE thoughts
+    DROP CONSTRAINT IF EXISTS thoughts_in_reply_to_id_fkey;
+
+ALTER TABLE thoughts
+    ADD CONSTRAINT thoughts_in_reply_to_id_fkey
+    FOREIGN KEY (in_reply_to_id) REFERENCES thoughts(id) ON DELETE SET NULL;

crates/adapters/postgres/migrations/011_outbox_events.sql

@@ -0,0 +1,10 @@
+CREATE TABLE outbox_events (
+    seq          BIGSERIAL   PRIMARY KEY,
+    aggregate_id UUID        NOT NULL,
+    event_type   TEXT        NOT NULL,
+    payload      JSONB       NOT NULL,
+    created_at   TIMESTAMPTZ NOT NULL DEFAULT now(),
+    delivered    BOOLEAN     NOT NULL DEFAULT false,
+    delivered_at TIMESTAMPTZ
+);
+CREATE INDEX outbox_events_pending_idx ON outbox_events (seq) WHERE delivered = false;

crates/adapters/postgres/src/activitypub.rs

@@ -0,0 +1,406 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+
+const MAX_REMOTE_CONTENT_CHARS: usize = 500;
+const THOUGHTS_PATH_PREFIX: &str = "/thoughts/";
+use chrono::{DateTime, Utc};
+use sqlx::PgPool;
+
+use activitypub_base::{ActivityPubRepository, ActorApUrls, OutboxEntry};
+use domain::{
+    errors::DomainError,
+    models::thought::{Thought, Visibility},
+    value_objects::{Content, ThoughtId, UserId, Username},
+};
+
+pub struct PgActivityPubRepository {
+    pool: PgPool,
+}
+
+impl PgActivityPubRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl ActivityPubRepository for PgActivityPubRepository {
+    async fn outbox_entries_for_actor(
+        &self,
+        user_id: &UserId,
+    ) -> Result<Vec<OutboxEntry>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            id: uuid::Uuid,
+            user_id: uuid::Uuid,
+            content: String,
+            created_at: DateTime<Utc>,
+            in_reply_to_id: Option<uuid::Uuid>,
+            content_warning: Option<String>,
+            sensitive: bool,
+            username: String,
+            updated_at: Option<DateTime<Utc>>,
+        }
+        sqlx::query_as::<_, Row>(
+            "SELECT t.id, t.user_id, t.content, t.created_at, t.in_reply_to_id, t.content_warning, t.sensitive, u.username, t.updated_at
+             FROM thoughts t JOIN users u ON u.id=t.user_id
+             WHERE t.user_id=$1 AND t.local=true AND t.visibility='public'
+             ORDER BY t.created_at DESC",
+        )
+        .bind(user_id.as_uuid())
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()
+        .map(|rows| {
+            rows.into_iter()
+                .map(|r| OutboxEntry {
+                    thought: Thought {
+                        id: ThoughtId::from_uuid(r.id),
+                        user_id: UserId::from_uuid(r.user_id),
+                        content: Content::new_remote(r.content),
+                        in_reply_to_id: r.in_reply_to_id.map(ThoughtId::from_uuid),
+                        visibility: Visibility::Public,
+                        content_warning: r.content_warning,
+                        sensitive: r.sensitive,
+                        local: true,
+                        created_at: r.created_at,
+                        updated_at: r.updated_at,
+                    },
+                    author_username: Username::from_trusted(r.username),
+                })
+                .collect()
+        })
+    }
+
+    async fn outbox_page_for_actor(
+        &self,
+        user_id: &UserId,
+        before: Option<DateTime<Utc>>,
+        limit: usize,
+    ) -> Result<Vec<OutboxEntry>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            id: uuid::Uuid,
+            user_id: uuid::Uuid,
+            content: String,
+            created_at: DateTime<Utc>,
+            in_reply_to_id: Option<uuid::Uuid>,
+            content_warning: Option<String>,
+            sensitive: bool,
+            username: String,
+            updated_at: Option<DateTime<Utc>>,
+        }
+        let rows = if let Some(before) = before {
+            sqlx::query_as::<_, Row>(
+                "SELECT t.id, t.user_id, t.content, t.created_at, t.in_reply_to_id, t.content_warning, t.sensitive, u.username, t.updated_at
+                 FROM thoughts t JOIN users u ON u.id=t.user_id
+                 WHERE t.user_id=$1 AND t.local=true AND t.visibility='public' AND t.created_at < $2
+                 ORDER BY t.created_at DESC LIMIT $3",
+            )
+            .bind(user_id.as_uuid())
+            .bind(before)
+            .bind(limit as i64)
+            .fetch_all(&self.pool)
+            .await
+        } else {
+            sqlx::query_as::<_, Row>(
+                "SELECT t.id, t.user_id, t.content, t.created_at, t.in_reply_to_id, t.content_warning, t.sensitive, u.username, t.updated_at
+                 FROM thoughts t JOIN users u ON u.id=t.user_id
+                 WHERE t.user_id=$1 AND t.local=true AND t.visibility='public'
+                 ORDER BY t.created_at DESC LIMIT $2",
+            )
+            .bind(user_id.as_uuid())
+            .bind(limit as i64)
+            .fetch_all(&self.pool)
+            .await
+        }
+        .into_domain()?;
+
+        Ok(rows
+            .into_iter()
+            .map(|r| OutboxEntry {
+                thought: Thought {
+                    id: ThoughtId::from_uuid(r.id),
+                    user_id: UserId::from_uuid(r.user_id),
+                    content: Content::new_remote(r.content),
+                    in_reply_to_id: r.in_reply_to_id.map(ThoughtId::from_uuid),
+                    visibility: Visibility::Public,
+                    content_warning: r.content_warning,
+                    sensitive: r.sensitive,
+                    local: true,
+                    created_at: r.created_at,
+                    updated_at: r.updated_at,
+                },
+                author_username: Username::from_trusted(r.username),
+            })
+            .collect())
+    }
+
+    async fn find_remote_actor_id(
+        &self,
+        actor_ap_url: &str,
+    ) -> Result<Option<UserId>, DomainError> {
+        sqlx::query_scalar::<_, uuid::Uuid>("SELECT id FROM users WHERE ap_id=$1")
+            .bind(actor_ap_url)
+            .fetch_optional(&self.pool)
+            .await
+            .into_domain()
+            .map(|o| o.map(UserId::from_uuid))
+    }
+
+    async fn intern_remote_actor(&self, actor_ap_url: &str) -> Result<UserId, DomainError> {
+        if let Some(id) = self.find_remote_actor_id(actor_ap_url).await? {
+            return Ok(id);
+        }
+        let new_id = uuid::Uuid::new_v4();
+        // Use the last path segment as username (e.g. /users/alice → "alice").
+        // Falls back to a random short id for long segments (e.g. UUID-based actor URLs).
+        // username column is VARCHAR(32).
+        let last_seg = url::Url::parse(actor_ap_url)
+            .ok()
+            .and_then(|u| {
+                u.path_segments()
+                    .and_then(|mut s| s.next_back().map(|s| s.to_string()))
+            })
+            .unwrap_or_default();
+        let handle = if last_seg.is_empty() {
+            format!("remote_{}", &new_id.to_string()[..13])
+        } else if last_seg.len() <= 32 {
+            last_seg
+        } else {
+            format!("remote_{}", &new_id.to_string()[..13])
+        };
+        sqlx::query(
+            "INSERT INTO users(id,username,email,password_hash,local,ap_id,created_at,updated_at)
+             VALUES($1,$2,$3,'',false,$4,NOW(),NOW()) ON CONFLICT(ap_id) DO NOTHING",
+        )
+        .bind(new_id)
+        .bind(&handle)
+        .bind(format!("{}@remote", new_id))
+        .bind(actor_ap_url)
+        .execute(&self.pool)
+        .await
+        .into_domain()?;
+        // Re-fetch to get whichever id won the race
+        self.find_remote_actor_id(actor_ap_url)
+            .await?
+            .ok_or_else(|| {
+                DomainError::Internal(
+                    "intern_remote_actor: insert succeeded but row not found".into(),
+                )
+            })
+    }
+
+    async fn update_remote_actor_display(
+        &self,
+        user_id: &UserId,
+        display_name: Option<&str>,
+        avatar_url: Option<&str>,
+    ) -> Result<(), DomainError> {
+        sqlx::query(
+            "UPDATE users SET display_name=$1, avatar_url=$2, updated_at=NOW()
+             WHERE id=$3 AND local=false",
+        )
+        .bind(display_name)
+        .bind(avatar_url)
+        .bind(user_id.as_uuid())
+        .execute(&self.pool)
+        .await
+        .into_domain()
+        .map(|_| ())
+    }
+
+    async fn accept_note(
+        &self,
+        ap_id: &str,
+        author_id: &UserId,
+        content: &str,
+        published: DateTime<Utc>,
+        sensitive: bool,
+        content_warning: Option<String>,
+        visibility: &str,
+        in_reply_to: Option<&str>,
+    ) -> Result<ThoughtId, DomainError> {
+        let capped: String = content.chars().take(MAX_REMOTE_CONTENT_CHARS).collect();
+        let (in_reply_to_id, in_reply_to_url) = match in_reply_to {
+            Some(url) => {
+                // If the parent is a local thought, extract its UUID for in_reply_to_id.
+                let local_uuid = url::Url::parse(url).ok().and_then(|u| {
+                    u.path()
+                        .strip_prefix(THOUGHTS_PATH_PREFIX)
+                        .and_then(|s| s.split('/').next())
+                        .and_then(|s| uuid::Uuid::parse_str(s).ok())
+                });
+                (local_uuid, Some(url.to_string()))
+            }
+            None => (None, None),
+        };
+        sqlx::query(
+            "INSERT INTO thoughts(id,user_id,content,ap_id,visibility,sensitive,local,content_warning,created_at,in_reply_to_id,in_reply_to_url)
+             VALUES($1,$2,$3,$4,$8,$5,false,$6,$7,$9,$10) ON CONFLICT(ap_id) DO NOTHING",
+        )
+        .bind(uuid::Uuid::new_v4())
+        .bind(author_id.as_uuid())
+        .bind(&capped)
+        .bind(ap_id)
+        .bind(sensitive)
+        .bind(content_warning)
+        .bind(published)
+        .bind(visibility)
+        .bind(in_reply_to_id)
+        .bind(&in_reply_to_url)
+        .execute(&self.pool)
+        .await
+        .into_domain()?;
+
+        // SELECT the id — works whether the INSERT was a no-op or not (idempotent).
+        let row: (uuid::Uuid,) =
+            sqlx::query_as("SELECT id FROM thoughts WHERE ap_id=$1")
+                .bind(ap_id)
+                .fetch_one(&self.pool)
+                .await
+                .into_domain()?;
+        Ok(ThoughtId::from_uuid(row.0))
+    }
+
+    async fn apply_note_update(&self, ap_id: &str, new_content: &str) -> Result<(), DomainError> {
+        let capped: String = new_content.chars().take(MAX_REMOTE_CONTENT_CHARS).collect();
+        sqlx::query(
+            "UPDATE thoughts SET content=$2,updated_at=NOW() WHERE ap_id=$1 AND local=false",
+        )
+        .bind(ap_id)
+        .bind(&capped)
+        .execute(&self.pool)
+        .await
+        .into_domain()
+        .map(|_| ())
+    }
+
+    async fn retract_note(&self, ap_id: &str) -> Result<(), DomainError> {
+        sqlx::query("DELETE FROM thoughts WHERE ap_id=$1 AND local=false")
+            .bind(ap_id)
+            .execute(&self.pool)
+            .await
+            .into_domain()
+            .map(|_| ())
+    }
+
+    async fn retract_actor_notes(&self, actor_ap_url: &str) -> Result<(), DomainError> {
+        sqlx::query(
+            "DELETE FROM thoughts WHERE local=false AND user_id=(SELECT id FROM users WHERE ap_id=$1)",
+        )
+        .bind(actor_ap_url)
+        .execute(&self.pool)
+        .await
+        .into_domain()
+        .map(|_| ())
+    }
+
+    async fn count_local_notes(&self) -> Result<u64, DomainError> {
+        let n: i64 = sqlx::query_scalar("SELECT COUNT(*) FROM thoughts WHERE local=true")
+            .fetch_one(&self.pool)
+            .await
+            .into_domain()?;
+        Ok(n as u64)
+    }
+
+    async fn get_thought_ap_id(
+        &self,
+        thought_id: &ThoughtId,
+    ) -> Result<Option<String>, DomainError> {
+        sqlx::query_scalar::<_, String>(
+            "SELECT ap_id FROM thoughts WHERE id = $1 AND ap_id IS NOT NULL",
+        )
+        .bind(thought_id.as_uuid())
+        .fetch_optional(&self.pool)
+        .await
+        .into_domain()
+    }
+
+    async fn get_actor_ap_urls(
+        &self,
+        user_id: &UserId,
+    ) -> Result<Option<ActorApUrls>, DomainError> {
+        sqlx::query_as::<_, (String, String)>(
+            "SELECT ap_id, inbox_url FROM users \
+             WHERE id = $1 AND ap_id IS NOT NULL AND inbox_url IS NOT NULL",
+        )
+        .bind(user_id.as_uuid())
+        .fetch_optional(&self.pool)
+        .await
+        .into_domain()
+        .map(|opt| opt.map(|(ap_id, inbox_url)| ActorApUrls { ap_id, inbox_url }))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use activitypub_base::ActivityPubRepository;
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn intern_remote_actor_is_idempotent(pool: sqlx::PgPool) {
+        let repo = PgActivityPubRepository::new(pool);
+        let url = "https://mastodon.social/users/alice";
+        let id1 = repo.intern_remote_actor(url).await.unwrap();
+        let id2 = repo.intern_remote_actor(url).await.unwrap();
+        assert_eq!(id1, id2);
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn accept_and_retract_note(pool: sqlx::PgPool) {
+        let repo = PgActivityPubRepository::new(pool);
+        let actor_url = "https://remote.example/users/bob";
+        let ap_id = "https://remote.example/notes/1";
+        let author = repo.intern_remote_actor(actor_url).await.unwrap();
+        repo.accept_note(
+            ap_id,
+            &author,
+            "hello from remote",
+            chrono::Utc::now(),
+            false,
+            None,
+            "public",
+            None,
+        )
+        .await
+        .unwrap();
+        repo.retract_note(ap_id).await.unwrap();
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn count_local_notes_excludes_remote(pool: sqlx::PgPool) {
+        let repo = PgActivityPubRepository::new(pool);
+        assert_eq!(repo.count_local_notes().await.unwrap(), 0);
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn accept_note_returns_thought_id(pool: sqlx::PgPool) {
+        let repo = PgActivityPubRepository::new(pool.clone());
+        let actor_user_id = repo
+            .intern_remote_actor("https://remote.example/users/alice")
+            .await
+            .unwrap();
+
+        let thought_id = repo
+            .accept_note(
+                "https://remote.example/notes/1",
+                &actor_user_id,
+                "Hello #rust world",
+                chrono::Utc::now(),
+                false,
+                None,
+                "public",
+                None,
+            )
+            .await
+            .unwrap();
+
+        let row: (uuid::Uuid,) = sqlx::query_as("SELECT id FROM thoughts WHERE ap_id=$1")
+            .bind("https://remote.example/notes/1")
+            .fetch_one(&pool)
+            .await
+            .unwrap();
+        assert_eq!(thought_id.as_uuid(), row.0);
+    }
+}

