test: add Pact consumer contract for astrolabe credentials status (ADR-029)

Introduce consumer-driven contract testing between nextcloud-mcp-server and the
astrolabe Nextcloud app, published to the homelab Pact Broker and verified in CI.

- pact-python dev dep + `contract` pytest marker
- tests/contract/test_astrolabe_credentials_consumer.py: consumer pact for the
  background-sync *status* call (provisioned -> has_background_access:true,
  sync_type:"app_password", integer provisioned_at; unprovisioned -> false/null)
- tests/contract/test_mcp_provider_verification.py: env-gated Verifier harness
  for this server's /api/v1/* provider role (provider-state handlers stubbed
  pending astrolabe's published pacts)
- .github/workflows/pact.yml: join tailnet -> publish pacts -> provider verify
  -> can-i-deploy; broker steps skip when PACT_BROKER is unset (forks)
- docs/ADR-029-pact-contract-testing.md

Fix astrolabe_client.get_background_sync_status: it previously read a
non-existent `app_password` field (always reporting no-access). Rewrite it to
read the real status contract (has_background_access / sync_type /
provisioned_at) and drop the unsatisfiable get_user_app_password.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.github/workflows/pact.yml

@@ -0,0 +1,155 @@
+name: Pact contract tests
+
+# Consumer-driven contract testing against the homelab-hosted Pact Broker
+# (ADR-029). The broker is only reachable over Tailscale, so every job that
+# talks to it first joins the tailnet with the shared github-runner OAuth
+# client. Jobs no-op when the broker secrets are absent (e.g. on forks).
+#
+# Required repo/org secrets:
+#   TS_OAUTH_CLIENT_ID / TS_OAUTH_SECRET  - Tailscale github-runner OAuth client
+#   PACT_BROKER                           - broker base URL (https://pact-broker.internal.coutinho.io)
+#   PACT_USERNAME / PACT_PASSWORD         - broker basic-auth credentials
+
+on:
+  pull_request:
+    branches:
+      - master
+  push:
+    branches:
+      - master
+
+concurrency:
+  group: pact-${{ github.ref }}
+  cancel-in-progress: true
+
+env:
+  PACT_BROKER: ${{ secrets.PACT_BROKER }}
+  PACT_USERNAME: ${{ secrets.PACT_USERNAME }}
+  PACT_PASSWORD: ${{ secrets.PACT_PASSWORD }}
+
+jobs:
+  consumer:
+    name: Consumer pacts (mcp -> astrolabe)
+    runs-on: ubuntu-latest
+    # Skip on forks / when broker is not configured.
+    if: ${{ github.event_name == 'push' || github.event.pull_request.head.repo.full_name == github.repository }}
+    steps:
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+
+      - name: Install the latest version of uv
+        uses: astral-sh/setup-uv@37802adc94f370d6bfd71619e3f0bf239e1f3b78 # v7.6.0
+
+      - name: Generate consumer pacts
+        run: uv run pytest -v -m contract -o "addopts=-p no:asyncio" tests/contract/
+
+      # Only publish from non-fork builds that have the broker secrets.
+      - name: Join tailnet
+        if: ${{ env.PACT_BROKER != '' }}
+        uses: tailscale/github-action@v3
+        with:
+          oauth-client-id: ${{ secrets.TS_OAUTH_CLIENT_ID }}
+          oauth-secret: ${{ secrets.TS_OAUTH_SECRET }}
+          tags: tag:github-runner
+
+      - name: Install Pact CLI
+        if: ${{ env.PACT_BROKER != '' }}
+        run: |
+          curl -fsSL https://raw.githubusercontent.com/pact-foundation/pact-ruby-standalone/master/install.sh | bash
+          echo "$PWD/pact/bin" >> "$GITHUB_PATH"
+
+      - name: Publish pacts to broker
+        if: ${{ env.PACT_BROKER != '' }}
+        run: |
+          pact-broker publish tests/contract/pacts \
+            --broker-base-url "$PACT_BROKER" \
+            --broker-username "$PACT_USERNAME" \
+            --broker-password "$PACT_PASSWORD" \
+            --consumer-app-version "${{ github.sha }}" \
