rebase with preserve dates opt by skarim · Pull Request #96 · github/gh-stack

skarim · 2026-05-17T23:52:45Z

Add --committer-date-is-author-date flag to gh stack rebase

Introduce an opt-in --committer-date-is-author-date flag (with
--preserve-dates alias) for gh stack rebase. The flag is passed
through to every underlying git rebase invocation in the cascade,
keeping committer dates equal to author dates so that identical content
rebased onto an identical parent produces stable SHAs. This reduces
spurious force-push notifications and noisy review timelines, especially
in deep stacks where bottom branches get re-rebased on every merge.

Git layer changes:

Add RebaseOpts struct with CommitterDateIsAuthorDate field to
internal/git/gitops.go
Update Ops interface, defaultOps, public wrappers, and
rebaseContinueOnce/tryAutoResolveRebase helpers to accept and
forward the flag
Update MockOps to match the new signatures

Command layer changes:

Register --committer-date-is-author-date and --preserve-dates
flags on the cobra command in cmd/rebase.go
Add CommitterDateIsAuthorDate to cascadeRebaseOpts and thread it
to all git.Rebase/git.RebaseOnto calls in cmd/utils.go
Persist the flag in rebaseState JSON so --continue resumes with
the same behavior; pass it to RebaseContinue and subsequent cascade
calls
Update internal/modify/apply.go callers to pass zero-value
RebaseOpts{}

Tests:

Update all existing mock signatures in rebase, sync, and modify tests
Add tests for flag passthrough, --preserve-dates alias, state
round-trip, --continue flag restoration, and conflict state
persistence

Docs:

Update flag tables and examples in README.md and
docs/src/content/docs/reference/cli.md

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Copilot

Pull request overview

This PR adds an opt-in gh stack rebase flag (--committer-date-is-author-date with --preserve-dates alias) and threads it through the git layer so all cascade rebase operations can keep committer dates equal to author dates (improving SHA stability for identical rebases).

Changes:

Introduces git.RebaseOpts and updates git ops/wrappers/mocks to forward --committer-date-is-author-date into git rebase invocations (including continue/auto-resolve paths).
Adds CLI flags to gh stack rebase, persists the choice in rebaseState, and restores it on --continue.
Updates tests and documentation to cover flag passthrough, aliasing, and state round-tripping.

Show a summary per file

File	Description
README.md	Documents the new rebase flag and adds an example invocation.
docs/src/content/docs/reference/cli.md	Updates the CLI reference to include the new rebase flag and example.
internal/git/gitops.go	Adds `RebaseOpts`, updates `Ops` interface/default implementation to pass the new flag to `git rebase`.
internal/git/git.go	Threads `RebaseOpts` through public wrappers and rebase continue/auto-resolve helpers.
internal/git/mock_ops.go	Updates mock signatures to match the new `RebaseOpts`-accepting APIs.
cmd/rebase.go	Registers the new flags, persists/restores them via `rebaseState`, and forwards to cascade/continue.
cmd/utils.go	Threads the new option through cascade rebase calls (`Rebase`/`RebaseOnto`).
internal/modify/apply.go	Updates callers to pass zero-value `git.RebaseOpts{}`.
internal/modify/apply_test.go	Updates mock function signatures for the new git rebase APIs.
cmd/sync_test.go	Updates mock function signatures for the new git rebase APIs.
cmd/rebase_test.go	Adds/updates tests to validate flag passthrough, alias behavior, and state persistence.

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Files reviewed: 11/11 changed files
Comments generated: 3

Introduce an opt-in `--committer-date-is-author-date` flag (with `--preserve-dates` alias) for `gh stack rebase`. The flag is passed through to every underlying `git rebase` invocation in the cascade, keeping committer dates equal to author dates so that identical content rebased onto an identical parent produces stable SHAs. This reduces spurious force-push notifications and noisy review timelines, especially in deep stacks where bottom branches get re-rebased on every merge. Git layer changes: - Add `RebaseOpts` struct with `CommitterDateIsAuthorDate` field to `internal/git/gitops.go` - Update `Ops` interface, `defaultOps`, public wrappers, and `rebaseContinueOnce`/`tryAutoResolveRebase` helpers to accept and forward the flag - Update `MockOps` to match the new signatures Command layer changes: - Register `--committer-date-is-author-date` and `--preserve-dates` flags on the cobra command in `cmd/rebase.go` - Add `CommitterDateIsAuthorDate` to `cascadeRebaseOpts` and thread it to all `git.Rebase`/`git.RebaseOnto` calls in `cmd/utils.go` - Persist the flag in `rebaseState` JSON so `--continue` resumes with the same behavior; pass it to `RebaseContinue` and subsequent cascade calls - Update `internal/modify/apply.go` callers to pass zero-value `RebaseOpts{}` Tests: - Update all existing mock signatures in rebase, sync, and modify tests - Add tests for flag passthrough, `--preserve-dates` alias, state round-trip, `--continue` flag restoration, and conflict state persistence Docs: - Update flag tables and examples in README.md and docs/src/content/docs/reference/cli.md

ktravers

Looks good, left one question about naming (not blocking)

ktravers · 2026-05-26T19:19:33Z

 | `--continue` | Continue the rebase after resolving conflicts |
 | `--abort` | Abort the rebase and restore all branches to their pre-rebase state |
 | `--remote <name>` | Remote to fetch from (defaults to auto-detected remote) |
+| `--committer-date-is-author-date` | Set the committer date to the author date during rebase. Alias: `--preserve-dates` |


Wondering if there's a name that better reflects why this option exists, as opposed to literally what it's doing 🤔

The alias is pretty close. Any reason to not just use that and drop the lengthier --committer-date-is-author-date altogether? Or keep that as an internal only name?

Yeah it's unfortunate that the official flag in git is so long. Fwiw git's alias to --committer-date-is-author-date is --ignore-date, which I personally find very confusing. I opted to go with --preserve-dates as an alias because it is what made the most intuitive sense to me.

The intention of the command is to not change the committed date (and sometimes the commit sha, but only if the committer is also the author, among other conditions). I've thought about flipping the order so --preserve-dates is the primary and --committer-date-is-author-date is the alias, but imo aliases are generally supposed to be shorter and less detailed.

I don't love the naming, but I can't think of a better option either. Hoping that we can get this into users' hands and they can give us feedback on what makes sense or not 😅

skarim linked an issue May 17, 2026 that may be closed by this pull request

Support gh stack rebase --reset-author-date / --committer-date-is-author-date passthrough #34

Open

skarim force-pushed the skarim/sync-rebase branch from cedf847 to c46e74e Compare May 22, 2026 16:26

skarim force-pushed the skarim/rebase-preserve-date branch from 276321f to 5531d74 Compare May 22, 2026 16:26

skarim marked this pull request as ready for review May 23, 2026 21:32

Copilot AI review requested due to automatic review settings May 23, 2026 21:32

Copilot started reviewing on behalf of skarim May 23, 2026 21:32 View session

Copilot AI reviewed May 23, 2026

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skarim force-pushed the skarim/rebase-preserve-date branch from 5531d74 to 6daa31f Compare May 23, 2026 22:05

clearer wording in docs and help text

70f0b12

ktravers approved these changes May 26, 2026

View reviewed changes

skarim merged commit b219e96 into main May 26, 2026
6 checks passed

skarim deleted the skarim/rebase-preserve-date branch May 26, 2026 21:39

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rebase with preserve dates opt#96

rebase with preserve dates opt#96
skarim merged 2 commits into
skarim/sync-rebasefrom
skarim/rebase-preserve-date

skarim commented May 17, 2026

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skarim commented May 17, 2026

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