crates/adapters/postgres/src/api_key.rs

@@ -0,0 +1,142 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use chrono::{DateTime, Utc};
+use domain::{
+    errors::DomainError,
+    models::api_key::ApiKey,
+    ports::ApiKeyRepository,
+    value_objects::{ApiKeyId, UserId},
+};
+use sqlx::PgPool;
+
+pub struct PgApiKeyRepository {
+    pool: PgPool,
+}
+impl PgApiKeyRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl ApiKeyRepository for PgApiKeyRepository {
+    async fn save(&self, k: &ApiKey) -> Result<(), DomainError> {
+        sqlx::query(
+            "INSERT INTO api_keys(id,user_id,key_hash,name,created_at) VALUES($1,$2,$3,$4,$5)",
+        )
+        .bind(k.id.as_uuid())
+        .bind(k.user_id.as_uuid())
+        .bind(&k.key_hash)
+        .bind(&k.name)
+        .bind(k.created_at)
+        .execute(&self.pool)
+        .await
+        .into_domain()
+        .map(|_| ())
+    }
+
+    async fn find_by_hash(&self, hash: &str) -> Result<Option<ApiKey>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            id: uuid::Uuid,
+            user_id: uuid::Uuid,
+            key_hash: String,
+            name: String,
+            created_at: DateTime<Utc>,
+        }
+        sqlx::query_as::<_, Row>(
+            "SELECT id,user_id,key_hash,name,created_at FROM api_keys WHERE key_hash=$1",
+        )
+        .bind(hash)
+        .fetch_optional(&self.pool)
+        .await
+        .into_domain()
+        .map(|o| {
+            o.map(|r| ApiKey {
+                id: ApiKeyId::from_uuid(r.id),
+                user_id: UserId::from_uuid(r.user_id),
+                key_hash: r.key_hash,
+                name: r.name,
+                created_at: r.created_at,
+            })
+        })
+    }
+
+    async fn list_for_user(&self, user_id: &UserId) -> Result<Vec<ApiKey>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            id: uuid::Uuid,
+            user_id: uuid::Uuid,
+            key_hash: String,
+            name: String,
+            created_at: DateTime<Utc>,
+        }
+        sqlx::query_as::<_, Row>("SELECT id,user_id,key_hash,name,created_at FROM api_keys WHERE user_id=$1 ORDER BY created_at DESC")
+            .bind(user_id.as_uuid()).fetch_all(&self.pool).await
+            .into_domain()
+            .map(|rows| rows.into_iter().map(|r| ApiKey { id: ApiKeyId::from_uuid(r.id), user_id: UserId::from_uuid(r.user_id), key_hash: r.key_hash, name: r.name, created_at: r.created_at }).collect())
+    }
+
+    async fn delete(&self, id: &ApiKeyId, user_id: &UserId) -> Result<(), DomainError> {
+        sqlx::query("DELETE FROM api_keys WHERE id=$1 AND user_id=$2")
+            .bind(id.as_uuid())
+            .bind(user_id.as_uuid())
+            .execute(&self.pool)
+            .await
+            .into_domain()
+            .map(|_| ())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::user::PgUserRepository;
+    use chrono::Utc;
+    use domain::ports::UserWriter;
+    use domain::{models::user::User, value_objects::*};
+
+    async fn seed_user(pool: &sqlx::PgPool) -> User {
+        let repo = PgUserRepository::new(pool.clone());
+        let u = User::new_local(
+            UserId::new(),
+            Username::new("alice").unwrap(),
+            Email::new("alice@ex.com").unwrap(),
+            PasswordHash("h".into()),
+        );
+        repo.save(&u).await.unwrap();
+        u
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn save_and_find_by_hash(pool: sqlx::PgPool) {
+        let user = seed_user(&pool).await;
+        let repo = PgApiKeyRepository::new(pool);
+        let key = ApiKey {
+            id: ApiKeyId::new(),
+            user_id: user.id.clone(),
+            key_hash: "abc123".into(),
+            name: "test".into(),
+            created_at: Utc::now(),
+        };
+        repo.save(&key).await.unwrap();
+        let found = repo.find_by_hash("abc123").await.unwrap().unwrap();
+        assert_eq!(found.name, "test");
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn delete_key(pool: sqlx::PgPool) {
+        let user = seed_user(&pool).await;
+        let repo = PgApiKeyRepository::new(pool);
+        let key = ApiKey {
+            id: ApiKeyId::new(),
+            user_id: user.id.clone(),
+            key_hash: "def456".into(),
+            name: "key2".into(),
+            created_at: Utc::now(),
+        };
+        repo.save(&key).await.unwrap();
+        repo.delete(&key.id, &user.id).await.unwrap();
+        assert!(repo.find_by_hash("def456").await.unwrap().is_none());
+    }
+}

crates/adapters/postgres/src/block.rs

@@ -0,0 +1,90 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use domain::{
+    errors::DomainError, models::social::Block, ports::BlockRepository, value_objects::UserId,
+};
+use sqlx::PgPool;
+
+pub struct PgBlockRepository {
+    pool: PgPool,
+}
+impl PgBlockRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl BlockRepository for PgBlockRepository {
+    async fn save(&self, b: &Block) -> Result<(), DomainError> {
+        sqlx::query(
+            "INSERT INTO blocks(blocker_id,blocked_id,created_at) VALUES($1,$2,$3) ON CONFLICT DO NOTHING"
+        )
+        .bind(b.blocker_id.as_uuid())
+        .bind(b.blocked_id.as_uuid())
+        .bind(b.created_at)
+        .execute(&self.pool)
+        .await
+        .into_domain()
+        .map(|_| ())
+    }
+
+    async fn delete(&self, blocker_id: &UserId, blocked_id: &UserId) -> Result<(), DomainError> {
+        sqlx::query("DELETE FROM blocks WHERE blocker_id=$1 AND blocked_id=$2")
+            .bind(blocker_id.as_uuid())
+            .bind(blocked_id.as_uuid())
+            .execute(&self.pool)
+            .await
+            .into_domain()
+            .map(|_| ())
+    }
+
+    async fn exists(&self, blocker_id: &UserId, blocked_id: &UserId) -> Result<bool, DomainError> {
+        let count: i64 =
+            sqlx::query_scalar("SELECT COUNT(*) FROM blocks WHERE blocker_id=$1 AND blocked_id=$2")
+                .bind(blocker_id.as_uuid())
+                .bind(blocked_id.as_uuid())
+                .fetch_one(&self.pool)
+                .await
+                .into_domain()?;
+        Ok(count > 0)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_helpers::seed_user;
+    use chrono::Utc;
+    use domain::value_objects::*;
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn block_exists(pool: sqlx::PgPool) {
+        let alice = seed_user(&pool, "alice", "alice@ex.com").await;
+        let bob = seed_user(&pool, "bob", "bob@ex.com").await;
+        let repo = PgBlockRepository::new(pool);
+        let block = Block {
+            blocker_id: alice.id.clone(),
+            blocked_id: bob.id.clone(),
+            created_at: Utc::now(),
+        };
+        repo.save(&block).await.unwrap();
+        assert!(repo.exists(&alice.id, &bob.id).await.unwrap());
+        assert!(!repo.exists(&bob.id, &alice.id).await.unwrap());
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn unblock(pool: sqlx::PgPool) {
+        let alice = seed_user(&pool, "alice", "alice@ex.com").await;
+        let bob = seed_user(&pool, "bob", "bob@ex.com").await;
+        let repo = PgBlockRepository::new(pool);
+        let block = Block {
+            blocker_id: alice.id.clone(),
+            blocked_id: bob.id.clone(),
+            created_at: Utc::now(),
+        };
+        repo.save(&block).await.unwrap();
+        repo.delete(&alice.id, &bob.id).await.unwrap();
+        assert!(!repo.exists(&alice.id, &bob.id).await.unwrap());
+    }
+}

crates/adapters/postgres/src/boost.rs

@@ -0,0 +1,110 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use chrono::{DateTime, Utc};
+use domain::{
+    errors::DomainError,
+    models::social::Boost,
+    ports::BoostRepository,
+    value_objects::{BoostId, ThoughtId, UserId},
+};
+use sqlx::PgPool;
+
+pub struct PgBoostRepository {
+    pool: PgPool,
+}
+impl PgBoostRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl BoostRepository for PgBoostRepository {
+    async fn save(&self, b: &Boost) -> Result<(), DomainError> {
+        sqlx::query(
+            "INSERT INTO boosts(id,user_id,thought_id,ap_id,created_at) VALUES($1,$2,$3,$4,$5) ON CONFLICT(user_id,thought_id) DO NOTHING"
+        )
+        .bind(b.id.as_uuid()).bind(b.user_id.as_uuid()).bind(b.thought_id.as_uuid()).bind(&b.ap_id).bind(b.created_at)
+        .execute(&self.pool).await.into_domain().map(|_| ())
+    }
+
+    async fn delete(&self, user_id: &UserId, thought_id: &ThoughtId) -> Result<(), DomainError> {
+        let r = sqlx::query("DELETE FROM boosts WHERE user_id=$1 AND thought_id=$2")
+            .bind(user_id.as_uuid())
+            .bind(thought_id.as_uuid())
+            .execute(&self.pool)
+            .await
+            .into_domain()?;
+        if r.rows_affected() == 0 {
+            return Err(DomainError::NotFound);
+        }
+        Ok(())
+    }
+
+    async fn find(
+        &self,
+        user_id: &UserId,
+        thought_id: &ThoughtId,
+    ) -> Result<Option<Boost>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            id: uuid::Uuid,
+            user_id: uuid::Uuid,
+            thought_id: uuid::Uuid,
+            ap_id: Option<String>,
+            created_at: DateTime<Utc>,
+        }
+        sqlx::query_as::<_, Row>("SELECT id,user_id,thought_id,ap_id,created_at FROM boosts WHERE user_id=$1 AND thought_id=$2")
+            .bind(user_id.as_uuid()).bind(thought_id.as_uuid())
+            .fetch_optional(&self.pool).await
+            .into_domain()
+            .map(|o| o.map(|r| Boost { id: BoostId::from_uuid(r.id), user_id: UserId::from_uuid(r.user_id), thought_id: ThoughtId::from_uuid(r.thought_id), ap_id: r.ap_id, created_at: r.created_at }))
+    }
+
+    async fn count_for_thought(&self, thought_id: &ThoughtId) -> Result<i64, DomainError> {
+        sqlx::query_scalar("SELECT COUNT(*) FROM boosts WHERE thought_id=$1")
+            .bind(thought_id.as_uuid())
+            .fetch_one(&self.pool)
+            .await
+            .into_domain()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_helpers::seed_user_and_thought;
+    use chrono::Utc;
+    use domain::value_objects::*;
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn boost_and_count(pool: sqlx::PgPool) {
+        let (user, thought) = seed_user_and_thought(&pool).await;
+        let repo = PgBoostRepository::new(pool);
+        let boost = Boost {
+            id: BoostId::new(),
+            user_id: user.id.clone(),
+            thought_id: thought.id.clone(),
+            ap_id: None,
+            created_at: Utc::now(),
+        };
+        repo.save(&boost).await.unwrap();
+        assert_eq!(repo.count_for_thought(&thought.id).await.unwrap(), 1);
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn unboost(pool: sqlx::PgPool) {
+        let (user, thought) = seed_user_and_thought(&pool).await;
+        let repo = PgBoostRepository::new(pool);
+        let boost = Boost {
+            id: BoostId::new(),
+            user_id: user.id.clone(),
+            thought_id: thought.id.clone(),
+            ap_id: None,
+            created_at: Utc::now(),
+        };
+        repo.save(&boost).await.unwrap();
+        repo.delete(&user.id, &thought.id).await.unwrap();
+        assert_eq!(repo.count_for_thought(&thought.id).await.unwrap(), 0);
+    }
+}

crates/adapters/postgres/src/db_error.rs

@@ -0,0 +1,20 @@
+use domain::errors::DomainError;
+
+pub(crate) trait IntoDbResult<T> {
+    fn into_domain(self) -> Result<T, DomainError>;
+}
+
+impl<T> IntoDbResult<T> for Result<T, sqlx::Error> {
+    fn into_domain(self) -> Result<T, DomainError> {
+        self.map_err(|e| {
+            if let sqlx::Error::Database(ref db) = e {
+                if db.code().as_deref() == Some("23505") {
+                    return DomainError::Conflict(
+                        db.constraint().unwrap_or("conflict").to_string(),
+                    );
+                }
+            }
+            DomainError::Internal(e.to_string())
+        })
+    }
+}

