Hermes Achievements Performance Implementation Plan

Status: Ready for execution after hackathon review window Constraint: Plugin remains frozen until judging is complete Decision: /overview and top-banner slots are out of scope and will be removed.

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Phase 0 — Baseline & Safety (no behavior change)

Task 0.1: Add perf benchmark script (local)

Objective: Repro baseline before/after.

Acceptance:

• Can print endpoint timings for /achievements (3 runs each, cold + warm).

Task 0.2: Define acceptance thresholds

Objective: Lock success criteria now.

Acceptance:

• Documented SLOs:
  • /achievements p95 < 1s (cached)
  • max active scan jobs = 1

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Phase 1 — Remove unused overview/slot surface (highest certainty)

Task 1.1: Remove /overview backend route

Objective: Eliminate duplicate heavy endpoint path.

Acceptance:

• plugin_api.py no longer exposes /overview.

Task 1.2: Remove slot registration and SummarySlot frontend code

Objective: Remove cross-tab banner fetch behavior.

Acceptance:

• No registerSlot(..."sessions:top"...) or registerSlot(..."analytics:top"...).
• No frontend call to api("/overview").

Task 1.3: Update plugin manifest

Objective: Reflect final UI scope.

Acceptance:

• manifest.json removes slots declarations.
• Tab registration remains intact.

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Phase 2 — Shared snapshot persistence + single-flight for /achievements

Task 2.1: Introduce snapshot store abstraction + on-disk persistence

Objective: Single source of truth for Achievements data that survives process restarts.

Acceptance:

• One structure contains dataset consumed by /achievements.
• Repeated requests do not recompute when cache is fresh.
• Snapshot persisted at ~/.hermes/plugins/hermes-achievements/scan_snapshot.json.

Task 2.2: Single-flight scan coordinator

Objective: Prevent concurrent recomputes.

Acceptance:

• Simultaneous requests result in one compute run.

Task 2.3: Refactor /achievements to read snapshot

Objective: Remove direct repeated compute from request path.

Acceptance:

• /achievements does not run independent full recompute per request when cache is valid.

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Phase 3 — Stale-While-Revalidate

Task 3.1: TTL state (FRESH/STALE)

Objective: Serve immediately when stale, refresh in background.

Acceptance:

• Cached response returned quickly even when expired.
• Refresh is asynchronous.

Task 3.2: Add scan-status endpoint (optional)

Objective: Let UI/ops inspect scan state.

Acceptance:

• Returns state, last success time, last duration, last error.

Task 3.3: Add metadata fields to /achievements

Objective: Improve transparency.

Acceptance:

• Response includes generated_at, is_stale, maybe scan_id.

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Phase 4 — Incremental Scanning (optional but recommended)

Task 4.1: Add per-session checkpoint file

Objective: Track session-level changes, not just global scan time.

Acceptance:

• Checkpoint persisted at ~/.hermes/plugins/hermes-achievements/scan_checkpoint.json.
• For each session: session_id, fingerprint (updated_at/message_count/hash), and cached contribution.

Task 4.2: Incremental aggregation

Objective: Recompute only changed/new sessions and reuse unchanged contributions.

Acceptance:

• Typical refresh time drops materially below full scan.
• Aggregate rebuild uses: subtract old contribution + add new contribution for changed sessions.

Task 4.3: Full rebuild fallback

Objective: Preserve correctness.

Acceptance:

• Manual full rescan always possible.
• Schema/version changes invalidate checkpoint and force full rebuild.

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Test Plan

1. Unit tests

• Snapshot lifecycle transitions
• Dedupe logic under parallel requests
• /achievements response compatibility

2. Integration tests

• Opening Achievements repeatedly causes <=1 heavy scan while in-flight
• /achievements warm-cache load is fast
• manual rescan updates snapshot and timestamps

3. Manual benchmarks

• Compare pre/post /achievements timings with same history dataset

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Rollout Plan

1. Release internal branch with Phase 1 (remove overview/slots).
2. Validate no UI regression in Achievements tab.
3. Add Phase 2 snapshot/dedupe.
4. Add Phase 3 stale-while-revalidate + status metadata.
5. Optional: incremental scanner.

Rollback: keep old compute path behind temporary feature flag for one release window.

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Definition of Done

• Achievements tab remains fully functional (counts, latest, tiers, cards, filters).
• No /overview endpoint or slot calls remain.
• Repeated Achievements loads feel immediate after warm cache.
• Metrics/unlocks remain unchanged versus baseline.