deferred(2): Q4.7 plausible — drafted but 500 on cold-start, defer for operator-iterate

tests/plausible/recipe_meta.py + tests/plausible/functional/test_health_check.py drafted with
EXTRA_ENV setting required Phoenix vars (DISABLE_AUTH, DISABLE_REGISTRATION, SECRET_KEY_BASE).
Stack converges 1/1 but the served app returns HTTP 500 from / for the full 600s HTTP_TIMEOUT
window — config-class failure, not a deploy-timing issue. Diagnosing needs live container-log
inspection + iterative env tuning, more debug cycles than fit autonomous mode. Committing the
draft + a DEFERRED.md entry; operator can iterate when they want.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

machine-docs/DEFERRED.md

@@ -168,3 +168,20 @@ before the build is called done) — but does **not** force closure.
 
 ## Closed deferrals
 (none yet — append `### YYYY-MM-DD — <slug> CLOSED (commit/PR)` here when re-entered.)
+
+### 2026-05-28 — plausible (Q4.7) recipe enrollment
+- [ ] **What:** Enroll plausible in cc-ci with parity health_check + ≥2 specific tests (per
+      plan §4.3: "track a test event, query it back"). `tests/plausible/recipe_meta.py` +
+      `tests/plausible/functional/test_health_check.py` are drafted (commit pending) but the
+      e2e fails: services converge but the served app returns HTTP 500 from `/` for the full
+      600s HTTP_TIMEOUT window — config-class failure, not a deploy-timing issue.
+- **Filed by:** Builder, phase 2
+- **Reason for deferral:** The first deploy attempt set EXTRA_ENV={DISABLE_AUTH=true,
+  DISABLE_REGISTRATION=true, SECRET_KEY_BASE=<64-char fixed>}. Stack converged 1/1 but the
+  Phoenix app returned 500 the whole window. Likely missing required config (e.g. DATABASE_URL,
+  MAILER vars, or a Phoenix bootstrap step). Diagnosing requires live container-log inspection
+  + iterative env tuning — more debug time than fits a single autonomous loop pass.
+- **Operator action to lift:** Either (a) iterate on plausible's required env / debug live
+  logs in an interactive session; OR (b) re-enroll plausible after the operator confirms a
+  working env recipe.
+- **Linked IDEA:** —