crates/adapters/postgres/src/engagement.rs

@@ -0,0 +1,83 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use domain::{
+    errors::DomainError,
+    models::feed::{EngagementStats, ViewerContext},
+    ports::EngagementRepository,
+    value_objects::{ThoughtId, UserId},
+};
+use sqlx::PgPool;
+use std::collections::HashMap;
+
+pub struct PgEngagementRepository {
+    pool: PgPool,
+}
+
+impl PgEngagementRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl EngagementRepository for PgEngagementRepository {
+    async fn get_for_thoughts(
+        &self,
+        thought_ids: &[ThoughtId],
+        viewer_id: Option<&UserId>,
+    ) -> Result<HashMap<ThoughtId, (EngagementStats, Option<ViewerContext>)>, DomainError> {
+        if thought_ids.is_empty() {
+            return Ok(HashMap::new());
+        }
+
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            thought_id: uuid::Uuid,
+            like_count: i64,
+            boost_count: i64,
+            reply_count: i64,
+            liked_by_viewer: bool,
+            boosted_by_viewer: bool,
+        }
+
+        let ids: Vec<uuid::Uuid> = thought_ids.iter().map(|t| t.as_uuid()).collect();
+        let viewer_uuid: Option<uuid::Uuid> = viewer_id.map(|v| v.as_uuid());
+
+        let rows = sqlx::query_as::<_, Row>(
+            "SELECT
+                t.id AS thought_id,
+                COUNT(DISTINCT l.user_id) AS like_count,
+                COUNT(DISTINCT b.user_id) AS boost_count,
+                COUNT(DISTINCT r.id) AS reply_count,
+                COALESCE(BOOL_OR(l.user_id = $2), false) AS liked_by_viewer,
+                COALESCE(BOOL_OR(b.user_id = $2), false) AS boosted_by_viewer
+             FROM thoughts t
+             LEFT JOIN likes l ON l.thought_id = t.id
+             LEFT JOIN boosts b ON b.thought_id = t.id
+             LEFT JOIN thoughts r ON r.in_reply_to_id = t.id
+             WHERE t.id = ANY($1)
+             GROUP BY t.id",
+        )
+        .bind(&ids[..])
+        .bind(viewer_uuid)
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()?;
+
+        let mut result = HashMap::new();
+        for row in rows {
+            let tid = ThoughtId::from_uuid(row.thought_id);
+            let stats = EngagementStats {
+                like_count: row.like_count,
+                boost_count: row.boost_count,
+                reply_count: row.reply_count,
+            };
+            let viewer = viewer_id.map(|_| ViewerContext {
+                liked: row.liked_by_viewer,
+                boosted: row.boosted_by_viewer,
+            });
+            result.insert(tid, (stats, viewer));
+        }
+        Ok(result)
+    }
+}

crates/adapters/postgres/src/failed_event.rs

@@ -0,0 +1,105 @@
+use chrono::{DateTime, Utc};
+use sqlx::PgPool;
+
+/// How many times a failed event is retried by the DLQ processor.
+pub const DLQ_MAX_RETRIES: i32 = 3;
+/// Quarantine period for the first DLQ retry (seconds). Doubles each retry.
+pub const DLQ_INITIAL_BACKOFF_SECS: i64 = 300; // 5 minutes
+/// How often the DLQ processor polls for due retries (seconds).
+pub const DLQ_POLL_INTERVAL_SECS: u64 = 60;
+
+#[derive(sqlx::FromRow)]
+pub struct FailedEvent {
+    pub id: uuid::Uuid,
+    pub event_type: String,
+    pub payload: serde_json::Value,
+    pub failed_at: DateTime<Utc>,
+    pub retry_at: DateTime<Utc>,
+    pub retry_count: i32,
+    pub last_error: String,
+}
+
+pub struct PgFailedEventStore {
+    pool: PgPool,
+}
+
+impl PgFailedEventStore {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+
+    /// Insert a newly exhausted event into the DLQ.
+    pub async fn insert(
+        &self,
+        event_type: &str,
+        payload: &serde_json::Value,
+        last_error: &str,
+    ) -> Result<(), sqlx::Error> {
+        let retry_at = Utc::now() + chrono::Duration::seconds(DLQ_INITIAL_BACKOFF_SECS);
+        sqlx::query(
+            "INSERT INTO failed_events \
+             (event_type, payload, retry_at, last_error) \
+             VALUES ($1, $2, $3, $4)",
+        )
+        .bind(event_type)
+        .bind(payload)
+        .bind(retry_at)
+        .bind(last_error)
+        .execute(&self.pool)
+        .await?;
+        Ok(())
+    }
+
+    /// Fetch all events due for retry (retry_at <= now, retry_count < DLQ_MAX_RETRIES).
+    pub async fn poll_due(&self) -> Result<Vec<FailedEvent>, sqlx::Error> {
+        sqlx::query_as::<_, FailedEvent>(
+            "SELECT id, event_type, payload, failed_at, retry_at, retry_count, last_error \
+             FROM failed_events \
+             WHERE retry_at <= now() AND retry_count < $1 \
+             ORDER BY retry_at \
+             LIMIT 100",
+        )
+        .bind(DLQ_MAX_RETRIES)
+        .fetch_all(&self.pool)
+        .await
+    }
+
+    /// Advance a row after a republish attempt using exponential backoff.
+    /// next_retry = now + initial * 2^retry_count
+    pub async fn advance(&self, id: uuid::Uuid, error: Option<&str>) -> Result<(), sqlx::Error> {
+        let current: i32 =
+            sqlx::query_scalar("SELECT retry_count FROM failed_events WHERE id = $1")
+                .bind(id)
+                .fetch_one(&self.pool)
+                .await?;
+
+        let new_count = current + 1;
+        let backoff_secs = DLQ_INITIAL_BACKOFF_SECS * (1_i64 << new_count.min(10));
+        let retry_at = Utc::now() + chrono::Duration::seconds(backoff_secs);
+        let last_error = error.unwrap_or("republish succeeded");
+
+        sqlx::query(
+            "UPDATE failed_events \
+             SET retry_count = $1, retry_at = $2, last_error = $3 \
+             WHERE id = $4",
+        )
+        .bind(new_count)
+        .bind(retry_at)
+        .bind(last_error)
+        .bind(id)
+        .execute(&self.pool)
+        .await?;
+        Ok(())
+    }
+
+    /// Park a permanently failed event (retry_count >= DLQ_MAX_RETRIES).
+    pub async fn park_permanently(&self, id: uuid::Uuid) -> Result<(), sqlx::Error> {
+        let far_future = Utc::now() + chrono::Duration::days(365);
+        sqlx::query("UPDATE failed_events SET retry_at = $1 WHERE id = $2")
+            .bind(far_future)
+            .bind(id)
+            .execute(&self.pool)
+            .await?;
+        Ok(())
+    }
+}

crates/adapters/postgres/src/feed.rs

@@ -0,0 +1,399 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use chrono::{DateTime, Utc};
+
+use domain::{
+    errors::DomainError,
+    models::{
+        feed::{FeedEntry, Paginated},
+        thought::{Thought, Visibility},
+        user::User,
+    },
+    ports::{FeedQuery, FeedRepository, FeedScope},
+    value_objects::{Content, Email, PasswordHash, ThoughtId, UserId, Username},
+};
+use sqlx::PgPool;
+
+pub struct PgFeedRepository {
+    pool: PgPool,
+}
+impl PgFeedRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[derive(sqlx::FromRow)]
+struct FeedRow {
+    thought_id: uuid::Uuid,
+    t_user_id: uuid::Uuid,
+    content: String,
+    in_reply_to_id: Option<uuid::Uuid>,
+    visibility: String,
+    content_warning: Option<String>,
+    sensitive: bool,
+    t_local: bool,
+    thought_created_at: DateTime<Utc>,
+    updated_at: Option<DateTime<Utc>>,
+    author_id: uuid::Uuid,
+    username: String,
+    email: String,
+    password_hash: String,
+    display_name: Option<String>,
+    bio: Option<String>,
+    avatar_url: Option<String>,
+    header_url: Option<String>,
+    custom_css: Option<String>,
+    author_local: bool,
+    author_created_at: DateTime<Utc>,
+    author_updated_at: DateTime<Utc>,
+    like_count: i64,
+    boost_count: i64,
+    reply_count: i64,
+    liked_by_viewer: bool,
+    boosted_by_viewer: bool,
+}
+
+fn federation_following_clause(follower: Option<uuid::Uuid>) -> String {
+    match follower {
+        Some(fid) => format!(
+            " OR t.user_id IN (
+                SELECT u2.id FROM users u2
+                JOIN federation_following ff ON u2.ap_id = ff.remote_actor_url
+                WHERE ff.local_user_id = '{fid}'
+            )"
+        ),
+        None => String::new(),
+    }
+}
+
+fn feed_select(viewer: Option<uuid::Uuid>) -> String {
+    let viewer_checks = match viewer {
+        Some(uid) => format!(
+            "EXISTS(SELECT 1 FROM likes WHERE user_id='{uid}' AND thought_id=t.id) AS liked_by_viewer,
+             EXISTS(SELECT 1 FROM boosts WHERE user_id='{uid}' AND thought_id=t.id) AS boosted_by_viewer"
+        ),
+        None => "false AS liked_by_viewer, false AS boosted_by_viewer".to_string(),
+    };
+    format!(
+        "
+    SELECT
+        t.id AS thought_id, t.user_id AS t_user_id, t.content,
+        t.in_reply_to_id,
+        t.visibility, t.content_warning, t.sensitive, t.local AS t_local,
+        t.created_at AS thought_created_at, t.updated_at,
+        u.id AS author_id,
+        CASE WHEN NOT u.local AND ra.handle IS NOT NULL AND ra.handle != ''
+             THEN '@' || ra.handle ||
+                  CASE WHEN ra.handle NOT LIKE '%@%'
+                       THEN '@' || SPLIT_PART(ra.url, '/', 3)
+                       ELSE '' END
+             ELSE u.username END AS username,
+        u.email, u.password_hash,
+        COALESCE(ra.display_name, u.display_name) AS display_name,
+        u.bio,
+        COALESCE(ra.avatar_url, u.avatar_url) AS avatar_url,
+        u.header_url, u.custom_css,
+        u.local AS author_local,
+        u.created_at AS author_created_at, u.updated_at AS author_updated_at,
+        (SELECT COUNT(*) FROM likes l WHERE l.thought_id=t.id) AS like_count,
+        (SELECT COUNT(*) FROM boosts b WHERE b.thought_id=t.id) AS boost_count,
+        (SELECT COUNT(*) FROM thoughts r WHERE r.in_reply_to_id=t.id) AS reply_count,
+        {viewer_checks}
+    FROM thoughts t
+    JOIN users u ON u.id=t.user_id
+    LEFT JOIN remote_actors ra ON u.ap_id = ra.url"
+    )
+}
+
+fn row_to_entry(r: FeedRow, viewer: Option<uuid::Uuid>) -> Result<FeedEntry, DomainError> {
+    let thought = Thought {
+        id: ThoughtId::from_uuid(r.thought_id),
+        user_id: UserId::from_uuid(r.t_user_id),
+        content: Content::new_remote(r.content),
+        in_reply_to_id: r.in_reply_to_id.map(ThoughtId::from_uuid),
+        visibility: Visibility::from_db_str(&r.visibility)?,
+        content_warning: r.content_warning,
+        sensitive: r.sensitive,
+        local: r.t_local,
+        created_at: r.thought_created_at,
+        updated_at: r.updated_at,
+    };
+    let author = User {
+        id: UserId::from_uuid(r.author_id),
+        username: Username::from_trusted(r.username),
+        email: Email::from_trusted(r.email),
+        password_hash: PasswordHash(r.password_hash),
+        display_name: r.display_name,
+        bio: r.bio,
+        avatar_url: r.avatar_url,
+        header_url: r.header_url,
+        custom_css: r.custom_css,
+        local: r.author_local,
+        created_at: r.author_created_at,
+        updated_at: r.author_updated_at,
+    };
+    Ok(FeedEntry {
+        thought,
+        author,
+        stats: domain::models::feed::EngagementStats {
+            like_count: r.like_count,
+            boost_count: r.boost_count,
+            reply_count: r.reply_count,
+        },
+        viewer: viewer.map(|_| domain::models::feed::ViewerContext {
+            liked: r.liked_by_viewer,
+            boosted: r.boosted_by_viewer,
+        }),
+    })
+}
+
+#[async_trait]
+impl FeedRepository for PgFeedRepository {
+    async fn query(&self, q: &FeedQuery) -> Result<Paginated<FeedEntry>, DomainError> {
+        let viewer = q.viewer_id.as_ref().map(|v| v.as_uuid());
+        let page = &q.page;
+
+        match &q.scope {
+            FeedScope::Home { following_ids } => {
+                let ids: Vec<uuid::Uuid> = following_ids.iter().map(|id| id.as_uuid()).collect();
+                let fed_clause = federation_following_clause(viewer);
+                let count_sql = format!(
+                    "SELECT COUNT(*) FROM thoughts t WHERE (t.user_id=ANY($1){}) AND t.visibility != 'direct'",
+                    fed_clause
+                );
+                let total: i64 = sqlx::query_scalar(&count_sql)
+                    .bind(&ids)
+                    .fetch_one(&self.pool)
+                    .await
+                    .into_domain()?;
+
+                let sel = feed_select(viewer);
+                let sql = format!("{sel} WHERE (t.user_id=ANY($1){}) AND t.visibility != 'direct' ORDER BY t.created_at DESC LIMIT $2 OFFSET $3", fed_clause);
+                let rows = sqlx::query_as::<_, FeedRow>(&sql)
+                    .bind(&ids)
+                    .bind(page.limit())
+                    .bind(page.offset())
+                    .fetch_all(&self.pool)
+                    .await
+                    .into_domain()?;
+
+                Ok(Paginated {
+                    items: rows
+                        .into_iter()
+                        .map(|r| row_to_entry(r, viewer))
+                        .collect::<Result<Vec<_>, _>>()?,
+                    total,
+                    page: page.page,
+                    per_page: page.per_page,
+                })
+            }
+
+            FeedScope::Public => {
+                let total: i64 = sqlx::query_scalar(
+                    "SELECT COUNT(*) FROM thoughts t WHERE t.local=true AND t.visibility='public'",
+                )
+                .fetch_one(&self.pool)
+                .await
+                .into_domain()?;
+
+                let sel = feed_select(viewer);
+                let sql = format!("{sel} WHERE t.local=true AND t.visibility='public' ORDER BY t.created_at DESC LIMIT $1 OFFSET $2");
+                let rows = sqlx::query_as::<_, FeedRow>(&sql)
+                    .bind(page.limit())
+                    .bind(page.offset())
+                    .fetch_all(&self.pool)
+                    .await
+                    .into_domain()?;
+
+                Ok(Paginated {
+                    items: rows
+                        .into_iter()
+                        .map(|r| row_to_entry(r, viewer))
+                        .collect::<Result<Vec<_>, _>>()?,
+                    total,
+                    page: page.page,
+                    per_page: page.per_page,
+                })
+            }
+
+            FeedScope::Search { query } => {
+                let total: i64 = sqlx::query_scalar(
+                    "SELECT COUNT(*) FROM thoughts t WHERE t.content % $1 AND t.visibility='public'",
+                )
+                .bind(query)
+                .fetch_one(&self.pool)
+                .await
+                .into_domain()?;
+
+                let sel = feed_select(viewer);
+                let sql = format!("{sel} WHERE t.content % $1 AND t.visibility='public' ORDER BY similarity(t.content, $1) DESC LIMIT $2 OFFSET $3");
+                let rows = sqlx::query_as::<_, FeedRow>(&sql)
+                    .bind(query)
+                    .bind(page.limit())
+                    .bind(page.offset())
+                    .fetch_all(&self.pool)
+                    .await
+                    .into_domain()?;
+
+                Ok(Paginated {
+                    items: rows
+                        .into_iter()
+                        .map(|r| row_to_entry(r, viewer))
+                        .collect::<Result<Vec<_>, _>>()?,
+                    total,
+                    page: page.page,
+                    per_page: page.per_page,
+                })
+            }
+
+            FeedScope::Tag { tag_name } => {
+                let total: i64 = sqlx::query_scalar(
+                    "SELECT COUNT(*) FROM thoughts t
+                     JOIN thought_tags tt ON tt.thought_id = t.id
+                     JOIN tags tg ON tg.id = tt.tag_id
+                     WHERE tg.name = $1 AND t.visibility = 'public'",
+                )
+                .bind(tag_name)
+                .fetch_one(&self.pool)
+                .await
+                .into_domain()?;
+
+                let sel = feed_select(viewer);
+                let sql = format!(
+                    "{sel}
+                     JOIN thought_tags tt ON tt.thought_id = t.id
+                     JOIN tags tg ON tg.id = tt.tag_id
+                     WHERE tg.name = $1 AND t.visibility = 'public'
+                     ORDER BY t.created_at DESC LIMIT $2 OFFSET $3"
+                );
+                let rows = sqlx::query_as::<_, FeedRow>(&sql)
+                    .bind(tag_name)
+                    .bind(page.limit())
+                    .bind(page.offset())
+                    .fetch_all(&self.pool)
+                    .await
+                    .into_domain()?;
+
+                Ok(Paginated {
+                    items: rows
+                        .into_iter()
+                        .map(|r| row_to_entry(r, viewer))
+                        .collect::<Result<Vec<_>, _>>()?,
+                    total,
+                    page: page.page,
+                    per_page: page.per_page,
+                })
+            }
+
+            FeedScope::User { user_id } => {
+                let uid = user_id.as_uuid();
+                // Use nil UUID for unauthenticated viewers — won't match owner or follower checks.
+                let viewer_uuid = viewer.unwrap_or(uuid::Uuid::nil());
+
+                let total: i64 = sqlx::query_scalar(
+                    "SELECT COUNT(*) FROM thoughts t WHERE t.user_id = $1 AND ($2::uuid = $1 OR (t.visibility != 'direct' AND (t.visibility IN ('public', 'unlisted') OR (t.visibility = 'followers' AND EXISTS(SELECT 1 FROM follows WHERE follower_id = $2 AND following_id = $1 AND state = 'accepted')))))",
+                )
+                .bind(uid)
+                .bind(viewer_uuid)
+                .fetch_one(&self.pool)
+                .await
+                .into_domain()?;
+
+                let sel = feed_select(viewer);
+                let sql = format!("{sel} WHERE t.user_id = $1 AND ($4::uuid = $1 OR (t.visibility != 'direct' AND (t.visibility IN ('public', 'unlisted') OR (t.visibility = 'followers' AND EXISTS(SELECT 1 FROM follows WHERE follower_id = $4 AND following_id = $1 AND state = 'accepted'))))) ORDER BY t.created_at DESC LIMIT $2 OFFSET $3");
+                let rows = sqlx::query_as::<_, FeedRow>(&sql)
+                    .bind(uid)
+                    .bind(page.limit())
+                    .bind(page.offset())
+                    .bind(viewer_uuid)
+                    .fetch_all(&self.pool)
+                    .await
+                    .into_domain()?;
+
+                Ok(Paginated {
+                    items: rows
+                        .into_iter()
+                        .map(|r| row_to_entry(r, viewer))
+                        .collect::<Result<Vec<_>, _>>()?,
+                    total,
+                    page: page.page,
+                    per_page: page.per_page,
+                })
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{thought::PgThoughtRepository, user::PgUserRepository};
+    use domain::{
+        models::{
+            feed::PageParams,
+            thought::{Thought, Visibility},
+            user::User,
+        },
+        ports::{FeedQuery, ThoughtRepository, UserWriter},
+        value_objects::*,
+    };
+
+    async fn seed(pool: &sqlx::PgPool, username: &str, content: &str) -> (User, Thought) {
+        let urepo = PgUserRepository::new(pool.clone());
+        let trepo = PgThoughtRepository::new(pool.clone());
+        let u = User::new_local(
+            UserId::new(),
+            Username::new(username).unwrap(),
+            Email::new(format!("{username}@ex.com")).unwrap(),
+            PasswordHash("h".into()),
+        );
+        urepo.save(&u).await.unwrap();
+        let t = Thought::new_local(
+            ThoughtId::new(),
+            u.id.clone(),
+            Content::new_local(content).unwrap(),
+            None,
+            Visibility::Public,
+            None,
+            false,
+        );
+        trepo.save(&t).await.unwrap();
+        (u, t)
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn public_feed_returns_local_thoughts(pool: sqlx::PgPool) {
+        let (_, _) = seed(&pool, "alice", "hello").await;
+        let repo = PgFeedRepository::new(pool);
+        let result = repo
+            .query(&FeedQuery::public(
+                PageParams { page: 1, per_page: 20 },
+                None,
+            ))
+            .await
+            .unwrap();
+        assert_eq!(result.total, 1);
+        assert_eq!(result.items[0].thought.content.as_str(), "hello");
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn search_returns_matching_thoughts(pool: sqlx::PgPool) {
+        let (_, _) = seed(&pool, "alice", "hello world").await;
+        let (_, _) = seed(&pool, "bob", "goodbye world").await;
+        let repo = PgFeedRepository::new(pool);
+        let result = repo
+            .query(&FeedQuery::search(
+                "hello world",
+                PageParams { page: 1, per_page: 20 },
+                None,
+            ))
+            .await
+            .unwrap();
+        assert!(result.total >= 1);
+        assert!(result
+            .items
+            .iter()
+            .any(|e| e.thought.content.as_str() == "hello world"));
+    }
+}

crates/adapters/postgres/src/follow.rs

@@ -0,0 +1,252 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use chrono::{DateTime, Utc};
+
+use domain::{
+    errors::DomainError,
+    models::{
+        feed::{PageParams, Paginated},
+        social::{Follow, FollowState},
+        user::User,
+    },
+    ports::FollowRepository,
+    value_objects::UserId,
+};
+use sqlx::PgPool;
+
+pub struct PgFollowRepository {
+    pool: PgPool,
+}
+impl PgFollowRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl FollowRepository for PgFollowRepository {
+    async fn save(&self, f: &Follow) -> Result<(), DomainError> {
+        sqlx::query(
+            "INSERT INTO follows(follower_id,following_id,state,ap_id,created_at)
+             VALUES($1,$2,$3,$4,$5)
+             ON CONFLICT(follower_id,following_id) DO UPDATE SET state=EXCLUDED.state,ap_id=EXCLUDED.ap_id"
+        )
+        .bind(f.follower_id.as_uuid())
+        .bind(f.following_id.as_uuid())
+        .bind(f.state.as_str())
+        .bind(&f.ap_id)
+        .bind(f.created_at)
+        .execute(&self.pool)
+        .await
+        .into_domain()
+        .map(|_| ())
+    }
+
+    async fn delete(&self, follower_id: &UserId, following_id: &UserId) -> Result<(), DomainError> {
+        let r = sqlx::query("DELETE FROM follows WHERE follower_id=$1 AND following_id=$2")
+            .bind(follower_id.as_uuid())
+            .bind(following_id.as_uuid())
+            .execute(&self.pool)
+            .await
+            .into_domain()?;
+        if r.rows_affected() == 0 {
+            return Err(DomainError::NotFound);
+        }
+        Ok(())
+    }
+
+    async fn find(
+        &self,
+        follower_id: &UserId,
+        following_id: &UserId,
+    ) -> Result<Option<Follow>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            follower_id: uuid::Uuid,
+            following_id: uuid::Uuid,
+            state: String,
+            ap_id: Option<String>,
+            created_at: DateTime<Utc>,
+        }
+        sqlx::query_as::<_, Row>(
+            "SELECT follower_id,following_id,state,ap_id,created_at FROM follows WHERE follower_id=$1 AND following_id=$2"
+        )
+        .bind(follower_id.as_uuid())
+        .bind(following_id.as_uuid())
+        .fetch_optional(&self.pool)
+        .await
+        .into_domain()
+        .and_then(|o| {
+            o.map(|r| {
+                Ok(Follow {
+                    follower_id: UserId::from_uuid(r.follower_id),
+                    following_id: UserId::from_uuid(r.following_id),
+                    state: FollowState::from_db_str(&r.state)?,
+                    ap_id: r.ap_id,
+                    created_at: r.created_at,
+                })
+            })
+            .transpose()
+        })
+    }
+
+    async fn update_state(
+        &self,
+        follower_id: &UserId,
+        following_id: &UserId,
+        state: &FollowState,
+    ) -> Result<(), DomainError> {
+        sqlx::query("UPDATE follows SET state=$3 WHERE follower_id=$1 AND following_id=$2")
+            .bind(follower_id.as_uuid())
+            .bind(following_id.as_uuid())
+            .bind(state.as_str())
+            .execute(&self.pool)
+            .await
+            .into_domain()
+            .map(|_| ())
+    }
+
+    async fn list_followers(
+        &self,
+        user_id: &UserId,
+        page: &PageParams,
+    ) -> Result<Paginated<User>, DomainError> {
+        let total: i64 = sqlx::query_scalar(
+            "SELECT COUNT(*) FROM follows WHERE following_id=$1 AND state='accepted'",
+        )
+        .bind(user_id.as_uuid())
+        .fetch_one(&self.pool)
+        .await
+        .into_domain()?;
+
+        let rows = sqlx::query_as::<_, crate::user::UserRow>(
+            "SELECT u.id,u.username,u.email,u.password_hash,u.display_name,u.bio,u.avatar_url,u.header_url,u.custom_css,u.local,u.ap_id,u.inbox_url,u.created_at,u.updated_at
+             FROM users u JOIN follows f ON f.follower_id=u.id
+             WHERE f.following_id=$1 AND f.state='accepted'
+             ORDER BY f.created_at DESC LIMIT $2 OFFSET $3"
+        )
+        .bind(user_id.as_uuid())
+        .bind(page.limit())
+        .bind(page.offset())
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()?;
+
+        Ok(Paginated {
+            items: rows.into_iter().map(User::from).collect(),
+            total,
+            page: page.page,
+            per_page: page.per_page,
+        })
+    }
+
+    async fn list_following(
+        &self,
+        user_id: &UserId,
+        page: &PageParams,
+    ) -> Result<Paginated<User>, DomainError> {
+        let total: i64 = sqlx::query_scalar(
+            "SELECT COUNT(*) FROM follows WHERE follower_id=$1 AND state='accepted'",
+        )
+        .bind(user_id.as_uuid())
+        .fetch_one(&self.pool)
+        .await
+        .into_domain()?;
+
+        let rows = sqlx::query_as::<_, crate::user::UserRow>(
+            "SELECT u.id,u.username,u.email,u.password_hash,u.display_name,u.bio,u.avatar_url,u.header_url,u.custom_css,u.local,u.ap_id,u.inbox_url,u.created_at,u.updated_at
+             FROM users u JOIN follows f ON f.following_id=u.id
+             WHERE f.follower_id=$1 AND f.state='accepted'
+             ORDER BY f.created_at DESC LIMIT $2 OFFSET $3"
+        )
+        .bind(user_id.as_uuid())
+        .bind(page.limit())
+        .bind(page.offset())
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()?;
+
+        Ok(Paginated {
+            items: rows.into_iter().map(User::from).collect(),
+            total,
+            page: page.page,
+            per_page: page.per_page,
+        })
+    }
+
+    async fn get_accepted_following_ids(
+        &self,
+        user_id: &UserId,
+    ) -> Result<Vec<UserId>, DomainError> {
+        let ids: Vec<uuid::Uuid> = sqlx::query_scalar(
+            "SELECT following_id FROM follows WHERE follower_id=$1 AND state='accepted'",
+        )
+        .bind(user_id.as_uuid())
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()?;
+        Ok(ids.into_iter().map(UserId::from_uuid).collect())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_helpers::seed_user;
+    use chrono::Utc;
+    use domain::value_objects::*;
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn save_and_find_follow(pool: sqlx::PgPool) {
+        let alice = seed_user(&pool, "alice", "alice@ex.com").await;
+        let bob = seed_user(&pool, "bob", "bob@ex.com").await;
+        let repo = PgFollowRepository::new(pool);
+        let follow = Follow {
+            follower_id: alice.id.clone(),
+            following_id: bob.id.clone(),
+            state: FollowState::Accepted,
+            ap_id: None,
+            created_at: Utc::now(),
+        };
+        repo.save(&follow).await.unwrap();
+        let found = repo.find(&alice.id, &bob.id).await.unwrap().unwrap();
+        assert_eq!(found.state, FollowState::Accepted);
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn update_state(pool: sqlx::PgPool) {
+        let alice = seed_user(&pool, "alice", "alice@ex.com").await;
+        let bob = seed_user(&pool, "bob", "bob@ex.com").await;
+        let repo = PgFollowRepository::new(pool);
+        let follow = Follow {
+            follower_id: alice.id.clone(),
+            following_id: bob.id.clone(),
+            state: FollowState::Pending,
+            ap_id: None,
+            created_at: Utc::now(),
+        };
+        repo.save(&follow).await.unwrap();
+        repo.update_state(&alice.id, &bob.id, &FollowState::Accepted)
+            .await
+            .unwrap();
+        let found = repo.find(&alice.id, &bob.id).await.unwrap().unwrap();
+        assert_eq!(found.state, FollowState::Accepted);
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn get_accepted_following_ids(pool: sqlx::PgPool) {
+        let alice = seed_user(&pool, "alice", "alice@ex.com").await;
+        let bob = seed_user(&pool, "bob", "bob@ex.com").await;
+        let repo = PgFollowRepository::new(pool);
+        let follow = Follow {
+            follower_id: alice.id.clone(),
+            following_id: bob.id.clone(),
+            state: FollowState::Accepted,
+            ap_id: None,
+            created_at: Utc::now(),
+        };
+        repo.save(&follow).await.unwrap();
+        let ids = repo.get_accepted_following_ids(&alice.id).await.unwrap();
+        assert_eq!(ids, vec![bob.id]);
+    }
+}

