Support sandbox session lookup after commits on detached HEAD#414
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Support sandbox session lookup after commits on detached HEAD#414
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Adds git merge-base --is-ancestor support, which will be used for ancestry-based sandbox session lookup on detached HEADs.
When a detached HEAD advances (e.g. Codex making commits in a worktree), the session key no longer matches. GetSessionByAncestry and GetSessionsForCwdBranchByAncestry fall back to git ancestor checks, and re-key matching sessions to the current SHA to avoid repeated misses.
When on a detached HEAD and an exact session lookup misses, fall back to ancestry-based matching. This handles the case where tools like Codex commit on a detached HEAD, advancing the SHA while the sandbox is still running. Applied to CheckExistingSandbox, ExecSandbox (both specific-config and no-config paths, plus remote recovery), StopSandbox, and ResetSandbox.
kylekthompson
approved these changes
Mar 11, 2026
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Summary
detached@<short-sha>, so the CLI could no longer find the running sandbox.IsAncestorto the git client, wrappinggit merge-base --is-ancestor.GetSessionByAncestryandGetSessionsForCwdBranchByAncestrytoSandboxStorage, which fall back to ancestry-based lookup when an exact key match fails on a detached HEAD. Matching sessions are re-keyed to the current SHA to avoid repeated misses.CheckExistingSandbox,ExecSandbox(specific-config, no-config, and remote recovery paths),StopSandbox, andResetSandbox.Test plan
IsAncestor(ancestor, descendant, unrelated, equal, non-repo)GetSessionByAncestry(match + re-key, no match, wrong cwd/config, named branch, bare detached)GetSessionsForCwdBranchByAncestry(multi-config match, non-ancestor filtered, empty)./internal/cli/and./internal/git/test suites passrwx sandbox execandrwx sandbox stopstill find the sandbox