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+# Backend-Agent Status Slice Design
+
+**Goal:** Stabilize the current backend foundation and add the first small, real backend-agent status path without introducing database or MQTT dependencies yet.
+
+**Architecture:** The backend keeps its existing in-memory/runtime-only character, but gains stronger HTTP test coverage and a minimal player status ingestion endpoint. The agent reuses its internal health snapshot and posts a compact status payload to the backend on a timer, so the first end-to-end data flow is exercised before larger sync and broker work begins.
+
+**Tech Stack:** Go stdlib HTTP server/client, existing repo docs, existing agent health model.
+
+---
+
+## Decision
+
+For the next slice, we intentionally do **not** implement full player registration, persistence, authentication, or MQTT.
+
+Instead we build a narrow vertical slice with these boundaries:
+
+1. harden existing backend routes and validation coverage
+2. add `POST /api/v1/player/status` in the backend with shared error handling
+3. add a small agent status reporter that periodically sends the current health snapshot
+4. document the temporary v1-dev contract clearly so later persistence and auth can replace it cleanly
+
+## Why this order
+
+### Option A - Recommended: backend hardening, then minimal status path
+
+Pros:
+
+- least architectural churn for the current repo stage
+- gives the project its first real backend-agent integration
+- keeps risk low because the payload is small and derived from already tested agent state
+- creates a natural foundation for later registration, revisions, and MQTT state
+
+Cons:
+
+- still not very visible to end users
+- uses temporary in-memory handling on the backend
+
+### Option B - Agent-first connectivity expansion
+
+Pros:
+
+- fast to implement in the agent
+- extends the new health model quickly
+
+Cons:
+
+- creates local connectivity logic without a meaningful server contract
+- duplicates future work once the backend path exists
+
+### Option C - Bigger vertical slice with registration and status
+
+Pros:
+
+- closer to the eventual architecture
+- more obviously “real” system behavior
+
+Cons:
+
+- too much surface area for the current codebase maturity
+- would mix lifecycle hardening, API design, auth placeholders, and agent behavior at once
+
+## Scope
+
+### Backend
+
+- keep `GET /healthz`, `GET /api/v1`, `GET /api/v1/meta`, and the existing `message-wall` route
+- add route-level tests for the existing endpoints
+- expand `message_wall` validation tests to match the documented rules more closely
+- add `POST /api/v1/player/status`
+- accept a small JSON payload and respond with a compact acknowledgement
+- no database write, no in-memory historical store yet beyond the request/response path unless needed for tests
+
+### Agent
+
+- keep the current lifecycle and health snapshot model
+- add an HTTP status reporter component that transforms the snapshot into a backend payload
+- send periodic status updates on a configurable interval
+- keep failures non-fatal and log them as structured events
+- no registration, no retries beyond the next normal interval, no MQTT yet
+
+## Proposed temporary API contract
+
+### Request
+
+`POST /api/v1/player/status`
+
+```json
+{
+  "screen_id": "info01-dev",
+  "ts": "2026-03-22T16:00:00Z",
+  "status": "running",
+  "server_url": "http://127.0.0.1:8080",
+  "mqtt_broker": "tcp://127.0.0.1:1883",
+  "heartbeat_every_seconds": 30,
+  "started_at": "2026-03-22T15:59:30Z",
+  "last_heartbeat_at": "2026-03-22T16:00:00Z"
+}
+```
+
+### Response
+
+```json
+{
+  "status": "accepted"
+}
+```
+
+### Notes
+
+- this is a dev-stage HTTP substitute for the richer future status/heartbeat model described in `API-MQTT-VERTRAG.md`
+- the payload is deliberately derived from fields the agent already owns today
+- later player identity, auth, richer connectivity flags, and persistence can evolve this contract without invalidating the current slice
+
+## Error handling
+
+- invalid JSON -> existing shared API error envelope with `400`
+- missing `screen_id` or invalid timestamps -> shared API error envelope with `400`
+- successful ingest -> `200` with compact acknowledgement
+- agent-side send failures -> structured log event, but the agent keeps running
+
+## Testing strategy
+
+### Backend tests
+
+- route tests for `/healthz`, `/api/v1`, `/api/v1/meta`
+- route tests for valid and invalid `POST /api/v1/player/status`
+- broaden `message_wall` validation tests for version, unit, fit mode, duplicate slots, out-of-bounds slots, empty slots
+
+### Agent tests
+
+- reporter payload generation from `HealthSnapshot`
+- status send success path using `httptest.Server`
+- non-fatal error handling on send failure
+- interval-driven reporting using injectable ticker/clock seams where needed
+
+## Out of scope
+
+- database persistence of player status
+- player registration
+- auth tokens
+- MQTT broker integration
+- screenshots and media sync
+- admin UI visualization of the status data
+
+## Expected result
+
+After this slice, the repository still remains intentionally simple, but it gains:
+
+- hardened backend route and validation coverage
+- the first real backend-agent HTTP interaction
+- a cleaner base for later registration, sync, and MQTT work
diff --git a/docs/plans/2026-03-22-backend-agent-status-plan.md b/docs/plans/2026-03-22-backend-agent-status-plan.md
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+# Backend-Agent Status Slice Implementation Plan
+
+> **For Claude:** REQUIRED SUB-SKILL: Use superpowers:executing-plans to implement this plan task-by-task.