crates/adapters/postgres/src/lib.rs

@@ -0,0 +1,20 @@
+pub mod activitypub;
+pub mod engagement;
+pub mod api_key;
+pub mod block;
+pub mod boost;
+mod db_error;
+pub mod failed_event;
+pub mod outbox;
+pub mod feed;
+pub mod follow;
+pub mod like;
+pub mod notification;
+pub mod remote_actor;
+pub mod remote_actor_connections;
+pub mod tag;
+#[cfg(test)]
+pub(crate) mod test_helpers;
+pub mod thought;
+pub mod top_friend;
+pub mod user;

crates/adapters/postgres/src/like.rs

@@ -0,0 +1,110 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use chrono::{DateTime, Utc};
+use domain::{
+    errors::DomainError,
+    models::social::Like,
+    ports::LikeRepository,
+    value_objects::{LikeId, ThoughtId, UserId},
+};
+use sqlx::PgPool;
+
+pub struct PgLikeRepository {
+    pool: PgPool,
+}
+impl PgLikeRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl LikeRepository for PgLikeRepository {
+    async fn save(&self, l: &Like) -> Result<(), DomainError> {
+        sqlx::query(
+            "INSERT INTO likes(id,user_id,thought_id,ap_id,created_at) VALUES($1,$2,$3,$4,$5) ON CONFLICT(user_id,thought_id) DO NOTHING"
+        )
+        .bind(l.id.as_uuid()).bind(l.user_id.as_uuid()).bind(l.thought_id.as_uuid()).bind(&l.ap_id).bind(l.created_at)
+        .execute(&self.pool).await.into_domain().map(|_| ())
+    }
+
+    async fn delete(&self, user_id: &UserId, thought_id: &ThoughtId) -> Result<(), DomainError> {
+        let r = sqlx::query("DELETE FROM likes WHERE user_id=$1 AND thought_id=$2")
+            .bind(user_id.as_uuid())
+            .bind(thought_id.as_uuid())
+            .execute(&self.pool)
+            .await
+            .into_domain()?;
+        if r.rows_affected() == 0 {
+            return Err(DomainError::NotFound);
+        }
+        Ok(())
+    }
+
+    async fn find(
+        &self,
+        user_id: &UserId,
+        thought_id: &ThoughtId,
+    ) -> Result<Option<Like>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            id: uuid::Uuid,
+            user_id: uuid::Uuid,
+            thought_id: uuid::Uuid,
+            ap_id: Option<String>,
+            created_at: DateTime<Utc>,
+        }
+        sqlx::query_as::<_, Row>("SELECT id,user_id,thought_id,ap_id,created_at FROM likes WHERE user_id=$1 AND thought_id=$2")
+            .bind(user_id.as_uuid()).bind(thought_id.as_uuid())
+            .fetch_optional(&self.pool).await
+            .into_domain()
+            .map(|o| o.map(|r| Like { id: LikeId::from_uuid(r.id), user_id: UserId::from_uuid(r.user_id), thought_id: ThoughtId::from_uuid(r.thought_id), ap_id: r.ap_id, created_at: r.created_at }))
+    }
+
+    async fn count_for_thought(&self, thought_id: &ThoughtId) -> Result<i64, DomainError> {
+        sqlx::query_scalar("SELECT COUNT(*) FROM likes WHERE thought_id=$1")
+            .bind(thought_id.as_uuid())
+            .fetch_one(&self.pool)
+            .await
+            .into_domain()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_helpers::seed_user_and_thought;
+    use chrono::Utc;
+    use domain::value_objects::*;
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn like_and_count(pool: sqlx::PgPool) {
+        let (user, thought) = seed_user_and_thought(&pool).await;
+        let repo = PgLikeRepository::new(pool);
+        let like = Like {
+            id: LikeId::new(),
+            user_id: user.id.clone(),
+            thought_id: thought.id.clone(),
+            ap_id: None,
+            created_at: Utc::now(),
+        };
+        repo.save(&like).await.unwrap();
+        assert_eq!(repo.count_for_thought(&thought.id).await.unwrap(), 1);
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn unlike(pool: sqlx::PgPool) {
+        let (user, thought) = seed_user_and_thought(&pool).await;
+        let repo = PgLikeRepository::new(pool);
+        let like = Like {
+            id: LikeId::new(),
+            user_id: user.id.clone(),
+            thought_id: thought.id.clone(),
+            ap_id: None,
+            created_at: Utc::now(),
+        };
+        repo.save(&like).await.unwrap();
+        repo.delete(&user.id, &thought.id).await.unwrap();
+        assert_eq!(repo.count_for_thought(&thought.id).await.unwrap(), 0);
+    }
+}

crates/adapters/postgres/src/notification.rs

@@ -0,0 +1,230 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use chrono::{DateTime, Utc};
+
+use domain::{
+    errors::DomainError,
+    models::{
+        feed::{PageParams, Paginated},
+        notification::{Notification, NotificationKind},
+    },
+    ports::NotificationRepository,
+    value_objects::{NotificationId, ThoughtId, UserId},
+};
+use sqlx::PgPool;
+
+pub struct PgNotificationRepository {
+    pool: PgPool,
+}
+impl PgNotificationRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[derive(sqlx::FromRow)]
+struct NotificationRow {
+    id: uuid::Uuid,
+    user_id: uuid::Uuid,
+    notification_type: String,
+    from_user_id: Option<uuid::Uuid>,
+    thought_id: Option<uuid::Uuid>,
+    read: bool,
+    created_at: DateTime<Utc>,
+}
+
+fn row_to_notification(r: NotificationRow) -> Result<Notification, DomainError> {
+    let from_user_id = r
+        .from_user_id
+        .map(UserId::from_uuid)
+        .ok_or_else(|| DomainError::Internal("notification missing from_user_id".into()))?;
+
+    let kind = match r.notification_type.as_str() {
+        "follow" => NotificationKind::Follow { from_user_id },
+        other => {
+            let thought_id = r.thought_id.map(ThoughtId::from_uuid).ok_or_else(|| {
+                DomainError::Internal(format!("notification type '{other}' missing thought_id"))
+            })?;
+            match other {
+                "like" => NotificationKind::Like {
+                    thought_id,
+                    from_user_id,
+                },
+                "boost" => NotificationKind::Boost {
+                    thought_id,
+                    from_user_id,
+                },
+                "reply" => NotificationKind::Reply {
+                    thought_id,
+                    from_user_id,
+                },
+                "mention" => NotificationKind::Mention {
+                    thought_id,
+                    from_user_id,
+                },
+                _ => {
+                    return Err(DomainError::Internal(format!(
+                        "unknown notification type: {other}"
+                    )))
+                }
+            }
+        }
+    };
+
+    Ok(Notification {
+        id: NotificationId::from_uuid(r.id),
+        user_id: UserId::from_uuid(r.user_id),
+        kind,
+        read: r.read,
+        created_at: r.created_at,
+    })
+}
+
+#[async_trait]
+impl NotificationRepository for PgNotificationRepository {
+    async fn save(&self, n: &Notification) -> Result<(), DomainError> {
+        sqlx::query(
+            "INSERT INTO notifications(id,user_id,notification_type,from_user_id,thought_id,read,created_at)
+             VALUES($1,$2,$3,$4,$5,$6,$7)
+             ON CONFLICT(id) DO NOTHING"
+        )
+        .bind(n.id.as_uuid())
+        .bind(n.user_id.as_uuid())
+        .bind(n.kind.kind_str())
+        .bind(n.kind.from_user_id().as_uuid())
+        .bind(n.kind.thought_id().map(|t| t.as_uuid()))
+        .bind(n.read)
+        .bind(n.created_at)
+        .execute(&self.pool)
+        .await
+        .into_domain()
+        .map(|_| ())
+    }
+
+    async fn list_for_user(
+        &self,
+        user_id: &UserId,
+        page: &PageParams,
+    ) -> Result<Paginated<Notification>, DomainError> {
+        let total: i64 = sqlx::query_scalar("SELECT COUNT(*) FROM notifications WHERE user_id=$1")
+            .bind(user_id.as_uuid())
+            .fetch_one(&self.pool)
+            .await
+            .into_domain()?;
+        let rows = sqlx::query_as::<_, NotificationRow>(
+            "SELECT id,user_id,notification_type,from_user_id,thought_id,read,created_at FROM notifications WHERE user_id=$1 ORDER BY created_at DESC LIMIT $2 OFFSET $3"
+        ).bind(user_id.as_uuid()).bind(page.limit()).bind(page.offset())
+        .fetch_all(&self.pool).await.into_domain()?;
+        let items = rows
+            .into_iter()
+            .map(row_to_notification)
+            .collect::<Result<Vec<_>, _>>()?;
+        Ok(Paginated {
+            items,
+            total,
+            page: page.page,
+            per_page: page.per_page,
+        })
+    }
+
+    async fn count_unread(&self, user_id: &UserId) -> Result<u64, DomainError> {
+        let count: i64 = sqlx::query_scalar(
+            "SELECT COUNT(*) FROM notifications WHERE user_id=$1 AND read=false",
+        )
+        .bind(user_id.as_uuid())
+        .fetch_one(&self.pool)
+        .await
+        .into_domain()?;
+        Ok(count as u64)
+    }
+
+    async fn mark_read(&self, id: &NotificationId, user_id: &UserId) -> Result<(), DomainError> {
+        sqlx::query("UPDATE notifications SET read=true WHERE id=$1 AND user_id=$2")
+            .bind(id.as_uuid())
+            .bind(user_id.as_uuid())
+            .execute(&self.pool)
+            .await
+            .into_domain()
+            .map(|_| ())
+    }
+
+    async fn mark_all_read(&self, user_id: &UserId) -> Result<(), DomainError> {
+        sqlx::query("UPDATE notifications SET read=true WHERE user_id=$1")
+            .bind(user_id.as_uuid())
+            .execute(&self.pool)
+            .await
+            .into_domain()
+            .map(|_| ())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_helpers;
+    use chrono::Utc;
+    use domain::{
+        models::{notification::NotificationKind, user::User},
+        value_objects::*,
+    };
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn save_and_list(pool: sqlx::PgPool) {
+        let user = test_helpers::seed_user(&pool, "alice", "alice@ex.com").await;
+        let from_user = test_helpers::seed_user(&pool, "bob", "bob@ex.com").await;
+        let repo = PgNotificationRepository::new(pool);
+        use domain::models::feed::PageParams;
+        let n = Notification {
+            id: NotificationId::new(),
+            user_id: user.id.clone(),
+            kind: NotificationKind::Follow {
+                from_user_id: from_user.id.clone(),
+            },
+            read: false,
+            created_at: Utc::now(),
+        };
+        repo.save(&n).await.unwrap();
+        let page = repo
+            .list_for_user(
+                &user.id,
+                &PageParams {
+                    page: 1,
+                    per_page: 20,
+                },
+            )
+            .await
+            .unwrap();
+        assert_eq!(page.total, 1);
+        assert!(!page.items[0].read);
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn mark_all_read(pool: sqlx::PgPool) {
+        let user = test_helpers::seed_user(&pool, "alice", "alice@ex.com").await;
+        let from_user = test_helpers::seed_user(&pool, "bob", "bob@ex.com").await;
+        let repo = PgNotificationRepository::new(pool);
+        use domain::models::feed::PageParams;
+        let n = Notification {
+            id: NotificationId::new(),
+            user_id: user.id.clone(),
+            kind: NotificationKind::Follow {
+                from_user_id: from_user.id.clone(),
+            },
+            read: false,
+            created_at: Utc::now(),
+        };
+        repo.save(&n).await.unwrap();
+        repo.mark_all_read(&user.id).await.unwrap();
+        let page = repo
+            .list_for_user(
+                &user.id,
+                &PageParams {
+                    page: 1,
+                    per_page: 20,
+                },
+            )
+            .await
+            .unwrap();
+        assert!(page.items[0].read);
+    }
+}

crates/adapters/postgres/src/outbox.rs

@@ -0,0 +1,61 @@
+use async_trait::async_trait;
+use domain::{errors::DomainError, events::DomainEvent, ports::OutboxWriter};
+use event_payload::EventPayload;
+use sqlx::PgPool;
+use uuid::Uuid;
+
+pub struct PgOutboxWriter {
+    pool: PgPool,
+}
+
+impl PgOutboxWriter {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+/// Primary aggregate UUID for an event — used to populate `aggregate_id`.
+fn aggregate_id(event: &DomainEvent) -> Uuid {
+    match event {
+        DomainEvent::ThoughtCreated { thought_id, .. } => thought_id.as_uuid(),
+        DomainEvent::ThoughtDeleted { thought_id, .. } => thought_id.as_uuid(),
+        DomainEvent::ThoughtUpdated { thought_id, .. } => thought_id.as_uuid(),
+        DomainEvent::LikeAdded { thought_id, .. } => thought_id.as_uuid(),
+        DomainEvent::LikeRemoved { thought_id, .. } => thought_id.as_uuid(),
+        DomainEvent::BoostAdded { thought_id, .. } => thought_id.as_uuid(),
+        DomainEvent::BoostRemoved { thought_id, .. } => thought_id.as_uuid(),
+        DomainEvent::FollowRequested { follower_id, .. } => follower_id.as_uuid(),
+        DomainEvent::FollowAccepted { follower_id, .. } => follower_id.as_uuid(),
+        DomainEvent::FollowRejected { follower_id, .. } => follower_id.as_uuid(),
+        DomainEvent::Unfollowed { follower_id, .. } => follower_id.as_uuid(),
+        DomainEvent::UserBlocked { blocker_id, .. } => blocker_id.as_uuid(),
+        DomainEvent::UserUnblocked { blocker_id, .. } => blocker_id.as_uuid(),
+        DomainEvent::UserRegistered { user_id } => user_id.as_uuid(),
+        DomainEvent::ProfileUpdated { user_id } => user_id.as_uuid(),
+        DomainEvent::MentionReceived { thought_id, .. } => thought_id.as_uuid(),
+    }
+}
+
+#[async_trait]
+impl OutboxWriter for PgOutboxWriter {
+    async fn append(&self, event: &DomainEvent) -> Result<(), DomainError> {
+        let payload = EventPayload::from(event);
+        let event_type = payload.subject();
+        let payload_json =
+            serde_json::to_value(&payload).map_err(|e| DomainError::Internal(e.to_string()))?;
+        let agg_id = aggregate_id(event);
+
+        sqlx::query(
+            "INSERT INTO outbox_events (aggregate_id, event_type, payload) \
+             VALUES ($1, $2, $3)",
+        )
+        .bind(agg_id)
+        .bind(event_type)
+        .bind(payload_json)
+        .execute(&self.pool)
+        .await
+        .map_err(|e| DomainError::Internal(e.to_string()))?;
+
+        Ok(())
+    }
+}

crates/adapters/postgres/src/remote_actor.rs

@@ -0,0 +1,59 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use chrono::{DateTime, Utc};
+use domain::{
+    errors::DomainError, models::remote_actor::RemoteActor, ports::RemoteActorRepository,
+};
+use sqlx::PgPool;
+
+pub struct PgRemoteActorRepository {
+    pool: PgPool,
+}
+impl PgRemoteActorRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl RemoteActorRepository for PgRemoteActorRepository {
+    async fn upsert(&self, a: &RemoteActor) -> Result<(), DomainError> {
+        sqlx::query(
+            "INSERT INTO remote_actors(url,handle,display_name,avatar_url,last_fetched_at)
+             VALUES($1,$2,$3,$4,$5)
+             ON CONFLICT(url) DO UPDATE SET handle=EXCLUDED.handle,display_name=EXCLUDED.display_name,
+             avatar_url=EXCLUDED.avatar_url,last_fetched_at=EXCLUDED.last_fetched_at"
+        )
+        .bind(&a.url).bind(&a.handle).bind(&a.display_name).bind(&a.avatar_url).bind(a.last_fetched_at)
+        .execute(&self.pool).await.into_domain().map(|_| ())
+    }
+
+    async fn find_by_url(&self, url: &str) -> Result<Option<RemoteActor>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            url: String,
+            handle: String,
+            display_name: Option<String>,
+            avatar_url: Option<String>,
+            last_fetched_at: DateTime<Utc>,
+        }
+        sqlx::query_as::<_, Row>(
+            "SELECT url,handle,display_name,avatar_url,last_fetched_at FROM remote_actors WHERE url=$1"
+        ).bind(url).fetch_optional(&self.pool).await
+        .into_domain()
+        .map(|o| o.map(|r| RemoteActor {
+            url: r.url,
+            handle: r.handle,
+            display_name: r.display_name,
+            avatar_url: r.avatar_url,
+            last_fetched_at: r.last_fetched_at,
+            bio: None,
+            banner_url: None,
+            also_known_as: None,
+            outbox_url: None,
+            followers_url: None,
+            following_url: None,
+            attachment: vec![],
+        }))
+    }
+}

crates/adapters/postgres/src/remote_actor_connections.rs

@@ -0,0 +1,111 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use domain::{
+    errors::DomainError, models::actor_connection_summary::ActorConnectionSummary,
+    ports::RemoteActorConnectionRepository,
+};
+use sqlx::PgPool;
+
+pub struct PgRemoteActorConnectionRepository {
+    pool: PgPool,
+}
+
+impl PgRemoteActorConnectionRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl RemoteActorConnectionRepository for PgRemoteActorConnectionRepository {
+    async fn upsert_connections(
+        &self,
+        actor_url: &str,
+        connection_type: &str,
+        page: u32,
+        actors: &[ActorConnectionSummary],
+    ) -> Result<(), DomainError> {
+        for actor in actors {
+            sqlx::query(
+                "INSERT INTO remote_actor_connections
+                    (actor_url, connection_type, page, connected_actor_url,
+                     connected_handle, connected_display_name, connected_avatar_url, fetched_at)
+                 VALUES ($1, $2, $3, $4, $5, $6, $7, NOW())
+                 ON CONFLICT(actor_url, connection_type, page, connected_actor_url)
+                 DO UPDATE SET
+                     connected_handle       = EXCLUDED.connected_handle,
+                     connected_display_name = EXCLUDED.connected_display_name,
+                     connected_avatar_url   = EXCLUDED.connected_avatar_url,
+                     fetched_at             = NOW()",
+            )
+            .bind(actor_url)
+            .bind(connection_type)
+            .bind(page as i32)
+            .bind(&actor.url)
+            .bind(&actor.handle)
+            .bind(&actor.display_name)
+            .bind(&actor.avatar_url)
+            .execute(&self.pool)
+            .await
+            .into_domain()?;
+        }
+        Ok(())
+    }
+
+    async fn list_connections(
+        &self,
+        actor_url: &str,
+        connection_type: &str,
+        page: u32,
+    ) -> Result<Vec<ActorConnectionSummary>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            connected_actor_url: String,
+            connected_handle: String,
+            connected_display_name: Option<String>,
+            connected_avatar_url: Option<String>,
+        }
+        let rows = sqlx::query_as::<_, Row>(
+            "SELECT connected_actor_url, connected_handle, connected_display_name, connected_avatar_url
+             FROM remote_actor_connections
+             WHERE actor_url = $1 AND connection_type = $2 AND page = $3
+             ORDER BY connected_handle",
+        )
+        .bind(actor_url)
+        .bind(connection_type)
+        .bind(page as i32)
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()?;
+
+        Ok(rows
+            .into_iter()
+            .map(|r| ActorConnectionSummary {
+                url: r.connected_actor_url,
+                handle: r.connected_handle,
+                display_name: r.connected_display_name,
+                avatar_url: r.connected_avatar_url,
+            })
+            .collect())
+    }
+
+    async fn connection_page_age(
+        &self,
+        actor_url: &str,
+        connection_type: &str,
+        page: u32,
+    ) -> Result<Option<chrono::DateTime<chrono::Utc>>, DomainError> {
+        let row: Option<(Option<chrono::DateTime<chrono::Utc>>,)> = sqlx::query_as(
+            "SELECT MAX(fetched_at) FROM remote_actor_connections
+             WHERE actor_url = $1 AND connection_type = $2 AND page = $3",
+        )
+        .bind(actor_url)
+        .bind(connection_type)
+        .bind(page as i32)
+        .fetch_optional(&self.pool)
+        .await
+        .into_domain()?;
+
+        Ok(row.and_then(|(ts,)| ts))
+    }
+}

crates/adapters/postgres/src/tag.rs

@@ -0,0 +1,184 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use domain::{
+    errors::DomainError,
+    models::{
+        feed::{PageParams, Paginated},
+        tag::Tag,
+        thought::Thought,
+    },
+    ports::TagRepository,
+    value_objects::ThoughtId,
+};
+use sqlx::PgPool;
+
+pub struct PgTagRepository {
+    pool: PgPool,
+}
+impl PgTagRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl TagRepository for PgTagRepository {
+    async fn find_or_create(&self, name: &str) -> Result<Tag, DomainError> {
+        let name = name.to_lowercase();
+        sqlx::query("INSERT INTO tags(name) VALUES($1) ON CONFLICT(name) DO NOTHING")
+            .bind(&name)
+            .execute(&self.pool)
+            .await
+            .into_domain()?;
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            id: i32,
+            name: String,
+        }
+        let row = sqlx::query_as::<_, Row>("SELECT id,name FROM tags WHERE name=$1")
+            .bind(&name)
+            .fetch_one(&self.pool)
+            .await
+            .into_domain()?;
+        Ok(Tag {
+            id: row.id,
+            name: row.name,
+        })
+    }
+
+    async fn attach_to_thought(
+        &self,
+        thought_id: &ThoughtId,
+        tag_id: i32,
+    ) -> Result<(), DomainError> {
+        sqlx::query(
+            "INSERT INTO thought_tags(thought_id,tag_id) VALUES($1,$2) ON CONFLICT DO NOTHING",
+        )
+        .bind(thought_id.as_uuid())
+        .bind(tag_id)
+        .execute(&self.pool)
+        .await
+        .into_domain()
+        .map(|_| ())
+    }
+
+    async fn detach_from_thought(&self, thought_id: &ThoughtId) -> Result<(), DomainError> {
+        sqlx::query("DELETE FROM thought_tags WHERE thought_id=$1")
+            .bind(thought_id.as_uuid())
+            .execute(&self.pool)
+            .await
+            .into_domain()
+            .map(|_| ())
+    }
+
+    async fn list_for_thought(&self, thought_id: &ThoughtId) -> Result<Vec<Tag>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            id: i32,
+            name: String,
+        }
+        sqlx::query_as::<_, Row>(
+            "SELECT t.id,t.name FROM tags t JOIN thought_tags tt ON tt.tag_id=t.id WHERE tt.thought_id=$1"
+        ).bind(thought_id.as_uuid()).fetch_all(&self.pool).await
+        .into_domain()
+        .map(|rows| rows.into_iter().map(|r| Tag { id: r.id, name: r.name }).collect())
+    }
+
+    async fn list_thoughts_by_tag(
+        &self,
+        tag_name: &str,
+        page: &PageParams,
+    ) -> Result<Paginated<Thought>, DomainError> {
+        let total: i64 = sqlx::query_scalar(
+            "SELECT COUNT(*) FROM thought_tags tt JOIN tags t ON t.id=tt.tag_id WHERE t.name=$1",
+        )
+        .bind(tag_name)
+        .fetch_one(&self.pool)
+        .await
+        .into_domain()?;
+
+        let rows = sqlx::query_as::<_, crate::thought::ThoughtRow>(
+            "SELECT th.id,th.user_id,th.content,th.in_reply_to_id,th.in_reply_to_url,th.ap_id,th.visibility,th.content_warning,th.sensitive,th.local,th.created_at,th.updated_at
+             FROM thoughts th JOIN thought_tags tt ON tt.thought_id=th.id JOIN tags t ON t.id=tt.tag_id
+             WHERE t.name=$1 ORDER BY th.created_at DESC LIMIT $2 OFFSET $3"
+        ).bind(tag_name).bind(page.limit()).bind(page.offset())
+        .fetch_all(&self.pool).await.into_domain()?;
+
+        Ok(Paginated {
+            items: rows
+                .into_iter()
+                .map(Thought::try_from)
+                .collect::<Result<Vec<_>, _>>()?,
+            total,
+            page: page.page,
+            per_page: page.per_page,
+        })
+    }
+
+    async fn popular_tags(&self, limit: usize) -> Result<Vec<(String, i64)>, DomainError> {
+        sqlx::query_as::<_, (String, i64)>(
+            "SELECT t.name, COUNT(tt.thought_id) AS thought_count
+             FROM tags t
+             JOIN thought_tags tt ON t.id = tt.tag_id
+             GROUP BY t.id, t.name
+             ORDER BY thought_count DESC
+             LIMIT $1",
+        )
+        .bind(limit as i64)
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{thought::PgThoughtRepository, user::PgUserRepository};
+    use domain::ports::{ThoughtRepository, UserWriter};
+    use domain::{
+        models::{
+            thought::{Thought, Visibility},
+            user::User,
+        },
+        value_objects::*,
+    };
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn find_or_create_tag(pool: sqlx::PgPool) {
+        let repo = PgTagRepository::new(pool);
+        let t1 = repo.find_or_create("rust").await.unwrap();
+        let t2 = repo.find_or_create("rust").await.unwrap();
+        assert_eq!(t1.id, t2.id);
+        assert_eq!(t1.name, "rust");
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn attach_and_list(pool: sqlx::PgPool) {
+        let urepo = PgUserRepository::new(pool.clone());
+        let trepo = PgThoughtRepository::new(pool.clone());
+        let u = User::new_local(
+            UserId::new(),
+            Username::new("alice").unwrap(),
+            Email::new("alice@ex.com").unwrap(),
+            PasswordHash("h".into()),
+        );
+        urepo.save(&u).await.unwrap();
+        let t = Thought::new_local(
+            ThoughtId::new(),
+            u.id.clone(),
+            Content::new_local("hi").unwrap(),
+            None,
+            Visibility::Public,
+            None,
+            false,
+        );
+        trepo.save(&t).await.unwrap();
+        let repo = PgTagRepository::new(pool);
+        let tag = repo.find_or_create("greetings").await.unwrap();
+        repo.attach_to_thought(&t.id, tag.id).await.unwrap();
+        let tags = repo.list_for_thought(&t.id).await.unwrap();
+        assert_eq!(tags.len(), 1);
+        assert_eq!(tags[0].name, "greetings");
+    }
+}

