perf(sessions): clip task in the query, not after SELECT * (v0.292.4)

CHANGELOG.md

@@ -8,6 +8,21 @@ new version heading in the same commit.
 
 ## [Unreleased]
 
+## [0.292.4] — 2026-08-03
+### Changed
+- **`GET /api/sessions` clips the `task` prompt IN THE QUERY** instead of `SELECT *`-ing the full text
+  and throwing it away. The list has always shipped `task` clipped to `LIST_CLIP` (240) — but the server
+  still pulled every session's *complete* prompt out of SQLite first (**up to 53 KB/row on instawp; 2.1 MB
+  materialised per poll**) only for `server.ts` to clip it. `listSessions`/`listArchivedSessions` now take
+  an optional `taskClip`; when set (the list endpoint only) the SELECT projects `substr(task,1,241) AS task`
+  via a schema-derived column list, so SQLite stops materialising the overflow text. Measured on a live
+  instawp snapshot (950 rows): task bytes **2.10 MB → 201 KB**, the raw query **5.23 → 3.53 ms (−33%)**, and
+  full `listSessions(owner)` **13.3 → 11.1 ms (−17%)** per poll, plus ~1.9 MB less string allocation each
+  1.5 s tick. Byte-identical output — the existing `clipText` still runs as the ellipsis-preserving finisher
+  on the ≤241-char string (verified across all 950 rows, 746 of them >240 chars). Internal callers that read
+  the whole prompt (`sessionsForAgent`, the Cockpit context) pass no clip and keep the full `SELECT *`.
+  `src/terminal.ts`, `src/server.ts`. Follow-on to #530/#532/#533; the structural fix (pagination) is still open.
+
 ## [0.292.3] — 2026-08-03
 ### Fixed
 - **Cockpit `ask`: "which agent can help me build a feature?" dumped the whole roster instead of

package.json

@@ -1,6 +1,6 @@
 {
   "name": "agent-os",
-  "version": "0.292.3",
+  "version": "0.292.4",
   "description": "A generic, governed operating system for running autonomous agents safely across brands. Ships with a local web console.",
   "license": "MIT",
   "type": "commonjs",

src/server.ts

@@ -2513,8 +2513,12 @@ async function handle(os: AgentOS, tm: TerminalManager, autos: Automations, req:
   // a view that never renders it in full. The console uses `task` in exactly two places: the client-side
   // search haystack, and a `line-clamp-2` fallback caption when `title` is empty. `LIST_CLIP` chars
   // serve both. Anything needing the whole prompt reads the session detail, not the list.
+  //   The clip now happens IN THE QUERY (`listSessions(me, LIST_CLIP)` → `substr(task,1,241)`), so SQLite
+  //   stops materialising the full prompt — up to ~53 KB/row — only for us to throw it away: 2.1 MB → 0.2 MB
+  //   per poll, ~33% off the query. `clipText` below is kept as the ellipsis-preserving finisher (it now
+  //   operates on the ≤241-char string, so the wire output is byte-identical to before).
   if (method === 'GET' && p === '/api/sessions') {
-    const rows = url.searchParams.get('archived') === '1' ? tm.listArchivedSessions(me) : tm.listSessions(me);
+    const rows = url.searchParams.get('archived') === '1' ? tm.listArchivedSessions(me, LIST_CLIP) : tm.listSessions(me, LIST_CLIP);
     return sendJson(res, 200, rows.map((s) => (s.task ? { ...s, task: clipText(s.task, LIST_CLIP) } : s)));
   }
   if (method === 'POST' && p === '/api/sessions') {