+
+**Goal:** Harden the backend HTTP foundation and add the first minimal agent-to-backend status reporting path.
+
+**Architecture:** The backend remains a small in-memory Go service with stronger HTTP and validation tests plus a narrow `POST /api/v1/player/status` contract. The agent reuses its internal health snapshot and periodically posts it over HTTP, logging failures without stopping playback/lifecycle behavior.
+
+**Tech Stack:** Go stdlib, existing `net/http` router, `httptest`, existing agent health model.
+
+---
+
+### Task 1: Backend route coverage for existing endpoints
+
+**Files:**
+- Modify: `server/backend/internal/httpapi/messagewall_test.go`
+- Possibly create: `server/backend/internal/httpapi/router_test.go`
+
+**Step 1: Write the failing tests**
+
+Add focused tests for:
+- `GET /healthz` returns `200` and `status=ok`
+- `GET /api/v1` returns base info and tool list
+- `GET /api/v1/meta` returns the documented tool route
+
+**Step 2: Run test to verify it fails**
+
+Run: `go test ./internal/httpapi -run 'TestRouter'`
+Expected: FAIL because the new route tests do not exist yet or assertions fail.
+
+**Step 3: Write minimal implementation**
+
+Only add or adjust router/response code if the tests expose gaps. Do not refactor unrelated HTTP code.
+
+**Step 4: Run test to verify it passes**
+
+Run: `go test ./internal/httpapi -run 'TestRouter'`
+Expected: PASS.
+
+**Step 5: Commit**
+
+```bash
+git add server/backend/internal/httpapi/*.go
+git commit -m "Ergaenze HTTP-Tests fuer Basisendpunkte"
+```
+
+### Task 2: Message-wall validation matrix
+
+**Files:**
+- Modify: `server/backend/internal/campaigns/messagewall/resolver_test.go`
+
+**Step 1: Write the failing tests**
+
+Add table-driven validation tests for:
+- unsupported `version`
+- invalid `unit`
+- invalid `fit_mode`
+- empty slot list
+- duplicate `slot_id`
+- out-of-bounds slot
+
+**Step 2: Run test to verify it fails**
+
+Run: `go test ./internal/campaigns/messagewall -run 'TestValidate'`
+Expected: FAIL until the new cases are covered correctly.
+
+**Step 3: Write minimal implementation**
+
+Adjust validation only if tests reveal a real mismatch against `docs/LAYOUT-JSON.md`.
+
+**Step 4: Run test to verify it passes**
+
+Run: `go test ./internal/campaigns/messagewall -run 'TestValidate'`
+Expected: PASS.
+
+**Step 5: Commit**
+
+```bash
+git add server/backend/internal/campaigns/messagewall/resolver_test.go server/backend/internal/campaigns/messagewall/resolver.go
+git commit -m "Pruefe Layout-Validierung systematischer"
+```
+
+### Task 3: Backend player status endpoint
+
+**Files:**
+- Modify: `server/backend/internal/httpapi/router.go`
+- Create: `server/backend/internal/httpapi/playerstatus.go`
+- Create: `server/backend/internal/httpapi/playerstatus_test.go`
+
+**Step 1: Write the failing tests**
+
+Add tests for:
+- valid `POST /api/v1/player/status` returns `200` and `{"status":"accepted"}`
+- invalid JSON returns the shared error envelope
+- missing `screen_id` returns `400`
+- malformed timestamps return `400`
+
+**Step 2: Run test to verify it fails**
+
+Run: `go test ./internal/httpapi -run 'TestHandlePlayerStatus'`
+Expected: FAIL because handler and route do not exist yet.
+
+**Step 3: Write minimal implementation**
+
+Implement a small request struct, parse/validate it, and reuse the existing error/JSON helpers. Keep storage out of scope.
