Plan: Fix E2E failures after multi-tenant RC release#

Summary#

The multi-tenant RC merged several PRs (MT-1 through MT-12) that introduced regressions: DirectiveService's PlatformProvider is wired to a no-op default, PhaseRouterService doesn't apply mode directive changes via the webhook path, the webhook secret uses getOrThrow breaking E2E environments, and duplicate DI tokens create confusion.

Files#

File	Action	Description
`src/platform/github-platform.provider.ts`	create	Real GitHubPlatformProvider that delegates to GitHubService
`src/platform/platform.module.ts`	modify	Register GitHubPlatformProvider with useClass instead of no-op default
`src/phase-router/phase-router.service.ts`	modify	Apply mode directive changes (auto/quick/careful) in webhook path
`src/webhook/webhook.controller.ts`	modify	Change `getOrThrow` to `get` for GITHUB_WEBHOOK_SECRET, skip verification when unset
`src/tenant/tenant.constants.ts`	modify	Remove duplicate PLATFORM_PROVIDER, re-export from platform-provider.interface
`src/tenant/tenant.module.ts`	modify	Remove local PLATFORM_PROVIDER provision, import PlatformModule
`src/platform/github-platform.provider.spec.ts`	create	Unit tests for GitHubPlatformProvider
`src/phase-router/phase-router.service.spec.ts`	modify	Add test for mode directive handling in webhook path
`src/directive/directive.service.spec.ts`	modify	Update mock to verify real platform provider calls

Steps#

Create GitHubPlatformProvider implementing PlatformProvider by delegating postComment, closePR, deleteBranch to GitHubService.
Wire GitHubPlatformProvider in PlatformModule using useClass; remove no-op default. Import GitHubModule in PlatformModule.
Add mode directive handling in PhaseRouterService.route() step 2d — for auto/quick/careful, set task.directive and save before gate clearing.
Change GITHUB_WEBHOOK_SECRET from getOrThrow to get in webhook.controller.ts; skip signature verification when secret is empty/undefined.
Remove duplicate PLATFORM_PROVIDER from tenant.constants.ts; update tenant.module.ts to import from platform-provider.interface.ts and remove local provider.
Add unit tests for GitHubPlatformProvider, mode directive handling, and webhook secret skip logic.

Verification#

npm run test — all existing + new unit tests pass
npm run lint — zero warnings
npm run build — compiles cleanly

Risks#

Replacing the no-op PlatformProvider with a real one means DirectiveService now makes live GitHub API calls — ensure all spec mocks are updated to prevent real API calls in tests.
PhaseRouterService directive change is a behavior change: /agent auto via webhook now properly switches the task to auto mode, which changes downstream gating behavior.