mcp: session-notes — petal-dispatch v3 — Phase −1 measured deltas

Sources/Dev/2026-06-04-2026-06-04-petal-dispatch-v3-phase-minus-1-deltas.md

@@ -0,0 +1,35 @@
+---
+created: '2026-06-04'
+path: Sources/Dev
+project: petal-dispatch-v3
+tags:
+- petal-dispatch
+- v3
+- phase-minus-1
+- oauth
+- journal
+- lovebug
+- claude-code
+- errata
+type: session-notes
+---
+
+Phase −1 of the v3 build ran the OAuth viability spike on 2026-06-04 and surfaced findings that materially patch the v3 spec. v3 is immutable; this note is the consumption layer for future readers.
+
+Full results live in trellis thread `petal-dispatch-v3-build` (id 588), checkpoint event 1084. Raw artifacts in repo `petal-power/petal-dispatch` (currently `petal-dispatch-demo`) under `phase-minus-1/`.
+
+## Corrections to v3
+
+**D-11 (OS exit code mapping): drop the SIGINT/130 row.** Measurement: claude under stream-json treats SIGINT-when-busy as a clean exit; rc=130 is unreachable. The orchestrator's cancel path is SIGTERM (rc=143 → `cancelled`), the crash path is SIGKILL (rc=137 → `crashed`). SIGINT plays no role in v1. The rest of the v3 mapping (0 → success, nonzero → failed, 143 → cancelled, 137 → crashed) holds; the SIGINT row was conjectural.
+
+## Additions to internalize when reading v3
+
+**Init event exposes `mcp_servers[*].status` (per-spawn).** D-21 plumbing: the harness can detect `needs-auth` MCPs at spawn time and route around them instead of crashing on an interactive prompt. The Phase 0 event taxonomy should treat MCP-status as a first-class signal in init events.
+
+**`system init` fires per user_message in long-lived stream-json mode.** Not a one-time event. The orchestrator state machine and the journal's event-type reference table must accept >1 `init` event per process lifetime. Relevant to Phase 0 and any forward-compat planning for long-lived workers (v4 lifecycle).
+
+**`rate_limit_event` is a status-only signal.** Payload reports `status` (allowed / not) with no remaining-quota gauge. Phase 2's not-clean-return policy for `rate_limited` (FR-009 / D-18 / Phase 2) must back off on `status != allowed` rather than on a quota threshold. Forecasting headroom from this signal is not possible; the orchestrator only sees the binary circuit-breaker state.
+
+## What did NOT change
+
+D-21 (extractor as Claude Code spawn), D-13 (two-service split), Phase −1's OAuth decision, and the harness-as-sole-substrate-touching-layer containment argument all hold under measurement. Six of seven Phase −1 tests passed cleanly; the one PARTIAL was the SIGINT row above.