Update CLAUDE.md with eval 395 final results

568/643 succeeded (88.3%). Remaining 75 failures are from 3 root
causes: GCC fixincludes (32 windows), Determinate Nix orphaned store
paths (32 static-iog-full), hadrian stale cache (8 ghc910-static).
Confirmed the orphaned store path bug is reproducible across all
darwin builders and affects multiple multi-output packages.

Author: angerman

CLAUDE.md

@@ -70,21 +70,30 @@ pkgs.runCommand "devx" {} ''
 
 ### Latest Update (2026-02-15)
 
-**Eval 392** (commit 02e8a11): 566/643 succeeded, 75 dep-failed, 2 building.
-Root causes: postgresql-musl (orphaned store paths on builders), GCC-14.3.0 (infra),
-hadrian (stale cache).
-
-**Root cause discovery:** postgresql-musl builds SUCCEED on builders (all phases
-complete, output written to store), but outputs are NOT REGISTERED in the Nix
-database. This creates "orphaned store paths" — directories exist in /nix/store/
-but `nix path-info` says "path is not valid". The queue runner cannot copy
-unregistered outputs back to hydra, so the build is recorded as failed.
-
-This is a Determinate Nix bug on the darwin builders. Found 56 lock files on
-darwin-6, 869 on darwin-b — all indicating failed output registrations.
-Cleaned orphaned paths on all builders. Currently retrying builds.
-
-**Latest commit** 02e8a11 — clears disallowedReferences for postgresql musl cross.
+**Eval 395** (commit e80ee40): 568/643 succeeded, 75 failed, 0 building.
+This is a significant improvement from eval 370 (507 succeeded, 92 failed).
+
+**Root causes of remaining 75 failures:**
+- **32 windows builds**: GCC 14.3.0 `/usr/include` missing (infra fix needed)
+- **32 static-iog-full builds**: postgresql musl — Determinate Nix orphaned store paths
+- **8 ghc910-static builds**: hadrian — queue runner in-memory failure cache
+- **3 required builds**: aggregate failures from above
+
+**Determinate Nix orphaned store path bug (CONFIRMED REPRODUCIBLE):**
+postgresql-musl builds SUCCEED on builders (all phases complete, output written
+to store), but outputs are NOT REGISTERED in the Nix database. This creates
+"orphaned store paths" — directories exist in /nix/store/ but `nix path-info`
+says "path is not valid". The queue runner cannot copy unregistered outputs
+back to hydra, so the build is recorded as failed. This bug reproduces on
+every retry across all darwin builders and both musl architectures. It also
+affects other multi-output packages (aeson, pretty-show, ghc-lib-parser, HLS).
+
+**Queue runner failure cache**: The queue runner maintains an in-memory cache
+of failed derivations that persists across restarts and survives deletion of
+buildstep entries and build logs. The only way to bypass it is to change the
+drv hash (e.g., adding a cache-breaking attribute to the derivation).
+
+**Latest commit** e80ee40 — cache breaker for postgresql musl (preBuild no-op).
 
 **Summary of all fixes applied (in overlay order):**
 1. **happy disallowGhcReference** (build-fixes): Disable GHC reference check for