+            --branch "${{ github.head_ref || github.ref_name }}"
+
+  provider:
+    name: Provider verification (astrolabe -> mcp)
+    runs-on: ubuntu-latest
+    if: ${{ github.event_name == 'push' || github.event.pull_request.head.repo.full_name == github.repository }}
+    steps:
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+
+      - name: Install the latest version of uv
+        uses: astral-sh/setup-uv@37802adc94f370d6bfd71619e3f0bf239e1f3b78 # v7.6.0
+
+      # Stand up the MCP server. NOTE: single-user only exposes the *public*
+      # management endpoints (/api/v1/status, /api/v1/vector-sync/status) — see
+      # app.py:2248. The authenticated surface astrolabe also consumes
+      # (/api/v1/search, /webhooks, /apps, /chunk-context, /pdf-preview) needs
+      # an OAuth-capable profile (login-flow) plus Bearer-token injection into
+      # the verifier (Verifier.add_custom_header). That is the phase-4 follow-up;
+      # this job currently verifies the public-endpoint pacts.
+      - name: Generate ephemeral TOKEN_ENCRYPTION_KEY
+        run: |
+          KEY=$(openssl rand -base64 32 | tr '+/' '-_')
+          echo "TOKEN_ENCRYPTION_KEY=${KEY}" >> "$GITHUB_ENV"
+
+      - name: Start MCP server
+        uses: hoverkraft-tech/compose-action@11beaa1c2dae4e8ed7b1665aa074723b6cecb0e4 # v3.0.0
+        with:
+          compose-file: "./docker-compose.yml"
+          compose-flags: "--profile single-user"
+          up-flags: "--build"
+        env:
+          TOKEN_ENCRYPTION_KEY: ${{ env.TOKEN_ENCRYPTION_KEY }}
+
+      - name: Wait for MCP server
+        run: |
+          for i in $(seq 1 30); do
+            code=$(curl -o /dev/null -s -w "%{http_code}" http://localhost:8000/api/v1/status || true)
+            [ "$code" = "200" ] && echo "ready" && exit 0
+            sleep 5
+          done
+          docker compose --profile single-user logs mcp
+          exit 1
+
+      - name: Join tailnet
+        if: ${{ env.PACT_BROKER != '' }}
+        uses: tailscale/github-action@v3
+        with:
+          oauth-client-id: ${{ secrets.TS_OAUTH_CLIENT_ID }}
+          oauth-secret: ${{ secrets.TS_OAUTH_SECRET }}
+          tags: tag:github-runner
+
+      - name: Verify provider against broker pacts
+        if: ${{ env.PACT_BROKER != '' }}
+        env:
+          PACT_PROVIDER_URL: http://localhost:8000
+          PACT_PROVIDER_VERSION: ${{ github.sha }}
+          PACT_PROVIDER_BRANCH: ${{ github.head_ref || github.ref_name }}
+          # Publish results only from master so PR runs don't pollute the matrix.
+          PACT_PUBLISH_RESULTS: ${{ github.ref == 'refs/heads/master' }}
+        run: uv run pytest -v -m contract -o "addopts=-p no:asyncio" tests/contract/test_mcp_provider_verification.py
+
+  can-i-deploy:
+    name: can-i-deploy
+    runs-on: ubuntu-latest
+    needs: [consumer, provider]
+    if: ${{ github.ref == 'refs/heads/master' }}
+    steps:
+      - name: Join tailnet
+        uses: tailscale/github-action@v3
+        with:
+          oauth-client-id: ${{ secrets.TS_OAUTH_CLIENT_ID }}
+          oauth-secret: ${{ secrets.TS_OAUTH_SECRET }}
+          tags: tag:github-runner
+
+      - name: Install Pact CLI
+        run: |
+          curl -fsSL https://raw.githubusercontent.com/pact-foundation/pact-ruby-standalone/master/install.sh | bash
+          echo "$PWD/pact/bin" >> "$GITHUB_PATH"
+
+      - name: Can I deploy nextcloud-mcp-server?
+        run: |
+          pact-broker can-i-deploy \
+            --broker-base-url "$PACT_BROKER" \
+            --broker-username "$PACT_USERNAME" \
+            --broker-password "$PACT_PASSWORD" \
+            --pacticipant nextcloud-mcp-server \
+            --version "${{ github.sha }}" \
+            --to-environment production

