fix: fall back to feature dir basename for empty CURRENT_BRANCH (#3026)

[Noor-ul-ain001]

What

When a feature is resolved via SPECIFY_FEATURE_DIRECTORY or .specify/feature.json without SPECIFY_FEATURE set, get_current_branch() returns empty, so get_feature_paths / Get-FeaturePathsEnv emitted CURRENT_BRANCH= (empty) / BRANCH: "" even though the feature directory was fully resolvable. Downstream scripts and agents that expect a non-empty identifier got misleading, silent empty output.

Fixes #3026.

How

Fall back to the basename of the resolved feature directory when the branch is empty, in both resolvers:

• bash (scripts/bash/common.sh): current_branch="${feature_dir##*/}"
• PowerShell (scripts/powershell/common.ps1): $currentBranch = Split-Path -Leaf $featureDir

An explicit SPECIFY_FEATURE still takes precedence (it's read before this fallback), so this only fills the previously-empty case — no change for users who set the feature explicitly.

Verification

Reproduced end-to-end (bash), with SPECIFY_FEATURE unset and the feature pinned in feature.json:

=== BEFORE FIX ===  BRANCH= ''
=== AFTER FIX  ===  BRANCH= '001-my-feature'
=== AFTER FIX (SPECIFY_FEATURE=my-branch override) ===  BRANCH= 'my-branch'

Tests

Added regression tests (bash + PowerShell) to tests/test_check_prerequisites_paths_only.py:

• (test_|test_ps_)current_branch_falls_back_to_feature_dir_basename — BRANCH equals the feature dir basename when SPECIFY_FEATURE is unset.
• test_explicit_feature_still_overrides_basename — SPECIFY_FEATURE remains authoritative.

Verified the PowerShell test fails on main (empty BRANCH) and passes with the fix; existing paths-only tests still pass; ruff clean. (Bash tests run on CI; they skip on my local Windows pytest env where bash isn't on the pytest PATH, but I reproduced the bash behavior directly as shown above.)

🤖 Generated with Claude Code

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Pull request overview

This PR fixes a paths-only resolution edge case where feature context is resolvable (via SPECIFY_FEATURE_DIRECTORY or .specify/feature.json) but SPECIFY_FEATURE is unset, causing CURRENT_BRANCH/BRANCH to be emitted as an empty string. It adds a fallback that uses the resolved feature directory’s basename as a usable identifier, and introduces regression tests covering the behavior.

Changes:

• Bash: fall back to FEATURE_DIR basename when get_current_branch() is empty in get_feature_paths().
• PowerShell: apply the same basename fallback in Get-FeaturePathsEnv.
• Tests: add bash + PowerShell regression tests to assert the fallback behavior and that explicit SPECIFY_FEATURE remains authoritative.

Show a summary per file

File	Description
scripts/bash/common.sh	Adds CURRENT_BRANCH fallback to the resolved feature directory basename when explicit branch context is absent.
scripts/powershell/common.ps1	Adds the same fallback for CURRENT_BRANCH in the PowerShell resolver.
tests/test_check_prerequisites_paths_only.py	Adds regression tests validating the basename fallback and explicit override behavior for both bash and PowerShell.

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• Files reviewed: 3/3 changed files
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[mnriem]

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Review details

• Files reviewed: 3/3 changed files
• Comments generated: 1
• Review effort level: Low