perf: cheaper ingest — no re-parse of live hooked transcripts, delta hook writes, lighter pollers

- Session sync leaves a transcript alone while hooks feed its session live
  (active, newest event a hook's, touched within DASHBOARD_SYNC_LIVE_HOOK_MS,
  default 5 min) and catches it up once quiet; a hook-created session (which
  importSession skips anyway) is only snapshotted, never parsed.
- Hook writer keeps a per-transcript mark (applied after commit): an
  unchanged TranscriptCache result skips token/compaction/API-error/turn
  writes, a grown one walks only the entries after the last one handled.
- Codex usage: one stamp query per pass instead of one row per journal;
  between full passes (first + every 5 min) only the newest day folders and
  journals written in the last hour are statted; fork parents resolved from
  the table or a full walk.
- Cursor/Antigravity polls back off to 60 s after idle passes
  (server/lib/backoff-poll.js); lane sync runs only while another dashboard
  shares the data dir (checked every 30 s).

docs/DEPLOYMENT.md

@@ -256,9 +256,9 @@ DASHBOARD_DB_PATH=/var/lib/agenthub/dashboard.db
 DASHBOARD_WORKFLOW_POLL_MS=12000        # Workflow-tool run journals
 DASHBOARD_CODEX_POLL_MS=15000           # Codex rollout journals → codex lane running/idle + Codex sessions/tokens
 CODEX_HOME=                             # where Codex keeps sessions/ (default ~/.codex)
-DASHBOARD_ANTIGRAVITY_POLL_MS=15000     # agy conversation files → Antigravity sessions/tokens
+DASHBOARD_ANTIGRAVITY_POLL_MS=15000     # agy conversation files → Antigravity sessions/tokens (60 s while idle)
 AGENTHUB_GEMINI_DIR=                    # where agy keeps its data (default ~/.gemini)
-DASHBOARD_CURSOR_POLL_MS=15000          # Cursor agent transcripts → Cursor sessions (no tokens)
+DASHBOARD_CURSOR_POLL_MS=15000          # Cursor agent transcripts → Cursor sessions (no tokens; 60 s while idle)
 AGENTHUB_CURSOR_DIR=                    # where Cursor keeps its data (default ~/.cursor)
 AGENTHUB_AGY_USAGE=                     # 0 never runs `agy --print /usage` for the Usage panel's Antigravity quota (default on; running agy may update it)
 

docs/HOOKS.md

@@ -491,7 +491,8 @@ graph TB
 >    entry whose PID is no longer alive** and POSTs the hook payload to one
 >    port per **unique SQLite data directory** (lowest port wins when two
 >    instances share `~/.claude/agenthub`). The other instance re-broadcasts
->    the workspaces those hooks moved within `DASHBOARD_LANE_SYNC_MS` (2 s), so its
+>    the workspaces those hooks moved within `DASHBOARD_LANE_SYNC_MS` (2 s; a server
+>    alone on its data dir only looks for such a peer every 30 s), so its
 >    browsers see a workspace's status without a refresh.
 > 3. If neither yields a target, the handler falls back to `4820`.
 >
@@ -589,6 +590,7 @@ Claude Code waits only for the handler process: Node start-up, reading stdin, se
 
 - **Fire-and-forget POST** — no wait for the dashboard's reply.
 - **Incremental transcript reads** — `TranscriptCache` reads only the bytes appended since the last hook.
+- **Only new transcript entries are written** — a per-transcript mark (`transcriptMarks` in `server/routes/hooks.js`, set once the hook's transaction commits) skips the token, compaction, API-error and turn-duration writes when the transcript did not change, and walks only the entries after the last one handled when it grew.
 - **One POST per database, not per server** — servers sharing a database get each event once (`resolveHookIngestPorts`).
 - **Heavy reads off the event loop** — aggregates run in a worker (`server/lib/read-pool.js`), so a slow page never delays ingest.