* feat: post-merge build & test gate — Build step, iOS/Xcode, serial mode
Step 5.6 of execute-phase is extended per #2720:
- Renamed from "Post-merge test gate (parallel mode only)" to "Post-merge build & test gate"
- Gate now runs in both parallel mode (after worktree merge) and serial mode (after last plan)
- Added Step A: Build gate resolving BUILD_CMD from workflow.build_command config key, then auto-detecting via priority: config override → Xcode (.xcodeproj) → Makefile build: → Justfile → Cargo/Go/Python/npm. Xcode uses xcodebuild -list -json to get first scheme, then xcodebuild build -scheme ... -destination 'platform=iOS Simulator,name=iPhone 16'. Build failure increments WAVE_FAILURE_COUNT.
- Added Xcode/iOS detection to Step B (Test gate): when *.xcodeproj present and no workflow.test_command configured, uses xcodebuild test instead of the previous "no test runner detected" skip. Scheme reused from Step A when available.
- Documented workflow.build_command and workflow.test_command in docs/CONFIGURATION.md (table + JSON schema)
Closes#2720
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
* refactor(execute-phase): extract Step 5.6 body to post-merge-gate.md sub-file
Moves the build-detection logic and xcodebuild commands from the inline
Step 5.6 body into execute-phase/steps/post-merge-gate.md, replacing it
with a single Read() reference. Reduces execute-phase.md from 1755 to
1647 lines, satisfying the ≤1700 XL-tier budget enforced by
tests/workflow-size-budget.test.cjs.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>