.gitignore

@@ -24,3 +24,6 @@ docker-compose.override.yml
 
 # RAG Evaluation
 tests/rag_evaluation/fixtures/
+
+# Pact contract tests — generated pacts are published to the broker, not committed
+tests/contract/pacts/

docs/ADR-029-pact-contract-testing.md

@@ -0,0 +1,109 @@
+# ADR-029: Pact contract testing with astrolabe
+
+## Status
+
+Accepted — 2026-06-10
+
+## Context
+
+`nextcloud-mcp-server` (Python/FastMCP) and the `astrolabe` Nextcloud app (PHP)
+integrate over HTTP **in both directions**:
+
+- **MCP server → astrolabe** (one call): the background vector-sync reads a
+  user's provisioning **status** via
+  `GET /apps/astrolabe/api/v1/background-sync/credentials/{user_id}`
+  (`nextcloud_mcp_server/auth/astrolabe_client.py`). This returns status only —
+  `{success, user_id, has_background_access, sync_type, provisioned_at}`, always
+  HTTP 200, and **never the password**. The app password itself flows the other
+  way: astrolabe pushes it to the MCP server's `/api/v1/users/{uid}/app-password`.
+- **astrolabe → MCP server** (~10 calls): astrolabe's `McpServerClient` consumes
+  this server's `/api/v1/*` HTTP API — `status`, `vector-sync/status`, `search`,
+  `vector-viz/search`, `webhooks` (GET/POST/DELETE), `apps`, `chunk-context`,
+  `pdf-preview` (`nextcloud_mcp_server/app.py` route table, `api/webhooks.py`).
+
+Today nothing guarantees the two stay wire-compatible. A renamed JSON field or a
+changed status code on either side is only caught — if at all — by the heavy
+integration matrix (docker-compose, real Nextcloud, minutes per run). We want a
+fast, focused signal that fails the moment the contract drifts, runnable in
+unit-style CI on either repo independently.
+
+## Decision
+
+Adopt **consumer-driven contract testing with Pact**, with a self-hosted **Pact
+Broker in the homelab** as the system of record. GitHub Actions reach the broker
+**over Tailscale** (the broker is not publicly exposed).
+
+Because the integration is bidirectional, each repo plays **both** Pact roles:
+
+| Contract | Consumer | Provider | Consumer tooling | Provider tooling |
+|----------|----------|----------|------------------|------------------|
+| credentials API | nextcloud-mcp-server | astrolabe | `pact-python` | `pact-php` verifier |
+| `/api/v1/*` API | astrolabe | nextcloud-mcp-server | `pact-php` | `pact-python` `Verifier` |
+
+### This repo (Python side)
+
+- `pact-python` (v3 API, `from pact import Pact, Verifier, match`) is a **dev**
+  dependency.
+- Contract tests live under `tests/contract/` behind a `contract` pytest marker,
+  kept out of the default `unit` run.
+  - **Consumer** (`test_astrolabe_credentials_consumer.py`): drives the real
+    `AstrolabeClient` against a Pact mock server, pinning the request shape and
+    the two status responses it branches on — provisioned
+    (`has_background_access: true`, `sync_type: "app_password"`, integer
+    `provisioned_at`) and unprovisioned (`has_background_access: false`). The