crates/adapters/postgres/src/test_helpers.rs

@@ -0,0 +1,37 @@
+use crate::{thought::PgThoughtRepository, user::PgUserRepository};
+use domain::{
+    models::{
+        thought::{Thought, Visibility},
+        user::User,
+    },
+    ports::{ThoughtRepository, UserWriter},
+    value_objects::{Content, Email, PasswordHash, ThoughtId, UserId, Username},
+};
+
+pub async fn seed_user(pool: &sqlx::PgPool, username: &str, email: &str) -> User {
+    let repo = PgUserRepository::new(pool.clone());
+    let u = User::new_local(
+        UserId::new(),
+        Username::new(username).unwrap(),
+        Email::new(email).unwrap(),
+        PasswordHash("h".into()),
+    );
+    repo.save(&u).await.unwrap();
+    u
+}
+
+pub async fn seed_user_and_thought(pool: &sqlx::PgPool) -> (User, Thought) {
+    let user = seed_user(pool, "alice", "alice@ex.com").await;
+    let trepo = PgThoughtRepository::new(pool.clone());
+    let t = Thought::new_local(
+        ThoughtId::new(),
+        user.id.clone(),
+        Content::new_local("hi").unwrap(),
+        None,
+        Visibility::Public,
+        None,
+        false,
+    );
+    trepo.save(&t).await.unwrap();
+    (user, t)
+}

crates/adapters/postgres/src/thought.rs

@@ -0,0 +1,262 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use chrono::{DateTime, Utc};
+
+use domain::{
+    errors::DomainError,
+    models::{
+        feed::{PageParams, Paginated},
+        thought::{Thought, Visibility},
+    },
+    ports::ThoughtRepository,
+    value_objects::{Content, ThoughtId, UserId},
+};
+use sqlx::PgPool;
+
+pub struct PgThoughtRepository {
+    pool: PgPool,
+}
+impl PgThoughtRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[derive(sqlx::FromRow)]
+pub(crate) struct ThoughtRow {
+    pub id: uuid::Uuid,
+    pub user_id: uuid::Uuid,
+    pub content: String,
+    pub in_reply_to_id: Option<uuid::Uuid>,
+    pub visibility: String,
+    pub content_warning: Option<String>,
+    pub sensitive: bool,
+    pub local: bool,
+    pub created_at: DateTime<Utc>,
+    pub updated_at: Option<DateTime<Utc>>,
+}
+
+impl TryFrom<ThoughtRow> for Thought {
+    type Error = DomainError;
+    fn try_from(r: ThoughtRow) -> Result<Self, DomainError> {
+        Ok(Thought {
+            id: ThoughtId::from_uuid(r.id),
+            user_id: UserId::from_uuid(r.user_id),
+            content: Content::new_remote(r.content),
+            in_reply_to_id: r.in_reply_to_id.map(ThoughtId::from_uuid),
+            visibility: Visibility::from_db_str(&r.visibility)?,
+            content_warning: r.content_warning,
+            sensitive: r.sensitive,
+            local: r.local,
+            created_at: r.created_at,
+            updated_at: r.updated_at,
+        })
+    }
+}
+
+const THOUGHT_SELECT: &str =
+    "SELECT id,user_id,content,in_reply_to_id,visibility,content_warning,sensitive,local,created_at,updated_at FROM thoughts";
+
+#[async_trait]
+impl ThoughtRepository for PgThoughtRepository {
+    async fn save(&self, t: &Thought) -> Result<(), DomainError> {
+        sqlx::query(
+            "INSERT INTO thoughts(id,user_id,content,in_reply_to_id,visibility,content_warning,sensitive,local,created_at)
+             VALUES($1,$2,$3,$4,$5,$6,$7,$8,$9)
+             ON CONFLICT(id) DO UPDATE SET content=EXCLUDED.content,updated_at=NOW()"
+        )
+        .bind(t.id.as_uuid())
+        .bind(t.user_id.as_uuid())
+        .bind(t.content.as_str())
+        .bind(t.in_reply_to_id.as_ref().map(|x| x.as_uuid()))
+        .bind(t.visibility.as_str())
+        .bind(&t.content_warning)
+        .bind(t.sensitive)
+        .bind(t.local)
+        .bind(t.created_at)
+        .execute(&self.pool)
+        .await
+        .into_domain()
+        .map(|_| ())
+    }
+
+    async fn find_by_id(&self, id: &ThoughtId) -> Result<Option<Thought>, DomainError> {
+        sqlx::query_as::<_, ThoughtRow>(&format!("{THOUGHT_SELECT} WHERE id=$1"))
+            .bind(id.as_uuid())
+            .fetch_optional(&self.pool)
+            .await
+            .into_domain()
+            .and_then(|o| o.map(Thought::try_from).transpose())
+    }
+
+    async fn delete(&self, id: &ThoughtId, user_id: &UserId) -> Result<(), DomainError> {
+        let r = sqlx::query("DELETE FROM thoughts WHERE id=$1 AND user_id=$2")
+            .bind(id.as_uuid())
+            .bind(user_id.as_uuid())
+            .execute(&self.pool)
+            .await
+            .into_domain()?;
+        if r.rows_affected() == 0 {
+            return Err(DomainError::NotFound);
+        }
+        Ok(())
+    }
+
+    async fn update_content(&self, id: &ThoughtId, content: &Content) -> Result<(), DomainError> {
+        sqlx::query("UPDATE thoughts SET content=$2,updated_at=NOW() WHERE id=$1")
+            .bind(id.as_uuid())
+            .bind(content.as_str())
+            .execute(&self.pool)
+            .await
+            .into_domain()
+            .map(|_| ())
+    }
+
+    async fn get_thread(&self, id: &ThoughtId) -> Result<Vec<Thought>, DomainError> {
+        // Recursive CTE: fetches the root thought and all nested replies at any depth.
+        sqlx::query_as::<_, ThoughtRow>(
+            "WITH RECURSIVE thread AS (
+                SELECT id,user_id,content,in_reply_to_id,
+                       visibility,content_warning,sensitive,local,created_at,updated_at
+                FROM thoughts WHERE id = $1
+                UNION ALL
+                SELECT t.id,t.user_id,t.content,t.in_reply_to_id,
+                       t.visibility,t.content_warning,t.sensitive,t.local,t.created_at,t.updated_at
+                FROM thoughts t JOIN thread ON t.in_reply_to_id = thread.id
+            )
+            SELECT * FROM thread ORDER BY created_at ASC",
+        )
+        .bind(id.as_uuid())
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()
+        .and_then(|rows| rows.into_iter().map(Thought::try_from).collect())
+    }
+
+    async fn list_by_user(
+        &self,
+        user_id: &UserId,
+        page: &PageParams,
+    ) -> Result<Paginated<Thought>, DomainError> {
+        let uid = user_id.as_uuid();
+        let total: i64 = sqlx::query_scalar("SELECT COUNT(*) FROM thoughts WHERE user_id = $1")
+            .bind(uid)
+            .fetch_one(&self.pool)
+            .await
+            .into_domain()?;
+
+        let rows = sqlx::query_as::<_, ThoughtRow>(&format!(
+            "{THOUGHT_SELECT} WHERE user_id=$1 ORDER BY created_at DESC LIMIT $2 OFFSET $3"
+        ))
+        .bind(uid)
+        .bind(page.limit())
+        .bind(page.offset())
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()?;
+
+        Ok(Paginated {
+            items: rows
+                .into_iter()
+                .map(Thought::try_from)
+                .collect::<Result<Vec<_>, _>>()?,
+            total,
+            page: page.page,
+            per_page: page.per_page,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_helpers::seed_user;
+    use domain::{
+        models::thought::{Thought, Visibility},
+        value_objects::*,
+    };
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn save_and_find_thought(pool: sqlx::PgPool) {
+        let user = seed_user(&pool, "alice", "alice@ex.com").await;
+        let repo = PgThoughtRepository::new(pool);
+        let t = Thought::new_local(
+            ThoughtId::new(),
+            user.id.clone(),
+            Content::new_local("hello world").unwrap(),
+            None,
+            Visibility::Public,
+            None,
+            false,
+        );
+        repo.save(&t).await.unwrap();
+        let found = repo.find_by_id(&t.id).await.unwrap().unwrap();
+        assert_eq!(found.content.as_str(), "hello world");
+        assert!(found.local);
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn delete_thought(pool: sqlx::PgPool) {
+        let user = seed_user(&pool, "bob", "bob@ex.com").await;
+        let repo = PgThoughtRepository::new(pool);
+        let t = Thought::new_local(
+            ThoughtId::new(),
+            user.id.clone(),
+            Content::new_local("bye").unwrap(),
+            None,
+            Visibility::Public,
+            None,
+            false,
+        );
+        repo.save(&t).await.unwrap();
+        repo.delete(&t.id, &user.id).await.unwrap();
+        assert!(repo.find_by_id(&t.id).await.unwrap().is_none());
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn delete_wrong_owner_returns_not_found(pool: sqlx::PgPool) {
+        let alice = seed_user(&pool, "alice", "alice@ex.com").await;
+        let bob = seed_user(&pool, "bob", "bob@ex.com").await;
+        let repo = PgThoughtRepository::new(pool);
+        let t = Thought::new_local(
+            ThoughtId::new(),
+            alice.id.clone(),
+            Content::new_local("secret").unwrap(),
+            None,
+            Visibility::Public,
+            None,
+            false,
+        );
+        repo.save(&t).await.unwrap();
+        let err = repo.delete(&t.id, &bob.id).await.unwrap_err();
+        assert!(matches!(err, DomainError::NotFound));
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn get_thread_returns_root_and_replies(pool: sqlx::PgPool) {
+        let user = seed_user(&pool, "charlie", "charlie@ex.com").await;
+        let repo = PgThoughtRepository::new(pool);
+        let root = Thought::new_local(
+            ThoughtId::new(),
+            user.id.clone(),
+            Content::new_local("root").unwrap(),
+            None,
+            Visibility::Public,
+            None,
+            false,
+        );
+        let reply = Thought::new_local(
+            ThoughtId::new(),
+            user.id.clone(),
+            Content::new_local("reply").unwrap(),
+            Some(root.id.clone()),
+            Visibility::Public,
+            None,
+            false,
+        );
+        repo.save(&root).await.unwrap();
+        repo.save(&reply).await.unwrap();
+        let thread = repo.get_thread(&root.id).await.unwrap();
+        assert_eq!(thread.len(), 2);
+    }
+}

crates/adapters/postgres/src/top_friend.rs

@@ -0,0 +1,155 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use domain::{
+    errors::DomainError,
+    models::{top_friend::TopFriend, user::User},
+    ports::TopFriendRepository,
+    value_objects::UserId,
+};
+use sqlx::PgPool;
+
+pub struct PgTopFriendRepository {
+    pool: PgPool,
+}
+impl PgTopFriendRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl TopFriendRepository for PgTopFriendRepository {
+    async fn set_top_friends(
+        &self,
+        user_id: &UserId,
+        friends: Vec<(UserId, i16)>,
+    ) -> Result<(), DomainError> {
+        let mut tx = self.pool.begin().await.into_domain()?;
+        sqlx::query("DELETE FROM top_friends WHERE user_id=$1")
+            .bind(user_id.as_uuid())
+            .execute(&mut *tx)
+            .await
+            .into_domain()?;
+        for (friend_id, pos) in friends {
+            sqlx::query("INSERT INTO top_friends(user_id,friend_id,position) VALUES($1,$2,$3)")
+                .bind(user_id.as_uuid())
+                .bind(friend_id.as_uuid())
+                .bind(pos)
+                .execute(&mut *tx)
+                .await
+                .into_domain()?;
+        }
+        tx.commit().await.into_domain()
+    }
+
+    async fn list_for_user(&self, user_id: &UserId) -> Result<Vec<(TopFriend, User)>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            tf_user_id: uuid::Uuid,
+            friend_id: uuid::Uuid,
+            position: i16,
+            id: uuid::Uuid,
+            username: String,
+            email: String,
+            password_hash: String,
+            display_name: Option<String>,
+            bio: Option<String>,
+            avatar_url: Option<String>,
+            header_url: Option<String>,
+            custom_css: Option<String>,
+            local: bool,
+            created_at: chrono::DateTime<chrono::Utc>,
+            updated_at: chrono::DateTime<chrono::Utc>,
+        }
+        let rows = sqlx::query_as::<_, Row>(
+            "SELECT tf.user_id AS tf_user_id, tf.friend_id, tf.position,
+             u.id, u.username, u.email, u.password_hash, u.display_name, u.bio,
+             u.avatar_url, u.header_url, u.custom_css, u.local,
+             u.created_at, u.updated_at
+             FROM top_friends tf JOIN users u ON u.id=tf.friend_id
+             WHERE tf.user_id=$1 ORDER BY tf.position",
+        )
+        .bind(user_id.as_uuid())
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()?;
+
+        Ok(rows
+            .into_iter()
+            .map(|r| {
+                use domain::value_objects::{Email, PasswordHash, Username};
+                let tf = TopFriend {
+                    user_id: UserId::from_uuid(r.tf_user_id),
+                    friend_id: UserId::from_uuid(r.friend_id),
+                    position: r.position,
+                };
+                let u = User {
+                    id: UserId::from_uuid(r.id),
+                    username: Username::from_trusted(r.username),
+                    email: Email::from_trusted(r.email),
+                    password_hash: PasswordHash(r.password_hash),
+                    display_name: r.display_name,
+                    bio: r.bio,
+                    avatar_url: r.avatar_url,
+                    header_url: r.header_url,
+                    custom_css: r.custom_css,
+                    local: r.local,
+                    created_at: r.created_at,
+                    updated_at: r.updated_at,
+                };
+                (tf, u)
+            })
+            .collect())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::user::PgUserRepository;
+    use domain::ports::UserWriter;
+    use domain::{models::user::User, value_objects::*};
+
+    async fn seed_user(pool: &sqlx::PgPool, username: &str, email: &str) -> User {
+        let repo = PgUserRepository::new(pool.clone());
+        let u = User::new_local(
+            UserId::new(),
+            Username::new(username).unwrap(),
+            Email::new(email).unwrap(),
+            PasswordHash("h".into()),
+        );
+        repo.save(&u).await.unwrap();
+        u
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn set_and_list_top_friends(pool: sqlx::PgPool) {
+        let alice = seed_user(&pool, "alice", "alice@ex.com").await;
+        let bob = seed_user(&pool, "bob", "bob@ex.com").await;
+        let repo = PgTopFriendRepository::new(pool);
+        repo.set_top_friends(&alice.id, vec![(bob.id.clone(), 1)])
+            .await
+            .unwrap();
+        let friends = repo.list_for_user(&alice.id).await.unwrap();
+        assert_eq!(friends.len(), 1);
+        assert_eq!(friends[0].0.position, 1);
+        assert_eq!(friends[0].1.username.as_str(), "bob");
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn replace_top_friends(pool: sqlx::PgPool) {
+        let alice = seed_user(&pool, "alice", "alice@ex.com").await;
+        let bob = seed_user(&pool, "bob", "bob@ex.com").await;
+        let carol = seed_user(&pool, "carol", "carol@ex.com").await;
+        let repo = PgTopFriendRepository::new(pool);
+        repo.set_top_friends(&alice.id, vec![(bob.id.clone(), 1)])
+            .await
+            .unwrap();
+        repo.set_top_friends(&alice.id, vec![(carol.id.clone(), 1)])
+            .await
+            .unwrap();
+        let friends = repo.list_for_user(&alice.id).await.unwrap();
+        assert_eq!(friends.len(), 1);
+        assert_eq!(friends[0].1.username.as_str(), "carol");
+    }
+}

