# Phase 6: Webhook Handler

**Status:** ✅ Complete
**Parent plan:** [PLAN.md](./PLAN.md)
**Domain:** backend

## Objective
Implement the secret UUID-based webhook endpoint that receives image push notifications from CI systems, with auto-creation of unknown projects.

## Tasks

- [x] Task 1: Implement webhook HTTP handler — `POST /api/webhook/:secret-uuid`
- [x] Task 2: Validate incoming payload — extract image name and tag
- [x] Task 3: Look up project by image name in store — match against configured project images
- [x] Task 4: If known project: match tag to stage via tag patterns, determine if auto_deploy
- [x] Task 5: If unknown project: auto-create project with defaults from image inspection (EXPOSE port, labels)
- [x] Task 6: Generate and store webhook secret UUID in settings (on first launch)
- [x] Task 7: Implement webhook URL regeneration (new UUID, invalidates old one)
- [x] Task 8: Define webhook payload struct (`{"image": "registry/org/app:tag"}`)

## Files to Modify/Create
- `internal/webhook/handler.go` — webhook HTTP handler + payload parsing
- `internal/webhook/matcher.go` — project/stage matching logic
- `internal/webhook/autocreate.go` — auto-create project from unknown image

## Acceptance Criteria
- Valid webhook URL with correct UUID triggers processing
- Invalid/missing UUID returns 404 (no information leak)
- Known images are matched to projects and stages
- Unknown images trigger auto-creation with sensible defaults
- Webhook URL can be regenerated

## Notes
- Webhook URL format: `POST /api/webhook/d8f2a1e9-...`
- No authentication needed beyond the secret UUID
- Auto-created projects use: image EXPOSE port, "dev" as default stage, auto_deploy: true
- The webhook handler calls into the deployer (Phase 7) — for now, define the interface/callback
- Keep the handler thin — it matches and delegates

## Review Checklist
- [x] All tasks completed
- [x] No information leak on invalid UUIDs
- [x] Payload validation rejects malformed input
- [x] Auto-creation uses safe defaults
- [x] Handler is stateless (delegates to store/deployer)

## Handoff to Next Phase

### Exported API

- `webhook.NewHandler(store, deployer, inspector)` — creates the HTTP handler
- `webhook.Handler.Route()` — returns a `chi.Router` to mount at `/api/webhook`
- `webhook.EnsureWebhookSecret(store)` — generates UUID on first launch, returns current secret
- `webhook.RegenerateWebhookSecret(store)` — replaces secret with new UUID, invalidates old one
- `webhook.ParseImageRef(ref)` — parses `registry/owner/name:tag` into components

### Interfaces Defined

- `webhook.DeployTriggerer` — `TriggerDeploy(ctx, projectID, stageID, imageTag) error` (mirrors `registry.DeployTriggerer`)
- `webhook.ImageInspector` — `InspectImage(ctx, imageRef) (docker.ImageInfo, error)` (wraps `docker.Client`)

### Integration Points

- Mount the webhook router: `r.Mount("/api/webhook", webhookHandler.Route())`
- Call `webhook.EnsureWebhookSecret(store)` at application startup to generate the secret on first launch
- The deployer must implement `webhook.DeployTriggerer` (same signature as `registry.DeployTriggerer`)
- The Docker client (`*docker.Client`) satisfies `webhook.ImageInspector` directly

### Auto-Create Behavior

- Unknown images create a project with name from image name, port from EXPOSE, healthcheck from image metadata
- A default "dev" stage is created with `tag_pattern: "*"`, `auto_deploy: true`, `max_instances: 1`
- If image inspection fails (not pulled locally), project is created with port=0 and empty healthcheck

### Tag Matching

- Uses `path.Match` (glob semantics) — same approach as the registry poller
- Stages are checked in name-sorted order; first matching stage wins
