{"record":{"id":"c219fe3598b5ca43","repo":"GitoxideLabs/gitoxide","slug":"the-head-pin-changed-while-preparing-to-attach","errorCode":null,"errorMessage":"the HEAD pin changed while preparing to attach","messagePattern":"the HEAD pin changed while preparing to attach","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"gix-tix/src/edit/time_travel.rs","lineNumber":517,"sourceCode":"    }\n    Ok(RememberedBranch {\n        branch,\n        branch_tip: pin.id,\n    })\n}\n\nfn validate_attach(repository: &gix::Repository, head_id: ObjectId, remembered: &RememberedBranch) -> Result<()> {\n    let head = repository.head().context(\"could not read HEAD before attaching\")?;\n    if !head.is_detached() || head.id().map(gix::Id::detach) != Some(head_id) {\n        anyhow::bail!(\"HEAD changed while preparing to attach\");\n    }\n    drop(head);\n    let pin = history::all_pins(repository)?\n        .into_iter()\n        .find(history::Pin::is_head)\n        .context(\"the HEAD pin disappeared while preparing to attach\")?;\n    if pin.target.try_name() != Some(remembered.branch.as_ref()) || pin.id != remembered.branch_tip {\n        anyhow::bail!(\"the HEAD pin changed while preparing to attach\");\n    }\n    let branch_id = repository\n        .find_reference(remembered.branch.as_ref())\n        .context(\"the remembered branch disappeared while preparing to attach\")?\n        .try_id()\n        .context(\"the remembered branch must be a direct reference\")?\n        .detach();\n    if branch_id != remembered.branch_tip {\n        anyhow::bail!(\"the remembered branch changed while preparing to attach\");\n    }\n    ensure_branch_is_available(repository, remembered.branch.as_ref())\n}\n\n#[cfg(test)]\npub(crate) fn attach(\n    repository_path: &Path,\n    bare: bool,\n    revisions: &[OsString],","sourceCodeStart":499,"sourceCodeEnd":535,"githubUrl":"https://github.com/GitoxideLabs/gitoxide/blob/e73179060badf27222d790981fac3f84c1830a7e/gix-tix/src/edit/time_travel.rs#L499-L535","documentation":"The HEAD pin discovered during `validate_attach` differs from what was remembered: its symbolic target no longer equals the remembered branch name or its commit id differs from the remembered tip. The library bails rather than attach to a branch state that drifted mid-operation. This is a second staleness guard after the HEAD-id check.","triggerScenarios":"In attach_reporting/validate_attach: after remembering the branch, the HEAD pin's target name or pin id changed (e.g. a commit was added to the branch, or HEAD was re-pointed to another branch) before validation.","commonSituations":"Concurrent commits by another tool; an editor auto-fetch/checkout; a background job advancing the branch while the attach was being prepared.","solutions":["Retry the attach when the repository is quiescent.","Identify and stop the concurrent process modifying the branch/HEAD.","Re-capture the remembered branch by restarting the flow so the snapshot matches current state."],"exampleFix":null,"handlingStrategy":"retry","validationCode":null,"typeGuard":null,"tryCatchPattern":"match attach_reporting(...) {\n    Err(e) if e.to_string().contains(\"HEAD pin changed while preparing\") => {\n        // restart the whole flow so the remembered snapshot is fresh\n        restart_attach_flow()?;\n    }\n    other => other?,\n}","preventionTips":["Serialize all writers to the repository during the flow.","Re-run the flow promptly after remembering; long gaps invite races.","Check `git reflog` for concurrent movements when diagnosing."],"tags":["git","race-condition","concurrency","pin-changed"],"backgroundTag":"invalid-state-transition","analyzedSha":"e73179060badf27222d790981fac3f84c1830a7e","analyzedAt":"2026-09-08T11:26:50.865Z","contentChangedAt":"2026-09-08T11:26:50.865Z","schemaVersion":2},"datasetVersion":"2026-09-15T23:17:13.987Z"}