crates/adapters/postgres/src/user.rs

@@ -0,0 +1,352 @@
+use crate::db_error::IntoDbResult;
+use async_trait::async_trait;
+use chrono::{DateTime, Utc};
+use domain::{
+    errors::DomainError,
+    models::feed::{PageParams, Paginated, UserSummary},
+    models::user::User,
+    ports::{UserReader, UserWriter},
+    value_objects::{Email, PasswordHash, UserId, Username},
+};
+use sqlx::PgPool;
+use std::collections::HashMap;
+
+pub struct PgUserRepository {
+    pool: PgPool,
+}
+impl PgUserRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
+
+#[derive(sqlx::FromRow)]
+pub struct UserRow {
+    pub id: uuid::Uuid,
+    pub username: String,
+    pub email: String,
+    pub password_hash: String,
+    pub display_name: Option<String>,
+    pub bio: Option<String>,
+    pub avatar_url: Option<String>,
+    pub header_url: Option<String>,
+    pub custom_css: Option<String>,
+    pub local: bool,
+    pub created_at: DateTime<Utc>,
+    pub updated_at: DateTime<Utc>,
+}
+
+impl From<UserRow> for User {
+    fn from(r: UserRow) -> Self {
+        User {
+            id: UserId::from_uuid(r.id),
+            username: Username::from_trusted(r.username),
+            email: Email::from_trusted(r.email),
+            password_hash: PasswordHash(r.password_hash),
+            display_name: r.display_name,
+            bio: r.bio,
+            avatar_url: r.avatar_url,
+            header_url: r.header_url,
+            custom_css: r.custom_css,
+            local: r.local,
+            created_at: r.created_at,
+            updated_at: r.updated_at,
+        }
+    }
+}
+
+pub const USER_SELECT: &str =
+    "SELECT id,username,email,password_hash,display_name,bio,avatar_url,header_url,\
+     custom_css,local,created_at,updated_at FROM users";
+
+#[async_trait]
+impl UserReader for PgUserRepository {
+    async fn find_by_id(&self, id: &UserId) -> Result<Option<User>, DomainError> {
+        sqlx::query_as::<_, UserRow>(&format!("{USER_SELECT} WHERE id=$1"))
+            .bind(id.as_uuid())
+            .fetch_optional(&self.pool)
+            .await
+            .into_domain()
+            .map(|o| o.map(User::from))
+    }
+
+    async fn find_by_username(&self, username: &Username) -> Result<Option<User>, DomainError> {
+        sqlx::query_as::<_, UserRow>(&format!("{USER_SELECT} WHERE username=$1"))
+            .bind(username.as_str())
+            .fetch_optional(&self.pool)
+            .await
+            .into_domain()
+            .map(|o| o.map(User::from))
+    }
+
+    async fn find_by_email(&self, email: &Email) -> Result<Option<User>, DomainError> {
+        sqlx::query_as::<_, UserRow>(&format!("{USER_SELECT} WHERE email=$1"))
+            .bind(email.as_str())
+            .fetch_optional(&self.pool)
+            .await
+            .into_domain()
+            .map(|o| o.map(User::from))
+    }
+
+    async fn list_with_stats(&self) -> Result<Vec<UserSummary>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            id: uuid::Uuid,
+            username: String,
+            display_name: Option<String>,
+            avatar_url: Option<String>,
+            bio: Option<String>,
+            thought_count: i64,
+            follower_count: i64,
+            following_count: i64,
+        }
+        let rows = sqlx::query_as::<_, Row>(
+            "SELECT u.id, u.username, u.display_name, u.avatar_url, u.bio,
+             COUNT(DISTINCT t.id) AS thought_count,
+             COUNT(DISTINCT f1.follower_id) AS follower_count,
+             COUNT(DISTINCT f2.following_id) AS following_count
+             FROM users u
+             LEFT JOIN thoughts t ON t.user_id=u.id AND t.local=true
+             LEFT JOIN follows f1 ON f1.following_id=u.id AND f1.state='accepted'
+             LEFT JOIN follows f2 ON f2.follower_id=u.id AND f2.state='accepted'
+             WHERE u.local=true
+             GROUP BY u.id
+             ORDER BY u.username",
+        )
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()?;
+
+        Ok(rows
+            .into_iter()
+            .map(|r| UserSummary {
+                id: UserId::from_uuid(r.id),
+                username: r.username,
+                display_name: r.display_name,
+                avatar_url: r.avatar_url,
+                bio: r.bio,
+                thought_count: r.thought_count,
+                follower_count: r.follower_count,
+                following_count: r.following_count,
+            })
+            .collect())
+    }
+
+    async fn count(&self) -> Result<i64, DomainError> {
+        sqlx::query_scalar::<_, i64>("SELECT COUNT(*) FROM users WHERE local = true")
+            .fetch_one(&self.pool)
+            .await
+            .into_domain()
+    }
+
+    async fn list_paginated(&self, page: PageParams) -> Result<Paginated<UserSummary>, DomainError> {
+        #[derive(sqlx::FromRow)]
+        struct Row {
+            id: uuid::Uuid,
+            username: String,
+            display_name: Option<String>,
+            avatar_url: Option<String>,
+            bio: Option<String>,
+            thought_count: i64,
+            follower_count: i64,
+            following_count: i64,
+            total: i64,
+        }
+        let rows = sqlx::query_as::<_, Row>(
+            "SELECT u.id, u.username, u.display_name, u.avatar_url, u.bio,
+             COUNT(DISTINCT t.id) AS thought_count,
+             COUNT(DISTINCT f1.follower_id) AS follower_count,
+             COUNT(DISTINCT f2.following_id) AS following_count,
+             COUNT(*) OVER() AS total
+             FROM users u
+             LEFT JOIN thoughts t ON t.user_id=u.id AND t.local=true
+             LEFT JOIN follows f1 ON f1.following_id=u.id AND f1.state='accepted'
+             LEFT JOIN follows f2 ON f2.follower_id=u.id AND f2.state='accepted'
+             WHERE u.local=true
+             GROUP BY u.id
+             ORDER BY u.username
+             LIMIT $1 OFFSET $2",
+        )
+        .bind(page.limit())
+        .bind(page.offset())
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()?;
+
+        let total = rows.first().map(|r| r.total).unwrap_or(0);
+        let items = rows
+            .into_iter()
+            .map(|r| UserSummary {
+                id: UserId::from_uuid(r.id),
+                username: r.username,
+                display_name: r.display_name,
+                avatar_url: r.avatar_url,
+                bio: r.bio,
+                thought_count: r.thought_count,
+                follower_count: r.follower_count,
+                following_count: r.following_count,
+            })
+            .collect();
+        Ok(Paginated { items, total, page: page.page, per_page: page.per_page })
+    }
+
+    async fn find_by_ids(&self, ids: &[UserId]) -> Result<HashMap<UserId, User>, DomainError> {
+        if ids.is_empty() {
+            return Ok(HashMap::new());
+        }
+        let uuids: Vec<uuid::Uuid> = ids.iter().map(|id| id.as_uuid()).collect();
+        let rows = sqlx::query_as::<_, UserRow>(
+            &format!("{USER_SELECT} WHERE id = ANY($1)")
+        )
+        .bind(&uuids[..])
+        .fetch_all(&self.pool)
+        .await
+        .into_domain()?;
+
+        Ok(rows.into_iter().map(|r| {
+            let user = User::from(r);
+            (user.id.clone(), user)
+        }).collect())
+    }
+}
+
+#[async_trait]
+impl UserWriter for PgUserRepository {
+    async fn save(&self, user: &User) -> Result<(), DomainError> {
+        sqlx::query(
+            "INSERT INTO users (id,username,email,password_hash,display_name,bio,avatar_url,header_url,custom_css,local,created_at,updated_at)
+             VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12)
+             ON CONFLICT(id) DO UPDATE SET
+               username=EXCLUDED.username, email=EXCLUDED.email,
+               password_hash=EXCLUDED.password_hash, display_name=EXCLUDED.display_name,
+               bio=EXCLUDED.bio, avatar_url=EXCLUDED.avatar_url,
+               header_url=EXCLUDED.header_url, custom_css=EXCLUDED.custom_css,
+               local=EXCLUDED.local,
+               updated_at=NOW()"
+        )
+        .bind(user.id.as_uuid())
+        .bind(user.username.as_str())
+        .bind(user.email.as_str())
+        .bind(&user.password_hash.0)
+        .bind(&user.display_name)
+        .bind(&user.bio)
+        .bind(&user.avatar_url)
+        .bind(&user.header_url)
+        .bind(&user.custom_css)
+        .bind(user.local)
+        .bind(user.created_at)
+        .bind(user.updated_at)
+        .execute(&self.pool)
+        .await
+        .map_err(|e| {
+            if let sqlx::Error::Database(ref db) = e {
+                if db.code().as_deref() == Some("23505") {
+                    return match db.constraint().unwrap_or("") {
+                        "users_username_key" => DomainError::UniqueViolation { field: "username" },
+                        "users_email_key"    => DomainError::UniqueViolation { field: "email" },
+                        _                   => DomainError::UniqueViolation { field: "unknown" },
+                    };
+                }
+            }
+            DomainError::Internal(e.to_string())
+        })
+        .map(|_| ())
+    }
+
+    async fn update_profile(
+        &self,
+        user_id: &UserId,
+        display_name: Option<String>,
+        bio: Option<String>,
+        avatar_url: Option<String>,
+        header_url: Option<String>,
+        custom_css: Option<String>,
+    ) -> Result<(), DomainError> {
+        sqlx::query(
+            "UPDATE users SET display_name=$2,bio=$3,avatar_url=$4,header_url=$5,custom_css=$6,updated_at=NOW() WHERE id=$1"
+        )
+        .bind(user_id.as_uuid())
+        .bind(display_name)
+        .bind(bio)
+        .bind(avatar_url)
+        .bind(header_url)
+        .bind(custom_css)
+        .execute(&self.pool)
+        .await
+        .into_domain()
+        .map(|_| ())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use domain::{models::user::User, value_objects::*};
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn save_and_find_by_id(pool: sqlx::PgPool) {
+        let repo = PgUserRepository::new(pool);
+        let user = User::new_local(
+            UserId::new(),
+            Username::new("alice").unwrap(),
+            Email::new("alice@ex.com").unwrap(),
+            PasswordHash("hash".into()),
+        );
+        repo.save(&user).await.unwrap();
+        let found = repo.find_by_id(&user.id).await.unwrap().unwrap();
+        assert_eq!(found.username.as_str(), "alice");
+        assert_eq!(found.email.as_str(), "alice@ex.com");
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn find_by_username_returns_none_when_missing(pool: sqlx::PgPool) {
+        let repo = PgUserRepository::new(pool);
+        let result = repo
+            .find_by_username(&Username::new("ghost").unwrap())
+            .await
+            .unwrap();
+        assert!(result.is_none());
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn find_by_email(pool: sqlx::PgPool) {
+        let repo = PgUserRepository::new(pool);
+        let user = User::new_local(
+            UserId::new(),
+            Username::new("bob").unwrap(),
+            Email::new("bob@ex.com").unwrap(),
+            PasswordHash("hash".into()),
+        );
+        repo.save(&user).await.unwrap();
+        let found = repo
+            .find_by_email(&Email::new("bob@ex.com").unwrap())
+            .await
+            .unwrap();
+        assert!(found.is_some());
+    }
+
+    #[sqlx::test(migrations = "./migrations")]
+    async fn update_profile_changes_fields(pool: sqlx::PgPool) {
+        let repo = PgUserRepository::new(pool);
+        let user = User::new_local(
+            UserId::new(),
+            Username::new("charlie").unwrap(),
+            Email::new("charlie@ex.com").unwrap(),
+            PasswordHash("hash".into()),
+        );
+        repo.save(&user).await.unwrap();
+        repo.update_profile(
+            &user.id,
+            Some("Charlie".into()),
+            Some("bio".into()),
+            None,
+            None,
+            None,
+        )
+        .await
+        .unwrap();
+        let found = repo.find_by_id(&user.id).await.unwrap().unwrap();
+        assert_eq!(found.display_name.as_deref(), Some("Charlie"));
+        assert_eq!(found.bio.as_deref(), Some("bio"));
+    }
+}