Usage 0.29.20

**Saving a setting turned a symlinked config file into a regular one.** Every settings write goes through `_atomic_write_text()`, which writes a temporary file and then `os.replace()`s it over the target — the standard way to make sure a crash mid-write cannot leave half a file behind. `os.replace()` does not follow symlinks, though, so for anyone who manages `~/.claude/settings.json` or `~/.codex/config.toml` from a dotfiles repository, the symlink was silently replaced by a plain file: the repository copy stopped receiving updates, nothing warned, and the divergence only showed up the next time those dotfiles were deployed somewhere else. The target is now resolved to its real path before the replace, and the temporary file is created next to that real path rather than next to the link — putting it beside the link would move the rename across filesystems, which fails outright with `Invalid cross-device link` and would have traded one silent breakage for a louder one. The atomic write itself is unchanged. `statusline_settings.py` had grown its own copy of this sequence and now calls the shared helper, so `settings.json`, `config.toml` and `hooks.json` are all covered by one implementation.

**The self-heal log could discard settings Claude Code had just written.** `_append_self_heal_log()` reads `settings.json`, appends an entry and writes the whole file back. Claude Code writes the same file, and anything it stored between that read and that write — a newly granted `permissions.allow` entry, for instance — was overwritten by the older copy still held in memory. The window is milliseconds wide, which is exactly why it would have been diagnosed as a mystery rather than as a race. The read-modify-write is now held under a `flock`, reusing the lock helper the status line already uses. It takes its own `usage-settings.lock` rather than sharing the status line's `usage-status.lock`: that one guards a different file written on every message, and sharing it would serialise two unrelated things for no benefit.

**A short secret redacted every occurrence of its characters.** `_redact_environment_values()` masks sensitive environment values out of transcripts by substring replacement. Nothing bounded how short a value could be, so an environment variable matching the sensitive-name pattern whose value happened to be `1` turned every `1` in the message into `[REDACTED]` — timestamps, token counts, error codes. Values shorter than eight characters are now skipped; a secret that short is not one worth protecting, and treating it as one destroys the surrounding text.

**The vendored instate CLI was bundled and executed without being verified.** `scripts/build_app.sh` downloads the binary from a release when the local `instate` project is not present, then packages it into the `.app` as-is. There was nothing to detect a substituted or corrupted download. The build now pins the expected SHA-256 in `scripts/instate-cli.sha256` and refuses to continue when the downloaded binary does not match, deleting it rather than leaving a suspect file behind for the next run to reuse. The fingerprint is committed to this repository rather than published beside the release asset on purpose: a checksum stored next to the binary can be rewritten by whoever rewrites the binary, which verifies nothing. A download that fails outright still logs a warning and continues — that is a missing panel, not a compromised one.

**Three passages of duplicated code were extracted.** The sharded disk caches for Claude and Codex history held sixty-three identical lines, and `codex_disk_cache.py` reached across to import `history_disk_cache.py`'s private serialisers and re-export them under its own `__all__` — a detour that made the real owner of that code impossible to see. Serialisation, shard paths and index, stale-cache removal and the payload read/write now live in `disk_cache_common.py`. The disk-cache lifecycle shared verbatim by all three loaders — the one-time seed check, the throttled flush and the best-effort flush on termination — moved to `disk_cache_lifecycle.py`. The loaders themselves are still three separate modules and stay that way; they parse three unrelated formats, and only the cache plumbing around them was ever the same. In `session_hooks.py`, three pairs of `_is_X_entry`/`_strip_X_hooks` differing only in a marker constant were parameterised, with the six original names kept as thin wrappers. `agy_disk_cache.py` was deliberately left out: it is a single JSON file with no sharding, and forcing it into the shared shape would have meant changing its behaviour to fit. Net 218 lines removed, with no behavioural change.
**Dead constants, two unused functions and thirteen orphaned translation keys were removed.** The keys came from renames and from the AI-updates feature moving to its own repository. Finding them took more care than the count suggests: a plain text search over the source reported 159 orphans, of which 146 were false. Keys are frequently assembled at runtime rather than written out — `discussion.html` builds `discussion_status_round1_running` by lowercasing a `SessionStatus` value, and `ui/html_report.py` prepends `report_` to every key it looks up, so four live `report_wrapped_beast_*` entries appear nowhere in the source under their full names. `agy_loader.recent_input_output_tokens()` looks equally dead from inside this repository and was kept: its only caller is a script outside it.