feat(rust): port stack new to native Rust

[jd]

The Rust binary now serves mergify stack new <name> natively.
The Python implementation (mergify_cli/stack/new.py, its
click registration in mergify_cli/stack/cli.py, and the unit
suite in mergify_cli/tests/stack/test_new.py) is removed in
the same PR — the port-and-delete rule keeps a single live copy
of every command.

This is the first stack subcommand to land natively; the
rest still flow through the Python shim. The dispatcher peeks at
argv[0] after stack — when it's new, the rest is
secondary-parsed by clap and dispatched into
mergify_stack::commands::new; everything else continues to
forward to mergify-py-shim verbatim.

mergify stack new <NAME> [-b REMOTE/BRANCH] [--checkout/--no-checkout]:

1. Resolves the base ref. --base origin/main is used verbatim;
   otherwise mergify_stack::trunk::get_trunk mirrors the Python
   utils.get_trunk chain: branch.<current>.{remote,merge}
   tracking → refs/remotes/origin/HEAD fallback → set tracking
   on the current branch with a yellow notice → StackNotFound
   when both fail.
2. git fetch <remote> <branch> brings the base up to date.
3. git checkout --track -b <name> <base> (default) or
   git branch --track <name> <base> (--no-checkout)
   creates the branch.

Exit-code mapping matches Python: StackNotFound when the
trunk can't be resolved, GenericError for fetch/branch
failures, Success on the happy path.

The new mergify-stack::trunk module is reusable by future
stack drop/stack edit/stack sync ports — the helpers
git_get_branch_name, git_get_target_branch,
git_get_target_remote, and get_trunk are public.

mergify stack new --help is now served by clap; the bare
mergify stack --help still shims to Python and lists the
remaining Python-only subcommands.

Co-Authored-By: Claude Opus 4.7 noreply@anthropic.com

[mergify]

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[Copilot]

Pull request overview

This PR ports mergify stack new <NAME> from the Python shim to a native Rust implementation, and removes the Python command + its unit tests to keep a single live implementation during the migration. It also introduces a reusable mergify-stack::trunk module to resolve the trunk ref (<remote>/<branch>) for future native stack subcommands.

Changes:

• Add native Rust implementation of stack new plus dispatch in the Rust mergify binary.
• Add mergify-stack::trunk helpers to mirror Python’s trunk resolution and upstream auto-set behavior.
• Remove the Python stack new implementation, click registration, and Python unit tests for that subcommand.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
mergify_cli/tests/stack/test_new.py	Removes Python unit tests for the deleted Python stack new implementation.
mergify_cli/stack/new.py	Removes the Python implementation of stack new.
mergify_cli/stack/cli.py	Removes click wiring for the Python stack new subcommand.
crates/mergify-stack/src/trunk.rs	Adds Rust trunk-resolution module (tracking config → origin/HEAD fallback → auto-set upstream).
crates/mergify-stack/src/lib.rs	Exposes new commands and trunk modules from mergify-stack.
crates/mergify-stack/src/commands/new.rs	Adds Rust stack new implementation (fetch + branch creation) with unit tests.
crates/mergify-stack/src/commands/mod.rs	Introduces the commands module namespace for stack subcommands.
crates/mergify-cli/src/main.rs	Adds native dispatch for mergify stack new while keeping other stack subcommands shimmed.

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[mergify]

@jd this pull request is now in conflict 😩

[jd]

Revision history

#	Type	Changes	Reason	Date
1	initial	50050a2		2026-06-03 13:25 UTC
2	content	50050a2 → e5b00a8	rebase onto main, align parse_remote_branch error wording with Python trunk_type (Bc6GtplU), preserve underlying get_trunk error inside StackNotFound (Bc6Gtpl-), apply rustfmt	2026-06-03 13:25 UTC

[jd]

This pull request is part of a Mergify stack:

#	Pull Request	Link
1	feat(rust): port stack new to native Rust	#1513	👈
2	feat(rust): port stack note to native Rust	#1515

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-06-03 14:43 UTC · Rule: default
• ✅ Checks skipped · PR is already up-to-date
• ✅ Merged — 2026-06-03 14:43 UTC · at e5b00a8e721b200c66cc12f009a8cacc02dccc19 · squash

This pull request spent 12 seconds in the queue, including 2 seconds running CI.

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