# Pi Embedded Canary Evaluation (Phase 2)

Status: in progress  
Owner: Flynn maintainers  
Started: 2026-02-24

## Goal

Close the canary spike with a formal, repeatable evaluation and an explicit rollout decision (`expand`, `hold`, or `rollback`).

## Scope

- Target backend: `pi_embedded`
- Target cohort (current): `telegram:8367012007`
- Baseline backend: `native`
- Data source: audit events (`backend.route`, `backend.success`, `backend.fallback`, `session.message`)

## Pass/Fail Gate

Use the same thresholds for every evaluation window.

| Metric | Gate |
| --- | --- |
| Completion rate delta (target - baseline) | >= -2.00pp |
| P50 latency delta (target - baseline) | <= +250ms |
| P95 latency delta (target - baseline) | <= +700ms |
| External fallback rate (`pi_embedded`) | <= 5.00% |
| Guardrail escapes | 0 unresolved |

Notes:
- Completion rate and latency are computed from route-to-assistant turn timings.
- Fallback rate is computed from `backend.success` + `backend.fallback` attempt outcomes.
- Guardrail escapes are reviewed from `backend.route.source == forced_native_guard` + operator incident review.

## How To Run

Run a canary summary for the current cohort:

```bash
pnpm audit:backend-canary \
  --audit ~/.local/share/flynn/audit.log \
  --backend pi_embedded \
  --baseline native \
  --session telegram:8367012007 \
  --format markdown
```

Run with gate evaluation and emit JSON artifact:

```bash
pnpm audit:backend-canary \
  --audit ~/.local/share/flynn/audit.log \
  --backend pi_embedded \
  --baseline native \
  --session telegram:8367012007 \
  --format json \
  --out docs/plans/artifacts/pi_embedded_eval_latest.json \
  --gate-max-completion-drop-pp 2 \
  --gate-max-p50-latency-increase-ms 250 \
  --gate-max-p95-latency-increase-ms 700 \
  --gate-max-fallback-rate-pct 5
```

## Evaluation Log

### Window A

- Dates: _TBD_
- Route volume: _TBD_
- Summary artifact: _TBD_

| Check | Result | Notes |
| --- | --- | --- |
| Completion rate delta | _TBD_ | |
| P50 latency delta | _TBD_ | |
| P95 latency delta | _TBD_ | |
| Fallback rate | _TBD_ | |
| Guardrail escapes | _TBD_ | |

### Window B

- Dates: _TBD_
- Route volume: _TBD_
- Summary artifact: _TBD_

| Check | Result | Notes |
| --- | --- | --- |
| Completion rate delta | _TBD_ | |
| P50 latency delta | _TBD_ | |
| P95 latency delta | _TBD_ | |
| Fallback rate | _TBD_ | |
| Guardrail escapes | _TBD_ | |

## Tool Compatibility Findings

Track all tool-adjacent/risky prompts that were force-routed to native (`no_tools_mode`) and any misses.

| Class | Observed behavior | Action |
| --- | --- | --- |
| Tool-adjacent prompts | _TBD_ | |
| Capability-query prompts | _TBD_ | |
| Attachments-present turns | _TBD_ | |

## Decision Record

- Decision date: _TBD_
- Decision: _expand | hold | rollback_
- Rationale: _TBD_
- Next cohort/config delta: _TBD_

## Diagram/Protocol Impact Review

- Reviewed: `docs/architecture/AGENT_DIAGRAM.md`, `docs/architecture/GATEWAY_SESSIONS_AND_QUEUE.md`, `docs/api/PROTOCOL.md`
- Result: no runtime message-flow or protocol-shape changes; no Mermaid topology update required for this evaluation-tooling phase.