[yaacovcorcos]

Problem

prepareCommitContext stages with a temporary index, but git add -A still writes every staged
blob into the repository's object store. When no commit follows (message generation fails or is
stopped), those blobs stay as unreachable loose objects until gc prunes them; with large generated
files or datasets that is their compressed size, close to the file size for data that does not
compress, and later maintenance has to process it. Details: #34594.

Change

Preparation also sets GIT_OBJECT_DIRECTORY to an objects folder inside its existing temporary
directory, so new blobs go there and are removed with the temporary index. Everything the
repository can already read stays readable: GIT_ALTERNATE_OBJECT_DIRECTORIES lists the
repository's object directory (git rev-parse --git-path objects, so a linked worktree uses the
common directory) followed by every alternate git count-objects -v reports for it. Listing them
directly keeps alternates that come only from the environment, and keeps a long chain of shared
clones within Git's alternate nesting limit (an extra level would push a six-deep chain past it).
Entries are C-quoted as Git prints them (supported since Git 2.11.1), so a path containing the list
separator stays one entry. The commit itself is unchanged and stages into the real index and object
store as before.

Trade-off: a commit that follows preparation now compresses its newly prepared blobs a second time,
because the prepared copies were in the temporary folder (before, it found them already written).
This applies to every commit through this path, including ones with a message the user wrote, since
preparation runs for those too (without a patch). count-objects -v also adds one command that
scans the loose-object folders.

Scope and approval

Fixes #34594. A focused fix of an obvious bug in one function (the temporary index already shows the
intent: preparation must not change the repository), with no setting, contract, or UI change.
Submitted under the focused obvious-bug exception in CONTRIBUTING.md; no maintainer approval is
claimed.

Verification

New tests in GitVcsDriverCore.test.ts:

• leaves no objects behind when no commit follows, in a linked worktree too: in a repository and
  in a linked worktree it changes a tracked file and adds an untracked one, prepares the context,
  checks the patch, and checks with git cat-file -e that neither blob is in the repository. It
  fails on main (the blob is present) and passes with the change.
• reads history through environment alternates and a chain of shared clones: a six-deep
  git clone --shared chain and a borrower whose alternate is set only in the environment both
  still report the edit as a modification. It fails if only the repository's own object directory
  is listed.
  The commit context tests pass (vp test run src/vcs/GitVcsDriverCore.test.ts -t "commit context",
  macOS, Apple Git). Server typecheck, vp lint and vp fmt on apps/server/src/vcs. Not run on
  Linux or Windows.

Written with Claude Opus 5.5 in Claude Code; reviewed with gpt-6.1-sol in Codex.

[chatgpt-codex-connector]

Codex Review Summary: ✅ Completed

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-11T22:21:40.503033Z	738afcd	PR opened

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[macroscopeapp]

Approvability

Verdict: Approved at 738afcd

Macroscope's review found this PR approvable — Commit-message preparation now stores newly staged objects in temporary storage rather than leaving them in the repository. The change is confined to preparation, with scoped cleanup and no change to actual commits.

^{You can add or adjust custom eligibility rules. Learn more.}

[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

prepareCommitContext now stages changes in a temporary object directory while configuring Git to read the repository object directory and discovered alternates. Tests check commit-context contents across chained shared clones, repositories, and linked worktrees, and verify that draft blob objects do not remain in the repository.

Changes: Commit context object storage

Layer / File(s)	Summary
Configure temporary object storage and verify commit context apps/server/src/vcs/GitVcsDriverCore.ts, apps/server/src/vcs/GitVcsDriverCore.test.ts	prepareCommitContext configures a temporary object directory and sets repository and discovered alternate object directories as alternates. Tests check changes through six successive shared clones and verify modified and untracked content for a repository and linked worktree without leaving the blobs in the repository.

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Low

Suggested reviewers: juliusmarminge, t3dotgg, saphid

Merge Risk: Minimal · up to 10d10

Commit-message preparation no longer leaves unreachable objects in the repository. The author tested on macOS only, so Linux and Windows behavior was not exercised, but the change does not show a concrete merge-blocking risk.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title names the main change: preparing commit context no longer writes git objects into the repository. It follows the conventional commit format and matches the raw summary, the linked issue #345…
Description check		The description follows the template. It has Problem, Change, Scope and approval, and Verification sections. The Problem section explains the blob leak and links #34594. The Change section explains th…
Linked Issues check		Issue #34594 requires that preparing commit context leave the repository unchanged when no commit follows. In apps/server/src/vcs/GitVcsDriverCore.ts, prepareCommitContext now sets GIT_OBJECT_DIRECTOR…
Out of Scope Changes check		The source diff changes only prepareCommitContext in GitVcsDriverCore.ts. The added rev-parse objects path, count-objects -v call, alternate listing, C-quoting, and temporary objects directory all ser…

Full details: Title check

Explanation

The title names the main change: preparing commit context no longer writes git objects into the repository. It follows the conventional commit format and matches the raw summary, the linked issue #34594, and the objectives. It is concise and specific.

