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fix(memory): cap SessionStats turns at 200 with cost carryover#1628

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Bernardxu123:fix/session-stats-rolling-window
May 23, 2026
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fix(memory): cap SessionStats turns at 200 with cost carryover#1628
esengine merged 1 commit into
esengine:mainfrom
Bernardxu123:fix/session-stats-rolling-window

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@Bernardxu123 Bernardxu123 commented May 23, 2026 •
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Memory Leak Fix — SessionStats Rolling Window

Fixes parts of #1571

Problem

Per-turn stats array (SessionStats.turns) grows indefinitely — iterated on every summary() call. Over long sessions this causes both memory growth and O(n) cost on each summary.

Fix

Add MAX_TURNS=200 cap: when the array exceeds this, oldest turns are dropped and their costs/cache tokens folded into carryover fields. Session totals remain accurate ( otalCost, cacheHitRatio, �ggregateCacheHitRatio) while the array stays bounded.

The cap is generous — 200 turns covers a full day of active use. The carryover aggregation means resuming a session after trim still reports correct cumulative totals.

Changes

  • src/telemetry/stats.ts: Added MAX_TURNS = 200 constant and rimOldTurns() method called from
    ecord()

Testing

  • npm run lint ✅
  • npm run typecheck ✅
  • npm run test ✅ (3588 passed)

Update

Drift issue fixed — rebased on latest main. Diff now only contains src/telemetry/stats.ts.

@esengine

esengine commented May 23, 2026

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Both pieces of the original #1605 now filed cleanly (#1627 for AppendOnlyLog, this one for SessionStats) — appreciate the split. The carryover logic across _carryoverCost / _carryoverCacheHit / _carryoverCacheMiss / _carryoverTurns keeps the totalCost and cacheHitRatio getters accurate post-trim, and the record() insertion point is right. One blocker before merge: same drift pattern hitting today's PRs.

Drift

git diff origin/main..HEAD shows two extra files in the diff that aren't part of your fix:

src/cli/ui/PromptInput.tsx     |  6 +++---
src/cli/ui/cards/UserCard.tsx  |  2 +-

The change flips TONE.brand / SURFACE.bgInput back to hardcoded #0153e5 / #1e1e1e — that's #1623 (light-theme composer bg) which merged earlier today. GH says mergeStateStatus: CLEAN because git's 3-way merge sees absence-of-lines as deletion against main's additions; there are no textual conflicts to flag. Semantically merging this would undo the light-theme fix.

What to do

git fetch origin main && git rebase origin/main — your diff should narrow back to the one src/telemetry/stats.ts file. The PromptInput.tsx and UserCard.tsx lines should disappear from the diff entirely after rebase.

Same advice for #1627 — once both are rebased I'll merge them.

@Bernardxu123
fix(memory): cap SessionStats turns at 200 with cost carryover
520010d 
Per-turn stats array grows indefinitely — iterated on every
summary() call. Over long sessions this causes both memory growth
and O(n) cost on each summary.

Add MAX_TURNS=200 cap: when the array exceeds this, oldest turns
are dropped and their costs/cache tokens folded into carryover
fields. Session totals remain accurate (totalCost, cacheHitRatio)
while the array stays bounded.

The cap is generous — 200 turns covers a full day of active use.
The carryover aggregation means resuming a session after trim still
reports correct cumulative totals.
@Bernardxu123 Bernardxu123 force-pushed the fix/session-stats-rolling-window branch from 685e581 to 520010d Compare May 23, 2026 16:13
@Bernardxu123

Bernardxu123 commented May 23, 2026

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Rebased on latest main — drift cleaned up. Diff now only contains \src/telemetry/stats.ts.

@esengine esengine merged commit f12e10d into esengine:main May 23, 2026
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@Bernardxu123 Bernardxu123 deleted the fix/session-stats-rolling-window branch May 24, 2026 01:08
esengine pushed a commit that referenced this pull request May 24, 2026
chore(release): 0.50.0 — CLI-hosted dashboard for desktop, presets re…
28d9505 
…moved, persisted usage stats, plan dispatch gate

Headline themes:
- Desktop: bundle the CLI-hosted React dashboard, retire Tauri+Preact duplicate (#1418)
- Config: drop preset abstraction; flash/pro are direct model selections (#1657, #1630)
- Stats: persist cumulative usage to session meta + auto-restore on startup (#1667, #1680, #1643, #1628)
- Plans: editMode="plan" enforced at the ToolRegistry dispatch gate (#1681); step advance fix (#1629)
- Context: fold once at turn start, drop pre-flight + byte-ceiling (#1642, #1646); collapsible compacted card (#1649)
- Subagents: per-skill flash/pro override + Settings UI (#1632)
- Desktop polish: sidebar drag-resize (#1688), responsive collapse (#1585), copy/edit overlay + msg-history nav (#1645), Esc closes modal not turn (#1685), QQ tab isolation (#1672), DiffCard for edits (#1662), theme-aware highlighting (#1655), system events toggle (#1654/#1650), macOS TCC inheritance (#1614), dashboard.enabled (#1612)
- Dashboard polish: persistent session URL (#1586, #1589, #1599), theme-aware highlighting (#1664), IME confirm-enter guard (#1689), code-fence lang fix (#1677), vendor chunk split (#1587), markdown table h-scroll (#1562)
- TUI: Alt+S input stash/recall; static history isolated from input rerenders (#1635); legacy mouse drop (#1637, #1648); multi-edit gated in review (#1647)
- Diff: SplitDiff column border holds under CJK (#1686)
- MCP: workspace roots passed to servers (#1625); codeCommand honors mcpServers (#1603)
- Config plumbing: (baseUrl, apiKey) resolved as a tuple (#1658); stale model id self-heal (#1663)

See CHANGELOG for the full list.
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@Bernardxu123 @esengine