feat: Worktree navigation via wt go, launcher via wt open

[sahil-noon]

Meta

ID	Type	Confidence	Plan	Review
3pp5	feat	4.6/5.0	9/9 tasks, 20/20 acceptance ✓	✓ 1 cycle

Pipeline: intake ✓ → apply ✓ → review ✓ → hydrate ✓ → ship → review-pr

Impact: +531/−56 code (excluding fab/, docs/) · +1455/−66 total

Summary

From inside a worktree, there is no low-friction way to discover and jump to a sibling worktree — the selection menu is locked to the main repo, and the no-arg wt open from within a worktree opens the current folder. The acts of "pick which worktree" and "launch a directory in a tool" are fused into a single overloaded open verb, blocking the clean division of labor the toolchain is built around. This change introduces wt go as the dedicated worktree-selection verb, narrows wt open toward a pure launcher, and adds wt open --go as an ergonomic composition of both — reusing the existing WT_CD_FILE shell-cd mechanism with no new plumbing.

Changes

• New wt go [name] subcommand — current-repo worktree selection (Act 2); no-arg shows a menu, positional arg resolves directly; navigates via WT_CD_FILE and prints the resolved path to stdout for scripting
• wt open narrowed toward pure launcher (Act 1) — all existing invocations preserved, behavior unchanged for hop consumers
• New --go flag on wt open — select-then-launch composition; wt open --go shows the worktree menu then launches, wt open --go <name> resolves then launches, --go --app composes
• Shared selectWorktree helper extracted from selectAndOpen so both wt go and wt open --go share a single selection source of truth
• Docs and specs: cli-surface.md, launcher-contract.md, new go-command-contract.md memory file

[Copilot]

Pull request overview

This PR introduces a clearer split between worktree selection/navigation and directory launching by adding a dedicated wt go selector command, narrowing wt open toward launcher behavior, and enabling an ergonomic composition via wt open --go.

Changes:

• Add wt go [name] for current-repo worktree selection and navigation via WT_CD_FILE + stdout.
• Add --go flag to wt open to select a worktree first (menu or name) and then launch it (optionally composing with --app).
• Extract shared worktree-selection logic into selectWorktree(...) so open, go, and open --go use one menu implementation.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/cmd/wt/open.go	Adds --go composition path, extracts shared selectWorktree, and refactors --app handling into openInNamedApp.
src/cmd/wt/main.go	Registers the new go subcommand on the root CLI.
src/cmd/wt/go.go	Implements wt go selector + navigateTo (WT_CD_FILE + stdout) behavior.
src/cmd/wt/go_test.go	Adds unit-style binary tests for wt go behavior and exit codes.
src/cmd/wt/integration_test.go	Adds end-to-end coverage for sibling-worktree navigation and wt open --go composition.
src/cmd/wt/help_dump_test.go	Updates visible-subcommand expectations to include go.
docs/specs/cli-surface.md	Documents wt go and wt open --go (note: exit-code summary needs alignment—comment left).
docs/specs/launcher-contract.md	Notes wt go reuses WT_CD_FILE semantics without changing the contract.
docs/memory/wt-cli/go-command-contract.md	Adds a memory/contract capture for wt go + wt open --go.
docs/memory/wt-cli/index.md	Adds entry for the new memory file (note: “Last Updated” placeholder needs fixing—comment left).
docs/memory/wt-cli/recency-ordering-contract.md	Updates recency-ordering memory to include wt go as a consumer via selectWorktree.
docs/memory/wt-cli/menu-navigation-contract.md	Updates menu-navigation memory to include wt go / open --go call paths.
fab/changes/260620-3pp5-open-worktree-from-worktree/*	Captures planning/intake/status/history artifacts for this change.

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[sahil-noon]

Fixed — the wt open exit-code summary now lists ExitGitError for the --go non-git-cwd precondition, alongside the name-resolution git-op case. (08e0a1f)