Full details: Description check

Explanation

The description follows the template. It has Problem, Change, Scope and approval, and Verification sections. The Problem section explains the blob leak and links #34594. The Change section explains the temporary object directory, the alternates handling, and the trade-offs. The Scope section cites the focused obvious-bug exception and states that no maintainer approval is claimed. The Verification section lists the new tests, the commands run, the macOS-only testing, and the lack of Linux and Windows runs. It also names the model and harness used, as the template asks. The Scope section cites CONTRIBUTING.md and does not show the exception text, so a reviewer should confirm that the exception applies.

Full details: Linked Issues check

Explanation

Issue #34594 requires that preparing commit context leave the repository unchanged when no commit follows. In apps/server/src/vcs/GitVcsDriverCore.ts, prepareCommitContext now sets GIT_OBJECT_DIRECTORY to an objects folder inside the temporary directory. Blobs written by git add -A therefore go to that folder. The folder is removed with the temporary index when the scope closes. The env also sets GIT_ALTERNATE_OBJECT_DIRECTORIES to the repository object directory (from git rev-parse --git-path objects, resolved against cwd) followed by each alternate line from git count-objects -v. This keeps existing objects readable. Alternates are C-quoted, so entries containing the separator stay single entries. The separator is ';' on Windows and ':' elsewhere. The commit path is not changed by this diff, so it still stages into the real index and object store. The new test 'leaves no objects behind when no commit follows, in a linked worktree too' is described as checking with git cat-file -e that prepared blobs are absent. I did not read the test file or run the tests. The source evidence supports the fix. The Windows path and the Linux behavior were not verified by the author.

Full details: Out of Scope Changes check

Explanation

The source diff changes only prepareCommitContext in GitVcsDriverCore.ts. The added rev-parse objects path, count-objects -v call, alternate listing, C-quoting, and temporary objects directory all serve the temporary object store mechanism. Without the alternate list, reads of existing history would fail under the new object directory, so these lines support the issue fix. The stated trade-off (recompression on a following commit and the added count-objects scan) follows from this mechanism and is disclosed. The test additions cover the no-leftover-objects behavior and alternate reads. No settings, contracts, or UI changes appear in the diff. I did not inspect the test file contents.

Finishing Touches

Generate unit tests (beta)

• Create a new PR

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

Recent review info

Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: main
• File: .coderabbit.config.ts
• Commit: eceeab4
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Advanced
• Run ID: f714e83b-61e6-4469-aaa4-e30b8241a691

Commits

Reviewing files that changed from the base of the PR and between 738afcd and 10d10c2.

Files selected for processing: 2

• apps/server/src/vcs/GitVcsDriverCore.test.ts
• apps/server/src/vcs/GitVcsDriverCore.ts

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 6 remain after this review.

[coderabbitai]

Additional comments: 1

apps/server/src/vcs/GitVcsDriverCore.ts-2550-2550: 1

2550-2550: Major · Performance & Scalability · Heavy lift

Unverified finding
Verification ran but could not confirm this finding. It is shown for review, not as a verified issue.

Avoid counting every object to discover alternates.

prepareCommitContext runs count-objects -v for every preparation. Git scans loose objects and pack metadata before it prints the alternate paths. If that scan exceeds the default 30-second Git timeout, preparation fails even when only one file needs staging. Enumerate alternates without counting objects, while retaining environment-provided and nested alternates. (raw.githubusercontent.com)

Review info

Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: main
• File: .coderabbit.config.ts
• Commit: eceeab4
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Advanced
• Run ID: 2c61d580-ab75-44c9-b891-d285b3ae9ae6

Commits

Reviewing files that changed from the base of the PR and between eceeab4 and 738afcd.

Files selected for processing: 2

• apps/server/src/vcs/GitVcsDriverCore.test.ts
• apps/server/src/vcs/GitVcsDriverCore.ts

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 7 remain after this review.

[juliusmarminge]

Evidence

In the real web app, add a never-staged file, open Commit changes, leave the message empty, and submit with text generation unavailable. After generation fails, run git hash-object <file> without -w, then git cat-file -e <hash>. Repeat in a linked worktree.

Observed: both blobs were initially absent. After failed preparation, both existed on base (exit 0) and remained absent on head (exit 1). No commit occurred, the real index stayed empty, and existing README history remained readable.

Environment for every capture: Linux, Chromium, 1280×800, light theme, fresh synthetic state. The labeled diagnostic panels display actual Git command output collected by the driver.

Capture	Before — eceeab4d5c	After — 10d10c270c
Normal repository: empty message
Normal repository: object check
Linked worktree: empty message
Linked worktree: shared object store
Recorded interaction	Before recording	After recording

Scenario and capture driver · Sanitized run transcript

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

Not shown:

• Nested shared-clone alternate chains, unusual quoted object-directory paths, and Windows were not exercised; this proof covers ordinary repositories and linked worktrees on Linux.