Add account browsing simulation

docs/data-flow.md

@@ -60,6 +60,12 @@ Every runtime shares one `RedditRequestCoordinator`, because Reddit can enforce
 
 Do not add local retries around this layer without preserving the shared schedule. Per-account bursts defeat the coordinator.
 
+## Browsing simulation flow
+
+After reply handling, response checks, and comment-growth work, an enabled account may run one due browsing simulation session. The durable `next_due_at` gate survives restarts; a deterministic per-account daily target and randomized waking-hours spacing avoid recalculating a flapping schedule on each minute tick. The session picks one configured growth community by weight, reads its hot listing through the shared Reddit request coordinator, optionally reads typed top-level comments, applies deterministic exclusions, and only then selects randomly.
+
+The terminal operation records `simulated-upvote` in SQLite and operator activity. There is no vote endpoint or Reddit write dependency. Scan, running, and browser dry-run all perform the same simulation; stopped mode performs no discovery or decision work. Reddit 429 responses extend the shared cooldown, while ordinary read failures remain isolated from replies and comment growth.
+
 ## Reply-first conversation automation
 
 Explicit bot clients can send to a username through `POST /api/v1/messages` or the MCP `send_message_to_user` tool without selecting an account. The selector compares cached conversations case-insensitively and reuses the account that most recently interacted with that recipient. If no conversation exists, it chooses an authenticated running account with no invitation cooldown, preferring the lowest hourly send count. The selected account's normal rate limiter still owns the send. An API reply to an existing conversation marks automation as user-overridden so autonomous replies do not race the external caller.