Add format_date helper to handle datetime objects in templates

The db now returns datetime objects instead of strings in some cases.
Added format_date() helper function that handles both datetime and string
values, and replaced all [:10] date slicing with calls to this helper.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

db.py

@@ -72,7 +72,22 @@ CREATE TABLE IF NOT EXISTS activities (
     actor_id TEXT NOT NULL,
     object_data JSONB NOT NULL,
     published TIMESTAMPTZ NOT NULL,
-    signature JSONB
+    signature JSONB,
+    anchor_root VARCHAR(64)  -- Merkle root this activity is anchored to
+);
+
+-- Anchors table (Bitcoin timestamps via OpenTimestamps)
+CREATE TABLE IF NOT EXISTS anchors (
+    id SERIAL PRIMARY KEY,
+    merkle_root VARCHAR(64) NOT NULL UNIQUE,
+    tree_ipfs_cid VARCHAR(128),
+    ots_proof_cid VARCHAR(128),
+    activity_count INTEGER NOT NULL,
+    first_activity_id UUID,
+    last_activity_id UUID,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    confirmed_at TIMESTAMPTZ,
+    bitcoin_txid VARCHAR(64)
 );
 
 -- Followers table
@@ -94,6 +109,8 @@ CREATE INDEX IF NOT EXISTS idx_assets_created_at ON assets(created_at DESC);
 CREATE INDEX IF NOT EXISTS idx_assets_tags ON assets USING GIN(tags);
 CREATE INDEX IF NOT EXISTS idx_activities_actor_id ON activities(actor_id);
 CREATE INDEX IF NOT EXISTS idx_activities_published ON activities(published DESC);
+CREATE INDEX IF NOT EXISTS idx_activities_anchor ON activities(anchor_root);
+CREATE INDEX IF NOT EXISTS idx_anchors_created ON anchors(created_at DESC);
 CREATE INDEX IF NOT EXISTS idx_followers_username ON followers(username);
 """
 
@@ -567,3 +584,120 @@ async def get_stats() -> dict:
         activities = await conn.fetchval("SELECT COUNT(*) FROM activities")
         users = await conn.fetchval("SELECT COUNT(*) FROM users")
         return {"assets": assets, "activities": activities, "users": users}
+
+
+# ============ Anchors (Bitcoin timestamps) ============
+
+async def get_unanchored_activities() -> list[dict]:
+    """Get all activities not yet anchored to Bitcoin."""
+    async with get_connection() as conn:
+        rows = await conn.fetch(
+            """SELECT activity_id, activity_type, actor_id, object_data, published, signature
+               FROM activities WHERE anchor_root IS NULL ORDER BY published ASC"""
+        )
+        return [_parse_activity_row(row) for row in rows]
+
+
+async def create_anchor(anchor: dict) -> dict:
+    """Create an anchor record."""
+    async with get_connection() as conn:
+        row = await conn.fetchrow(
+            """INSERT INTO anchors (merkle_root, tree_ipfs_cid, ots_proof_cid,
+                                    activity_count, first_activity_id, last_activity_id)
+               VALUES ($1, $2, $3, $4, $5, $6)
+               RETURNING *""",
+            anchor["merkle_root"],
+            anchor.get("tree_ipfs_cid"),
+            anchor.get("ots_proof_cid"),
+            anchor["activity_count"],
+            UUID(anchor["first_activity_id"]) if anchor.get("first_activity_id") else None,
+            UUID(anchor["last_activity_id"]) if anchor.get("last_activity_id") else None
+        )
+        return dict(row)
+
+
+async def mark_activities_anchored(activity_ids: list[str], merkle_root: str) -> int:
+    """Mark activities as anchored with the given merkle root."""
+    async with get_connection() as conn:
+        result = await conn.execute(
+            """UPDATE activities SET anchor_root = $1
+               WHERE activity_id = ANY($2::uuid[])""",
+            merkle_root,
+            [UUID(aid) for aid in activity_ids]
+        )
+        # Returns "UPDATE N"
+        return int(result.split()[1]) if result else 0
+
+
+async def get_anchor(merkle_root: str) -> Optional[dict]:
+    """Get anchor by merkle root."""
+    async with get_connection() as conn:
+        row = await conn.fetchrow(
+            "SELECT * FROM anchors WHERE merkle_root = $1",
+            merkle_root
+        )
+        if row:
+            result = dict(row)
+            if result.get("first_activity_id"):
+                result["first_activity_id"] = str(result["first_activity_id"])
+            if result.get("last_activity_id"):
+                result["last_activity_id"] = str(result["last_activity_id"])
+            if result.get("created_at"):
+                result["created_at"] = result["created_at"].isoformat()
+            if result.get("confirmed_at"):
+                result["confirmed_at"] = result["confirmed_at"].isoformat()
+            return result
+        return None
+
+
+async def get_all_anchors() -> list[dict]:
+    """Get all anchors, newest first."""
+    async with get_connection() as conn:
+        rows = await conn.fetch(
+            "SELECT * FROM anchors ORDER BY created_at DESC"
+        )
+        results = []
+        for row in rows:
+            result = dict(row)
+            if result.get("first_activity_id"):
+                result["first_activity_id"] = str(result["first_activity_id"])
+            if result.get("last_activity_id"):
+                result["last_activity_id"] = str(result["last_activity_id"])
+            if result.get("created_at"):
+                result["created_at"] = result["created_at"].isoformat()
+            if result.get("confirmed_at"):
+                result["confirmed_at"] = result["confirmed_at"].isoformat()
+            results.append(result)
+        return results
+
+
+async def update_anchor_confirmed(merkle_root: str, bitcoin_txid: str) -> bool:
+    """Mark anchor as confirmed with Bitcoin txid."""
+    async with get_connection() as conn:
+        result = await conn.execute(
+            """UPDATE anchors SET confirmed_at = NOW(), bitcoin_txid = $1
+               WHERE merkle_root = $2""",
+            bitcoin_txid, merkle_root
+        )
+        return result == "UPDATE 1"
+
+
+async def get_anchor_stats() -> dict:
+    """Get anchoring statistics."""
+    async with get_connection() as conn:
+        total_anchors = await conn.fetchval("SELECT COUNT(*) FROM anchors")
+        confirmed_anchors = await conn.fetchval(
+            "SELECT COUNT(*) FROM anchors WHERE confirmed_at IS NOT NULL"
+        )
+        anchored_activities = await conn.fetchval(
+            "SELECT COUNT(*) FROM activities WHERE anchor_root IS NOT NULL"
+        )
+        unanchored_activities = await conn.fetchval(
+            "SELECT COUNT(*) FROM activities WHERE anchor_root IS NULL"
+        )
+        return {
+            "total_anchors": total_anchors,
+            "confirmed_anchors": confirmed_anchors,
+            "anchored_activities": anchored_activities,
+            "unanchored_activities": unanchored_activities
+        }