---
name: shared-seam-change-run-all-seam-tests
description: "Gating lesson: a behavior change to a SHARED runtime seam can break SIBLING tests that exercise it — targeted preflight on only the new tests misses them. Grep + run ALL tests touching the seam before declaring green."
metadata: 
  node_type: memory
  type: feedback
  originSessionId: 8350d43e-fe2d-4e24-9999-eecbcc6d3a50
---

When a change alters a SHARED runtime seam, the new/changed tests passing is NOT enough — a SIBLING test exercising the same seam with a different fixture can silently break, and a targeted preflight (only the new tests + the obviously-related E2Es) won't catch it. CI runs the FULL suite and will.

**Why:** v0.8.2 F-010 added a Psyche residency check inside the daemon's continuous reconcile (`confirm_residency_or_unhost`). The new E2Es (bootrace/nonresident) were green, but a SIBLING — `spt-daemon/tests/daemon_lifecycle_real_brain.rs` — ran the SAME continuous `run_brain` reconcile with a NOOP **fast-exit** psyche (`cmd /C rem`/`true`), which post-change is now a *Failed* host → pulse driver torn down → its commune-ingest assert timed out. Targeted preflight ran the livehost E2Es but not that spt-daemon sibling → CI caught it (1 failed/1112, Windows; Linux won the race). Cost: a full gate round-trip + re-gate.

**How to apply:** before declaring a seam-touching change green —
1. `grep` for ALL tests that exercise the seam, not just the ones you wrote. For a daemon-reconcile/psyche change: `run_brain(` · `spawn_live_host` · real `daemon run` · `psyche_init` fixtures. For a template/spawn change: the spawn callers. For a wire/schema change: every encoder/decoder test.
2. Run that whole set locally (or the full crate suite if bounded) — not only the new tests.
3. Watch for fixtures that were innocuous before but now hit the new code path (e.g. a fast-exit/NOOP fixture under a new residency/liveness rule).

Test-analog of [[ci-clippy-preflight-workspace]] (a `-p <crate>` clippy misses sibling-crate lints; a targeted test run misses sibling-seam tests). Same fix posture: pre-flight the BROAD surface the change actually touches. See [[v082-templating-residency]] for the concrete case.