# ACP Registry binary version proof

Environment: real web client in Chromium, light theme, 1280 × 800 CSS viewport (2× capture scale), separate development servers and fresh isolated T3 homes for each commit, T3CODE_DEV_SEED=0. No production database was used. No app code was changed.

Base: f7b81e1d1115bc7284b39161d3cd6c7f3184eb1c
Head: ed562dd324cc6f2b9876577827aa091f4e4b3c4b

## Same setup on each commit

1. Install dependencies with `vp i`, then start with `T3CODE_DEV_SEED=0 vp run dev`.
2. Pair a browser using its startup pairing URL. Open Settings → Providers → Add provider → Show more → ACP Registry → Devin → Add. Continue through Identity and Skip for now on sign-in. The real 3000.12.43 release downloads and becomes Available.
3. Stop the development server. Fetch the official registry JSON and the real older binary archive:
   - https://cdn.agentclientprotocol.com/registry/v1/latest/registry.json
   - https://static.devin.ai/cli/3000.12.42/devin-3000.12.42-x86_64-unknown-linux.tar.gz
4. Run `python3 registry-state.py T3_HOME registry.json devin-old.tar.gz SAVED_CURRENT_DIR older`. This retains the existing provider instance, moves the current install out of the home, extracts the actual older binary into its normal managed path, and changes the cached Devin entry to 3000.12.42 with its real archive URLs.
5. Restart, open Providers, select Devin. Confirm 3000.12.42 is Available on both commits. Capture the initial state.

## Reproduction on each commit

1. Stop the server. Run the same driver with the final argument `advance`. It changes the cached registry back to the official 3000.12.43 entry while leaving only 3000.12.42 installed.
2. Record the browser while restarting the same server. Open Providers and select the existing Devin instance.
3. Base shows Not found and "ACP Registry agent 'devin' has not been prepared on this environment." Head shows Available.
4. Close Settings, open a new draft's model picker and search for Devin. Base says No models found; head offers Default under Devin. Click Default on head; the picker closes and the composer switches to Default.
5. Inspect managed install versions. Base retains only 3000.12.42. Head has both versions, and executing the newly downloaded binary with `--version` reports `devin 3000.12.43 (517d03d73926)`.

## Evidence processing

Stills were captured twice at least 500 ms apart and their cropped pixel regions compared equal (0 differing pixels). Each uploaded image was opened and inspected. Images are cropped to the provider details or filtered picker to exclude unrelated private information. Videos show the same provider-selection interaction after restart, cropped to the same provider details region; 25 seconds are retained from each recording. Video frames were inspected on contact sheets. No status text or model results were altered.

Authenticated Devin turns were not run; no native Devin account credentials were available. The real binary download, background probe, Available status, and model selection were verified without sign-in.

AI-assisted; verified with the tests and tools listed above.