+
+**Step 4: Run test to verify it passes**
+
+Run: `go test ./internal/httpapi -run 'TestHandlePlayerStatus'`
+Expected: PASS.
+
+**Step 5: Commit**
+
+```bash
+git add server/backend/internal/httpapi/router.go server/backend/internal/httpapi/playerstatus.go server/backend/internal/httpapi/playerstatus_test.go
+git commit -m "Lege ersten Player-Status-Endpunkt an"
+```
+
+### Task 4: Agent status reporter payload
+
+**Files:**
+- Create: `player/agent/internal/statusreporter/reporter.go`
+- Create: `player/agent/internal/statusreporter/reporter_test.go`
+- Possibly modify: `player/agent/internal/app/app.go`
+
+**Step 1: Write the failing tests**
+
+Add tests for converting `app.HealthSnapshot` into the HTTP payload and for a successful post to an `httptest.Server`.
+
+**Step 2: Run test to verify it fails**
+
+Run: `go test ./internal/statusreporter`
+Expected: FAIL because package/behavior does not exist yet.
+
+**Step 3: Write minimal implementation**
+
+Create a small reporter with injected base URL, `http.Client`, and time source as needed. Keep the API narrow.
+
+**Step 4: Run test to verify it passes**
+
+Run: `go test ./internal/statusreporter`
+Expected: PASS.
+
+**Step 5: Commit**
+
+```bash
+git add player/agent/internal/statusreporter/*.go player/agent/internal/app/app.go
+git commit -m "Fuehre einfachen Status-Reporter fuer den Agenten ein"
+```
+
+### Task 5: Agent periodic reporting integration
+
+**Files:**
+- Modify: `player/agent/internal/app/app.go`
+- Modify: `player/agent/internal/app/app_test.go`
+- Possibly modify: `player/agent/internal/config/config.go`
+- Possibly modify: `player/agent/internal/config/config_test.go`
+
+**Step 1: Write the failing tests**
+
+Add tests that prove:
+- reporting is triggered from the running app
+- send failures are logged and do not stop `Run()`
+- any new interval config gets sane defaults
+
+**Step 2: Run test to verify it fails**
+
+Run: `go test ./internal/app ./internal/config`
+Expected: FAIL until integration exists.
+
+**Step 3: Write minimal implementation**
+
+Wire the reporter into the app loop with the smallest possible seam. Avoid broad lifecycle refactors.
+
+**Step 4: Run test to verify it passes**
+
+Run: `go test ./internal/app ./internal/config`
+Expected: PASS.
+
+**Step 5: Commit**
+
+```bash
+git add player/agent/internal/app/*.go player/agent/internal/config/*.go
+git commit -m "Melde Agent-Status periodisch an das Backend"
+```
+
+### Task 6: Documentation update for the new status path
+
+**Files:**
+- Modify: `API-MQTT-VERTRAG.md`
+- Modify: `DEVELOPMENT.md`
+- Possibly modify: `README.md`
+- Possibly create: `docs/PLAYER-STATUS-HTTP.md`
+
+**Step 1: Write the failing documentation check**
+
+Create a short checklist from the implemented contract and verify which docs are stale.
+
+**Step 2: Run the verification**
+
+Manual check against the implemented request/response payload and the chosen scope.
+Expected: current docs are incomplete for the temporary dev-stage HTTP status path.
+
+**Step 3: Write minimal documentation updates**
+
+Document that the current dev slice uses a minimal HTTP status endpoint before the richer long-term API/MQTT model is fully built.
+
+**Step 4: Run verification**
+
+Re-read the changed docs and ensure wording matches actual code scope.
+
+**Step 5: Commit**
+
+```bash
+git add API-MQTT-VERTRAG.md DEVELOPMENT.md README.md docs/*.md
+git commit -m "Dokumentiere ersten HTTP-Statuspfad fuer den Agenten"
+```
+
+### Task 7: Final verification
+
+**Files:**
+- No planned file changes
+
+**Step 1: Run backend tests**
+
+Run: `go test ./...`
+Workdir: `server/backend`
+Expected: PASS.
+
+**Step 2: Run agent tests**
+
+Run: `go test ./...`
+Workdir: `player/agent`
+Expected: PASS.
+
+**Step 3: Run builds**
+
+Run:
+- `go build ./...` in `server/backend`
+- `go build ./...` in `player/agent`
+Expected: PASS.
+
+**Step 4: Run manual integration check**
+
+Start backend locally, run agent locally with example config, and confirm the backend receives `POST /api/v1/player/status` successfully.
+
+**Step 5: Commit if needed**
+
+Only if the verification step itself required code/doc adjustments.