+    OAuth token fetch is stubbed so only the credentials call is exercised.
+    Interactions merge into `tests/contract/pacts/` (git-ignored — pacts are
+    published to the broker, not committed).
+  - **Provider** (`test_mcp_provider_verification.py`): a `Verifier` harness that
+    replays astrolabe's published pacts against a running MCP server. It is
+    **environment-gated** (`PACT_PROVIDER_URL` + a pact source) so it skips in
+    the consumer-only job and in local runs. Provider-state handlers are
+    registered by `given(...)` string in `_PROVIDER_STATES` and filled in as
+    astrolabe publishes its consumer pacts; unknown states no-op so state-less
+    interactions (`/api/v1/status`, `/api/v1/vector-sync/status`) verify
+    immediately.
+
+### CI (`.github/workflows/pact.yml`)
+
+Three jobs, each joining the tailnet with the shared `tag:github-runner` OAuth
+client before touching the broker:
+
+1. **consumer** — generate pacts, publish to the broker tagged with the branch
+   and commit SHA.
+2. **provider** — stand up the MCP server (single-user compose profile), verify
+   astrolabe's pacts against it, publish verification results (master only).
+3. **can-i-deploy** — gate `master` on `pact-broker can-i-deploy … --pacticipant
+   nextcloud-mcp-server --to-environment production`.
+
+Broker-dependent steps are skipped when `PACT_BROKER` is unset (forks).
+
+### Infrastructure (other repos / sessions)
+
+- **Broker**: `pactfoundation/pact-broker` deployed via ArgoCD
+  (`homelab-argocd`), backed by the shared Zalando Postgres, reachable at
+  `pact-broker.internal.coutinho.io`. Single basic-auth credential from AWS
+  Secrets Manager via external-secrets.
+- **CI access**: jobs join the tailnet (`tag:github-runner`) and reach the
+  broker via the `PACT_BROKER` secret (its Tailscale host). No new Terraform is
+  required.
+
+### Required secrets (this repo)
+
+`TS_OAUTH_CLIENT_ID`, `TS_OAUTH_SECRET` (Tailscale github-runner OAuth client),
+`PACT_BROKER` (base URL), `PACT_USERNAME`, `PACT_PASSWORD` (broker basic auth).
+
+## Consequences
+
+- **Fast, independent signal**: either side detects an incompatible change in a
+  ~seconds-long job instead of waiting on the integration matrix.
+- **Participant names are load-bearing**: the consumer/provider names
+  (`nextcloud-mcp-server`, `astrolabe`) must match exactly across both repos and
+  the broker. They live in `tests/contract/conftest.py` here and must mirror the
+  astrolabe pact tests.
+- **Provider states are deferred work**: the `/api/v1/*` provider verification is
+  only as complete as the state handlers that seed its backends (webhooks DB,
+  Qdrant). These land incrementally as astrolabe publishes its consumer pacts.
+- **Broker is a homelab dependency**: contract publication/verification needs the
+  tailnet and the broker up. Steps degrade to skipped (not failed) when the
+  broker is unreachable from a fork; on `master` an outage will fail
+  `can-i-deploy`.

