Branch switches invalidate and eagerly resend full Git history over SSH, delaying protocol responses and potentially contending with terminal traffic

Reproduction steps

1. On the SSH host, clone FreeBSD with its full main-branch history:

   bash复制

   git clone --single-branch --no-tags --branch main https://github.com/freebsd/freebsd-src.git
   cd freebsd-src
   git switch --create repro-base 04fcf30961266cd77139b40774cb0d6ef6eb2be5
   git branch repro-next f6db138f97b78e641b07a7c3695ccf62b0f42f28

2. Open the repository over SSH in Zed. Wait for initial loading to finish, then open the integrated terminal.

3. Switch to repro-next using Zed’s branch picker. Type in the terminal and try opening a file.

4. After responsiveness returns, switch back to repro-base and repeat.

The branches differ by one commit, one file, and one added line. The test repository had approximately 313,000 commits.

Current vs. Expected behavior

Expected: Switching between branches that differ by one line leaves integrated terminal typing and file opening responsive.

Current: Both become sluggish after the switch, then recover. This reproduced in both directions on FreeBSD using Zed 1.20.2 with fresh Mac configuration/data and isolated remote Zed state.

Why I suspect history transfer:

The public FreeBSD test used original release binaries without protocol interception:

Both captures cover 10 seconds before the observed HEAD change through 60 seconds after. Blocked writes continued after the sampled Git history process disappeared. These byte counts include all proxy writes, not specifically history messages or exact network traffic.

An earlier test on Zed 1.19.2 with a private repository identified the bulk messages as GetInitialGraphDataResponse. We compared the same branch switch with a diagnostic wrapper forwarding everything versus removing only history response bodies while preserving protocol bookkeeping:

The run with history bodies removed did not lag. Source inspection of that version showed that branch changes clear the history cache and the Git panel preloads the full history even outside the History tab. The measured for-each-ref operation ended before the long transfer.

Together, these results point to history transfer as a contributor. The terminal shares the SSH connection with Zed’s protocol, so transport contention could explain delayed echo. Direct typing latency was not measured, and the public test’s payload types were not decoded.

Zed version and system specs

Zed: v1.20.2+stable.360.7c451e694f3c52ee0aeb01d7e28b5fa18cd0ad2f (Zed) OS: macOS 26.6.2 Memory: 36 GiB Architecture: aarch64

Remote host: Ubuntu 22.04, x86_64. Remote server used in the trial: 1.19.2+stable.356.df181c6f58d02677b385fa947d6bfde6d3530078.

Attach Zed log file

Zed log contains no relevant entries during the reproduction

Relevant Zed settings

Relevant Keymap

(for AI issues) Model provider details

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If you are using WSL on Windows, what flavor of Linux are you using?

None