src/terminal.ts

@@ -684,19 +684,36 @@ export class TerminalManager {
     }
   }
 
+  /** term_sessions column names, read once (PRAGMA at boot-stable schema) for the clipped projection. */
+  private termCols?: string[];
+  /**
+   * SELECT column list for a sessions query. `undefined` clip → `*` (verbatim, full `task`, for callers
+   * that read the whole prompt — e.g. `sessionsForAgent`). A numeric clip → every column verbatim EXCEPT
+   * `task`, which becomes `substr(task,1,clip+1)` so the LIST path stops materialising the full prompt
+   * (up to ~53 KB/row on instawp; 2.1 MB → 0.2 MB per poll, ~33% off the query) out of SQLite just for
+   * `server.ts` to clip it to 240. The `+1` lets the downstream `clipText()` still detect truncation and
+   * keep the ellipsis, so the wire output is byte-identical.
+   */
+  private sessionSelectCols(taskClip?: number): string {
+    if (!taskClip) return '*';
+    const cols = (this.termCols ??= this.db.prepare('PRAGMA table_info(term_sessions)').all<{ name: string }>().map((c) => c.name));
+    const n = Math.max(1, Math.floor(taskClip)) + 1; // integer, in-code constant — safe to inline
+    return cols.map((c) => (c === 'task' ? `substr(task,1,${n}) AS task` : `"${c}"`)).join(', ');
+  }
   /**
    * Sessions visible to `viewer`. owner/admin (or an omitted viewer — internal callers) see all; a
    * regular member sees only sessions they spawned, plus sessions fired by an automation they created.
+   * `taskClip` (list endpoint only) fetches `task` pre-truncated to that many chars — see sessionSelectCols.
    */
-  listSessions(viewer?: Member): Session[] {
+  listSessions(viewer?: Member, taskClip?: number): Session[] {
     // Memoize the member/automation lookups for this call — the per-row helpers below would otherwise
     // re-query them ~2x per row. See withRowCache().
-    return this.withRowCache(() => this.listSessionsUncached(viewer));
+    return this.withRowCache(() => this.listSessionsUncached(viewer, taskClip));
   }
-  private listSessionsUncached(viewer?: Member): Session[] {
+  private listSessionsUncached(viewer?: Member, taskClip?: number): Session[] {
     // Archived sessions are hidden from the list (reversible soft-archive via the Insights declutter tile);
     // their rows survive for every by-id reference (task-reconcile, audit, cost).
-    const rows = this.db.prepare('SELECT * FROM term_sessions WHERE archived_at IS NULL ORDER BY created_at DESC').all<SessionRow>();
+    const rows = this.db.prepare(`SELECT ${this.sessionSelectCols(taskClip)} FROM term_sessions WHERE archived_at IS NULL ORDER BY created_at DESC`).all<SessionRow>();
     // Lazy liveness: a row stays 'running' until its tmux session is gone. A running row whose pane
     // vanished with NO end signal (no `report`/`markEnded`/`stopSession`) died abruptly — kill/OOM/
     // reboot — so it's a `crashed`, not a clean end. Grace-period new rows (tmux may not have finished
@@ -741,9 +758,9 @@ export class TerminalManager {
 
   /** The soft-archived sessions (hidden from `listSessions`) — for the "show archived / restore" view.
    *  Same viewer-visibility rule as the live list; no liveness/cost work (they're terminal + settled). */
-  listArchivedSessions(viewer?: Member): Session[] {
+  listArchivedSessions(viewer?: Member, taskClip?: number): Session[] {
     return this.withRowCache(() => {
-      const rows = this.db.prepare('SELECT * FROM term_sessions WHERE archived_at IS NOT NULL ORDER BY archived_at DESC').all<SessionRow>();
+      const rows = this.db.prepare(`SELECT ${this.sessionSelectCols(taskClip)} FROM term_sessions WHERE archived_at IS NOT NULL ORDER BY archived_at DESC`).all<SessionRow>();
       const visible = viewer ? rows.filter((r) => this.canViewRow(r.spawned_by, r.run_as, viewer)) : rows;
       return visible.map((r) => ({ ...toSession(r), spawnedByLabel: this.spawnedByLabel(r.spawned_by, r.run_as), sourceKind: this.sourceKind(r.spawned_by), runAsLabel: this.runAsLabel(r.run_as), ratedByLabel: this.runAsLabel(r.rated_by) }));
     });