nextcloud_mcp_server/auth/astrolabe_client.py

@@ -91,24 +91,32 @@ class AstrolabeClient:
             logger.info("Obtained Astrolabe API token (expires in %ss)", expires_in)
             return data["access_token"]
 
-    async def get_user_app_password(self, user_id: str) -> Optional[str]:
+    async def get_background_sync_status(self, user_id: str) -> dict:
         """
-        Retrieve user's app password for background sync.
+        Get background sync provisioning status for a user.
+
+        Queries Astrolabe's admin credentials-metadata endpoint, which returns
+        presence/timestamps only — never the app password itself. The password
+        is delivered to the MCP server out-of-band (Astrolabe pushes it to
+        ``POST /api/v1/users/{user_id}/app-password``), so this endpoint exposes
+        only ``has_background_access`` / ``sync_type`` / ``provisioned_at``.
 
         Args:
             user_id: Nextcloud user ID
 
         Returns:
-            App password string, or None if user hasn't provisioned
+            Dict with keys: has_access (bool), credential_type (str | None),
+            provisioned_at (int | None) — Unix seconds, not an ISO string.
 
         Raises:
-            httpx.HTTPError: If API request fails (except 404)
+            httpx.HTTPError: If the API request fails (except 404, treated as
+            "not provisioned").
         """
         token = await self.get_access_token()
         url = f"{self.nextcloud_host}/apps/astrolabe/api/v1/background-sync/credentials/{user_id}"
 
         async with nextcloud_httpx_client() as client:
-            logger.debug("Retrieving app password for user: %s", user_id)
+            logger.debug("Fetching background-sync status for user: %s", user_id)
 
             response = await client.get(
                 url,
@@ -117,38 +125,24 @@ class AstrolabeClient:
             )
 
             if response.status_code == 404:
-                logger.debug("No app password configured for user: %s", user_id)
+                logger.debug("No background-sync credentials for user: %s", user_id)
-                return None
+                return {
+                    "has_access": False,
+                    "credential_type": None,
+                    "provisioned_at": None,
+                }
 
             response.raise_for_status()
             data = response.json()
 
+            has_access = bool(data.get("has_background_access"))
             logger.info(
-                "Retrieved app password for user: %s (type: %s)",
+                "Background-sync status for user %s: has_access=%s",
                 user_id,
-                data.get("credential_type"),
+                has_access,
             )
-            return data.get("app_password")
+            return {
-
+                "has_access": has_access,
-    async def get_background_sync_status(self, user_id: str) -> dict:
+                "credential_type": data.get("sync_type"),
-        """
+                "provisioned_at": data.get("provisioned_at"),
-        Get background sync status for a user.
+            }
-
-        Args:
-            user_id: Nextcloud user ID
-
-        Returns:
-            Dict with keys: has_access, credential_type, provisioned_at
-
-        Raises:
-            httpx.HTTPError: If API request fails
-        """
-        # For now, check if app password exists
-        # In the future, this could query a dedicated status endpoint
-        app_password = await self.get_user_app_password(user_id)
-
-        return {
-            "has_access": app_password is not None,
-            "credential_type": "app_password" if app_password else None,
-            "provisioned_at": None,  # TODO: Get from API if available
-        }

pyproject.toml

@@ -81,6 +81,7 @@ markers = [
     "login_flow: Login Flow v2 integration tests (ADR-022)",
     "multi_user_basic: Multi-user BasicAuth pass-through tests (ADR-020)",
     "postgres: Tests requiring the docker-compose postgres-test service (ADR-026)",
+    "contract: Pact consumer/provider contract tests (ADR-029)",
 ]
 testpaths = [
     "tests",
@@ -128,6 +129,7 @@ dev = [
     "pytest-otel>=2.0.1",
     "procrastinate>=3.8",
     "psycopg[binary,pool]>=3.2",
+    "pact-python>=3.4.0",
 ]
 
 [project.scripts]

tests/contract/__init__.py

@@ -0,0 +1,12 @@
+"""Pact consumer/provider contract tests (ADR-029).
+
+This package contains the Pact contract tests that keep ``nextcloud-mcp-server``
+and the ``astrolabe`` Nextcloud app wire-compatible:
+
+- **Consumer** (this server -> astrolabe): ``test_astrolabe_credentials_consumer``
+  generates a pact for the background-sync credentials API that the
+  ``AstrolabeClient`` consumes.
+- **Provider** (astrolabe -> this server): ``test_mcp_provider_verification``
+  verifies the ``/api/v1/*`` HTTP API this server exposes against pacts that
+  the astrolabe app publishes to the broker.
+"""

