fix: scope live revisions to worker generations (#383)

src/main.py

@@ -2,6 +2,7 @@ import asyncio
 import hmac
 import math
 import os
+import secrets
 import sqlite3
 import time
 from collections.abc import Awaitable, Coroutine
@@ -108,6 +109,7 @@ _live_snapshot_refreshing_sections: set[str] = set()
 _live_section_revisions: dict[str, int] = {
     section: 0 for section in LIVE_SNAPSHOT_SECTIONS
 }
+_live_revision_generation = secrets.token_hex(8)
 _read_notification_ids: set[int] = set()
 _authored_action_operations: dict[
     str, tuple[tuple[Any, ...], asyncio.Task, float]
@@ -1584,7 +1586,7 @@ def _live_snapshot_payload(
     *,
     stale: bool,
     revalidating: bool,
-    known_revisions: dict[str, int | None] | None = None,
+    known_revisions: dict[str, str | None] | None = None,
 ) -> dict:
     payload = dict(value)
     now = time.monotonic()
@@ -1617,9 +1619,13 @@ def _live_snapshot_payload(
         "retry_in_seconds": min(retries, default=0),
         "sections": section_freshness,
     }
-    payload["revisions"] = dict(_live_section_revisions)
+    revision_tokens = {
+        section: f"{_live_revision_generation}.{revision}"
+        for section, revision in _live_section_revisions.items()
+    }
+    payload["revisions"] = revision_tokens
     for section, known_revision in (known_revisions or {}).items():
-        if known_revision is None or known_revision != _live_section_revisions[section]:
+        if known_revision is None or known_revision != revision_tokens[section]:
             continue
         payload.pop(section, None)
         if section == "notifications":
@@ -1669,9 +1675,15 @@ def _without_read_notifications(snapshot: dict) -> dict:
 
 @app.get("/api/v1/live")
 async def live_snapshot(
-    context_revision: int | None = Query(default=None, ge=0),
-    events_revision: int | None = Query(default=None, ge=0),
-    notifications_revision: int | None = Query(default=None, ge=0),
+    context_revision: str | None = Query(
+        default=None, max_length=64, pattern=r"^[0-9a-f]{16}\.[0-9]{1,20}$"
+    ),
+    events_revision: str | None = Query(
+        default=None, max_length=64, pattern=r"^[0-9a-f]{16}\.[0-9]{1,20}$"
+    ),
+    notifications_revision: str | None = Query(
+        default=None, max_length=64, pattern=r"^[0-9a-f]{16}\.[0-9]{1,20}$"
+    ),
 ) -> JSONResponse:
     """Return a freshness-bounded snapshot and share identical upstream loads."""
     global _live_snapshot_task, _live_snapshot_value, _live_snapshot_created_at