feat(ci): add native mobile build validation

[up-tandem]

Summary

• Add conditional build-ios CI job that compiles the iOS app for Simulator when mobile iOS changes are detected
• Add conditional build-android CI job that assembles the Android debug APK when mobile Android changes are detected
• Both jobs reuse existing affected job outputs and run in parallel with lint jobs

Resolves #82

Contracts Changed

No

Regeneration Required

No

Validation

• YAML validated (8 jobs: commits, affected, generated-code, build-and-test, lint-ios, build-ios, lint-android, build-android)
• Existing lint-ios and lint-android jobs unchanged
• Build jobs conditional on affected detection (same pattern as lint jobs)
• Build failures will block merge via standard CI checks

🤖 Generated with Claude Code

Summary by CodeRabbit

• Chores
  • CI now performs platform-specific builds for iOS and Android (including platform setup and caching) in addition to existing checks, expanding automated build coverage.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: af3a90b6-f07d-4162-87a9-b7a1bcdd68fe

📥 Commits

Reviewing files that changed from the base of the PR and between b1258c3 and fc2a423.

📒 Files selected for processing (1)

• .github/workflows/ci.yml

---

Walkthrough

Adds two conditional CI jobs to the GitHub Actions workflow: build-ios runs an Xcode build when iOS targets are affected; build-android runs a Gradle assembleDebug when Android targets are affected. Both include checkout, cache setup, and platform-specific tool setup.

Changes

Cohort / File(s)	Summary
CI Workflow Mobile Build Jobs .github/workflows/ci.yml	Add build-ios and build-android jobs gated by affected outputs (mobile_ios, mobile_android). Each job includes Checkout, platform toolchain/setup (iOS DerivedData cache; Java/Gradle setup and caches for Android), and a platform-specific build step (xcodebuild for ForgeApp iOS project; ./gradlew assembleDebug for Android). Existing lint jobs remain unchanged.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  participant GH as GitHub Actions
  participant Repo as Repository
  participant Cache as Cache (actions/cache)
  participant Tool as Toolchain (Xcode / Java+Gradle)
  participant Builder as Build system (xcodebuild / gradlew)

  GH->>Repo: checkout code
  GH->>Cache: restore caches (DerivedData / Gradle)
  GH->>Tool: setup platform tools
  Tool->>Builder: invoke build command
  Builder-->>GH: success / failure status
  GH-->>Cache: save updated caches

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Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat(ci): add native mobile build validation' accurately summarizes the main change: adding native mobile build validation to the CI workflow.
Linked Issues check	✅ Passed	All acceptance criteria from issue #82 are met: build-ios and build-android jobs added with conditional triggers, existing lint jobs unchanged, build failures will block merges, and affected-path detection is properly utilized.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to issue #82 objectives; only CI workflow modifications for mobile build jobs are present with no unrelated changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/82-ci-mobile-builds

---

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[coderabbitai]

🧹 Nitpick comments (1)

.github/workflows/ci.yml (1)

121-134: Consider adding DerivedData caching to speed up iOS builds.

The build-android job includes a Gradle cache step, but build-ios has no caching. Adding a cache for xcodebuild's DerivedData directory (similar to the Android caching pattern) would improve build times on subsequent runs:

- name: Cache DerivedData
  uses: actions/cache@v4
  with:
    path: |
      ~/Library/Developer/Xcode/DerivedData
    key: ${{ runner.os }}-xcode-${{ hashFiles('**/Package.resolved') }}
    restore-keys: |
      ${{ runner.os }}-xcode-

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In @.github/workflows/ci.yml around lines 121 - 134, The build-ios job is
missing DerivedData caching which slows repeated xcodebuild runs; add a cache
step named like "Cache DerivedData" before the "Build iOS (Simulator)" step that
uses actions/cache@v4 to cache ~/Library/Developer/Xcode/DerivedData (use a key
based on runner.os and a project hash such as hashFiles('**/Package.resolved')
and a restore-keys fallback like '${{ runner.os }}-xcode-') so subsequent runs
of the xcodebuild step (project mobile/ios/App/ForgeApp.xcodeproj, scheme
ForgeApp, destination 'generic/platform=iOS Simulator') restore DerivedData and
speed up builds.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In @.github/workflows/ci.yml:
- Around line 121-134: The build-ios job is missing DerivedData caching which
slows repeated xcodebuild runs; add a cache step named like "Cache DerivedData"
before the "Build iOS (Simulator)" step that uses actions/cache@v4 to cache
~/Library/Developer/Xcode/DerivedData (use a key based on runner.os and a
project hash such as hashFiles('**/Package.resolved') and a restore-keys
fallback like '${{ runner.os }}-xcode-') so subsequent runs of the xcodebuild
step (project mobile/ios/App/ForgeApp.xcodeproj, scheme ForgeApp, destination
'generic/platform=iOS Simulator') restore DerivedData and speed up builds.

---

ℹ️ Review info

Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: f6c29190-30e6-4d19-bc11-0dfb8b9b337e

📥 Commits

Reviewing files that changed from the base of the PR and between 0b7321c and b1258c3.

📒 Files selected for processing (1)

• .github/workflows/ci.yml

[up-tandem]

Review feedback addressed (fc2a423)

Fixed:

• [CodeRabbit nitpick: add DerivedData caching to build-ios]: Added actions/cache@v4 step for ~/Library/Developer/Xcode/DerivedData keyed on Package.swift hash, matching the Gradle caching pattern in build-android.

Not changed:

• build-and-test failure is pre-existing on main (TypeScript error in apps/web — Property 'id' does not exist on type 'Section'). Not related to this PR.