tests/contract/conftest.py

@@ -0,0 +1,48 @@
+"""Fixtures shared by the Pact contract tests (ADR-029).
+
+The consumer tests build a fresh ``Pact`` per test and merge their interaction
+into a single pact file under ``tests/contract/pacts/``. A session-scoped
+autouse fixture wipes that directory once at the start of a run so merged pacts
+never accumulate stale interactions across runs (``write_file(overwrite=False)``
+merges into whatever is already on disk).
+"""
+
+import shutil
+from pathlib import Path
+
+import pytest
+from pact import Pact
+
+# Pact participant names. These MUST match the names used on the astrolabe side
+# and in the broker, so keep them in sync with the astrolabe repo's pact tests.
+CONSUMER = "nextcloud-mcp-server"
+PROVIDER = "astrolabe"
+
+PACT_DIR = Path(__file__).parent / "pacts"
+
+
+@pytest.fixture(scope="session", autouse=True)
+def _clean_pact_dir():
+    """Start each session from an empty pacts directory."""
+    if PACT_DIR.exists():
+        shutil.rmtree(PACT_DIR)
+    PACT_DIR.mkdir(parents=True, exist_ok=True)
+    yield
+
+
+@pytest.fixture
+def pact_dir() -> Path:
+    """Directory the generated pact files are written to."""
+    return PACT_DIR
+
+
+@pytest.fixture
+def consumer_pact():
+    """A fresh Pact (consumer=nextcloud-mcp-server, provider=astrolabe).
+
+    The interaction added by each test is merged into the shared pact file on
+    teardown.
+    """
+    pact = Pact(CONSUMER, PROVIDER).with_specification("V4")
+    yield pact
+    pact.write_file(PACT_DIR, overwrite=False)

tests/contract/test_astrolabe_credentials_consumer.py

@@ -0,0 +1,102 @@
+"""Consumer contract: nextcloud-mcp-server -> astrolabe credentials status API.
+
+The MCP server checks a user's background-sync provisioning status via
+:meth:`AstrolabeClient.get_background_sync_status`, which calls astrolabe's
+admin credentials-metadata endpoint
+(``GET /apps/astrolabe/api/v1/background-sync/credentials/{user_id}``). That
+endpoint returns **presence/timestamps only — never the app password itself**
+(the password reaches the MCP server out-of-band, pushed by astrolabe to
+``POST /api/v1/users/{user_id}/app-password``).
+
+This pact pins the request shape and the two states the consumer branches on:
+
+- provisioned   -> ``has_background_access: true``,  ``sync_type: "app_password"``
+- unprovisioned -> ``has_background_access: false``, ``sync_type: null``
+
+The OAuth token fetch (:meth:`AstrolabeClient.get_access_token`) is stubbed so
+only the status call hits the Pact mock server.
+
+See ADR-029 for the overall contract-testing architecture.
+"""
+
+import pytest
+from pact import match
+
+from nextcloud_mcp_server.auth.astrolabe_client import AstrolabeClient
+
+pytestmark = pytest.mark.contract
+
+# Matches the ``Authorization: Bearer <token>`` header the client always sends.
+_BEARER = match.regex("Bearer test-token", regex=r"Bearer .+")
+
+
+async def test_status_reports_access_for_provisioned_user(consumer_pact, mocker):
+    """A provisioned user is reported as having background access."""
+    (
+        consumer_pact.upon_receiving(
+            "a request for a provisioned user's background-sync status"
+        )
+        .given("user alice has provisioned background-sync credentials")
+        .with_request("GET", "/apps/astrolabe/api/v1/background-sync/credentials/alice")
+        .with_header("Authorization", _BEARER)
+        .will_respond_with(200)
+        .with_body(
+            {
+                "success": True,
+                "user_id": "alice",
+                "has_background_access": True,
+                "sync_type": "app_password",
+                # Unix seconds (astrolabe BackgroundSyncCredentialStorage::getProvisionedAt),
+                # not an ISO string.
+                "provisioned_at": match.integer(1717000000),
+            },
+            content_type="application/json",
+        )
+    )
+
+    with consumer_pact.serve() as srv:
+        client = AstrolabeClient(
+            nextcloud_host=str(srv.url), client_id="mcp", client_secret="secret"
+        )
+        mocker.patch.object(client, "get_access_token", return_value="test-token")
+
+        status = await client.get_background_sync_status("alice")
+
+    assert status["has_access"] is True
+    assert status["credential_type"] == "app_password"
+    assert status["provisioned_at"] == 1717000000
+
+
+async def test_status_reports_no_access_for_unprovisioned_user(consumer_pact, mocker):
+    """An unprovisioned user is reported as having no background access."""
+    (
+        consumer_pact.upon_receiving(
+            "a request for an unprovisioned user's background-sync status"
+        )
+        .given("user bob has no background-sync credentials")
+        .with_request("GET", "/apps/astrolabe/api/v1/background-sync/credentials/bob")
+        .with_header("Authorization", _BEARER)
+        .will_respond_with(200)
+        .with_body(
+            {
+                "success": True,
+                "user_id": "bob",
+                "has_background_access": False,
+                "sync_type": None,
+                "provisioned_at": None,
+            },
+            content_type="application/json",
+        )
+    )
+
+    with consumer_pact.serve() as srv:
+        client = AstrolabeClient(
+            nextcloud_host=str(srv.url), client_id="mcp", client_secret="secret"
+        )
+        mocker.patch.object(client, "get_access_token", return_value="test-token")
+
+        status = await client.get_background_sync_status("bob")
+
+    assert status["has_access"] is False
+    assert status["credential_type"] is None
+    assert status["provisioned_at"] is None

