Fix stale eval-cache invalidation for devenv up process config changes#2632
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domenkozar merged 1 commit intoMar 18, 2026
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…uation entirely. It is reusing the cached build result for devenv.config.procfileScript from devenv/src/devenv.rs
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Mar 18, 2026
Verifies that dropping one ObserverClearGuard does not remove another evaluation's observer from the shared NixLogBridge. Also adds changelog entry for the fix. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Added a test and changelog in 44ff299, thank you! |
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DISCLAIMER: Both bug triage, fix and this summary is AI Generated (Codex 5.4).
(However, a human experienced the bug and validated the fix.)
This fixes a cache invalidation bug that could cause devenv up to keep using an old processes configuration even after devenv.nix changed.
In the failing case, devenv up would still rebuild the procfile-related attribute path, but the evaluation could hit a stale cached result because not all file dependencies from nested evaluations were preserved. The visible symptom was that changes under processes were not reflected unless the user manually forced --refresh-eval-cache.
Root Cause
The eval-cache layer registers an observer to collect file and environment inputs during cache misses. That observer is used to determine when a cached evaluation should be invalidated.
On drop, the observer guard called clear_observers(), which removed every active observer from NixLogBridge, not just the collector created for that specific evaluation. In nested or overlapping evaluation paths, this could accidentally remove other collectors that were still needed.
As a result, some cached entries could be stored with incomplete dependency sets. When devenv.nix or related imported files later changed, those cache entries could still validate as fresh and return stale results.
Fix
The observer guard now removes only the observer it owns, using remove_observer(...), instead of clearing the full observer list.
This keeps dependency collection isolated per evaluation and preserves the complete input set needed for correct eval-cache invalidation.
User Impact
Before this change:
After this change: