diff --git a/plugins/ultraplan-local/CLAUDE.md b/plugins/ultraplan-local/CLAUDE.md
index 78e96b6..653c74e 100644
--- a/plugins/ultraplan-local/CLAUDE.md
+++ b/plugins/ultraplan-local/CLAUDE.md
@@ -157,15 +157,15 @@ All four pipeline commands accept `--gates {open|closed|adaptive}`:
 
 Under the hood: `lib/util/autonomy-gate.mjs` runs the state machine `idle → approved → executing → merge-pending → main-merged`. `lib/stats/event-emit.mjs` records each transition to `${CLAUDE_PLUGIN_DATA}/ultra*-stats.jsonl`. The main-merge gate is the final autonomy boundary before HEAD lands on `main`.
 
-### Path A/B/C decision (v3.4.0)
+### Path A/B/C decision (v3.4.0; Path C closed 2026-05-05)
 
 Three architectural options were considered for the speedup work:
 
 - **Path A — cache-first** (drop `--allowedTools` per child to recover cross-phase cache sharing): REJECTED. Inverts the security model; plugin hooks don't fire reliably in `claude -p` (research/06 GH #36071).
 - **Path B — sequential `--no-ff` parallel waves with manifest-driven failure recovery**: CHOSEN. Ships in v3.4.0. Phase 2.6 of `/ultraexecute-local` runs the wave executor with hardenings for plugin-in-monorepo + gitignored-state topology.
-- **Path C — hybrid (cache-warm sentinel + identical-tool parallel)**: DEFERRED to v3.5.0 contingent on cache-telemetry data harvested by `lib/stats/event-emit.mjs`. Path C requires unverified Q3 (CLAUDE_CODE_FORK_SUBAGENT cache-prefix preservation at 150-250K context).
+- **Path C — hybrid (cache-warm sentinel + identical-tool parallel)**: **CLOSED 2026-05-05.** Q3 experiment measured median `cache_creation_input_tokens` = 163,903 across 3 fork-children at 186K parent context (CC v2.1.128, Sonnet 4.6). Master-plan thresholds: ≤ 1,500 POSITIVE / ≥ 3,500 NEGATIVE. Result is solidly NEGATIVE — `CLAUDE_CODE_FORK_SUBAGENT` does not preserve cache prefix across identical-tool children at our context size. Path C migration is deferred indefinitely; reassessment is appropriate when CC v2.2.xxx ships fork-cache-relevant features. Harness: `scripts/q3-cache-prefix-experiment.mjs`. Companion analyser: `lib/stats/cache-analyzer.mjs`.
 
-Path C migration would require: (1) re-architecting tool-list to be identical across all wave children, (2) cache-telemetry analysis confirming Q3 holds, (3) prompt-level deny re-enablement to compensate for tool scoping rollback.
+A revived Path C (post-v2.2.xxx) would require: (1) re-architecting tool-list to be identical across all wave children, (2) cache-telemetry analysis confirming the new fork-cache behaviour holds, (3) prompt-level deny re-enablement to compensate for tool scoping rollback.
 
 ## Architecture