tests/contract/test_mcp_provider_verification.py

@@ -0,0 +1,110 @@
+"""Provider verification: astrolabe -> nextcloud-mcp-server /api/v1 API.
+
+The astrolabe Nextcloud app consumes this server's ``/api/v1/*`` HTTP API
+(``lib/Service/McpServerClient.php``: ``search``, ``webhooks`` CRUD, ``apps``,
+``status``, ``vector-sync/status``, ``chunk-context``, ``pdf-preview``,
+``vector-viz/search``). This test plays the **provider** role: it pulls the
+pacts astrolabe published to the broker and replays each interaction against a
+running MCP server, failing if a response no longer matches the contract.
+
+It is **environment-gated** and skips unless a running provider and a pact
+source are configured, so it is a no-op in the consumer-only job and in local
+unit runs. Wire it into CI against the integration docker stack (see
+``.github/workflows/pact.yml``).
+
+Required environment:
+- ``PACT_PROVIDER_URL`` — base URL of the running MCP server to verify against
+  (e.g. ``http://localhost:8000``).
+- One pact source, either:
+  - ``PACT_BROKER`` (+ ``PACT_USERNAME`` / ``PACT_PASSWORD``) — verify against
+    pacts in the broker, or
+  - ``PACT_PROVIDER_PACT_DIR`` — verify against a local directory of pacts.
+
+Optional:
+- ``PACT_PROVIDER_VERSION`` — provider version (git SHA) to publish results under.
+- ``PACT_PROVIDER_BRANCH`` — provider branch for the published results.
+- ``PACT_PUBLISH_RESULTS=true`` — publish verification results to the broker.
+
+See ADR-029.
+"""
+
+import logging
+import os
+from collections.abc import Callable
+
+import pytest
+from pact import Verifier
+
+pytestmark = pytest.mark.contract
+
+logger = logging.getLogger(__name__)
+
+PROVIDER_NAME = "nextcloud-mcp-server"
+
+_PROVIDER_URL = os.environ.get("PACT_PROVIDER_URL")
+_BROKER_URL = os.environ.get("PACT_BROKER")
+_LOCAL_PACT_DIR = os.environ.get("PACT_PROVIDER_PACT_DIR")
+
+# Skip the whole module unless we have a provider to hit AND a pact source.
+pytestmark = [
+    pytest.mark.contract,
+    pytest.mark.skipif(
+        not _PROVIDER_URL or not (_BROKER_URL or _LOCAL_PACT_DIR),
+        reason=(
+            "Provider verification needs PACT_PROVIDER_URL and a pact source "
+            "(PACT_BROKER or PACT_PROVIDER_PACT_DIR). Skipped outside CI."
+        ),
+    ),
+]
+
+
+# Map astrolabe-side provider-state strings -> setup callables. astrolabe's
+# consumer pacts declare the ``given(...)`` provider states; add one handler per
+# state name here as those pacts are written (seeding webhooks DB, qdrant
+# fixtures, etc.). Keep the keys identical to the astrolabe ``given(...)``
+# strings. Unhandled states fall through to ``_dispatch_state`` which logs and
+# no-ops, so state-less interactions still verify.
+_PROVIDER_STATES: dict[str, Callable[[], None]] = {
+    # "a webhook is registered for user alice": _state_webhook_registered,
+    # "vector sync has indexed documents": _state_vector_sync_ran,
+    # "the search index returns a hit for 'budget'": _state_search_has_hit,
+}
+
+
+def _dispatch_state(state: str, **kwargs) -> None:
+    """Provider-state dispatcher passed to the verifier.
+
+    Looks up a registered handler by state name; logs and no-ops for unknown
+    states so contracts that don't require seeded state (``/api/v1/status``,
+    ``/api/v1/vector-sync/status``) verify without a handler.
+    """
+    handler = _PROVIDER_STATES.get(state)
+    if handler is None:
+        logger.warning("No provider-state handler registered for %r; no-op", state)
+        return
+    handler()
+
+
+def test_verify_astrolabe_consumer_pacts() -> None:
+    """Verify the MCP server honours every interaction astrolabe published."""
+    verifier = Verifier(PROVIDER_NAME).add_transport(url=_PROVIDER_URL)
+    verifier.state_handler(_dispatch_state, teardown=True)
+
+    if _BROKER_URL:
+        # Basic-auth creds accompany the broker URL (see module skipif).
+        username = os.environ["PACT_USERNAME"]
+        password = os.environ["PACT_PASSWORD"]
+        verifier.broker_source(_BROKER_URL, username=username, password=password)
+    else:
+        assert _LOCAL_PACT_DIR is not None  # guaranteed by module skipif
+        verifier.add_source(_LOCAL_PACT_DIR)
+
+    if os.environ.get("PACT_PUBLISH_RESULTS", "").lower() == "true":
+        version = os.environ.get("PACT_PROVIDER_VERSION", "dev")
+        verifier.set_publish_options(
+            version=version,
+            branch=os.environ.get("PACT_PROVIDER_BRANCH"),
+        )
+
+    # Raises (failing the test) if any interaction does not match.
+    verifier.verify()

uv.lock

@@ -2236,6 +2236,7 @@ dev = [
     { name = "commitizen" },
     { name = "datasets" },
     { name = "ipython" },
+    { name = "pact-python" },
     { name = "playwright" },
     { name = "procrastinate" },
     { name = "psycopg", extra = ["binary", "pool"] },
@@ -2299,6 +2300,7 @@ dev = [
     { name = "commitizen", specifier = ">=4.8.2" },
     { name = "datasets", specifier = ">=3.3.0" },
     { name = "ipython", specifier = ">=9.2.0" },
+    { name = "pact-python", specifier = ">=3.4.0" },
     { name = "playwright", specifier = ">=1.49.1" },
     { name = "procrastinate", specifier = ">=3.8" },
     { name = "psycopg", extras = ["binary", "pool"], specifier = ">=3.2" },
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 ]
 
+[[package]]
+name = "pact-python"
+version = "3.4.0"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "pact-python-ffi" },
+    { name = "typing-extensions", marker = "python_full_version < '3.13'" },
+    { name = "yarl" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/41/d0/0f7b44586c232e86383a6224eb9f6bfb511d2c9630b692312506a879ac40/pact_python-3.4.0.tar.gz", hash = "sha256:e4a500fa00e1fd586cecf473a74db1e604af5e1be97a312d88eced46c25395c0", size = 82088, upload-time = "2026-05-04T09:40:06.947Z" }
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+]
+
+[[package]]
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+source = { registry = "https://pypi.org/simple" }
+dependencies = [
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+]
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+
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 name = "pandas"
 version = "2.3.3"