The pluggable unit is an app, not an extension

.github/workflows/on-pull-request-backend.yml

@@ -61,7 +61,7 @@ jobs:
           python-version: "3.11"
       - run: uv sync --locked --dev
       - run: uv run ruff check backend
-      # The proof extension is a standalone distribution that depends on druks;
+      # The proof app is a standalone distribution that depends on druks;
       # it installs the way an author's would, so druks never depends on it.
       - run: uv pip install -e backend/tests/druks-field_notes
       # Hang defense is pytest-timeout (pyproject): 180s per test, thread

Dockerfile

@@ -53,4 +53,4 @@ ENV USER=druks LOGNAME=druks
 
 EXPOSE 8001
 ENTRYPOINT ["tini", "--"]
-CMD ["uvicorn", "druks.api.app:app", "--host", "127.0.0.1", "--port", "8001"]
+CMD ["uvicorn", "druks.api.server:app", "--host", "127.0.0.1", "--port", "8001"]

backend/druks/agents.py

@@ -10,12 +10,12 @@
 from dbos import DBOS, StepOptions
 from pydantic import BaseModel, ConfigDict
 
+from druks.apps.registry import agents
 from druks.database import db_session
 from druks.durable.activity import set_run_phase
 from druks.durable.engine import _step_engine, step_session
 from druks.durable.exceptions import WorkflowError
 from druks.durable.models import AgentCall, Artifact
-from druks.extensions.registry import agents
 from druks.harnesses.exceptions import HarnessError, Retry
 from druks.harnesses.models import HarnessConnection
 from druks.harnesses.registry import get_harness_for_model
@@ -102,10 +102,10 @@ class Agent:
     include_plugins: bool = True
     # ``id`` is the agent's durable key (settings, timeline, registry): the attribute
     # name it's declared as, or an explicit ``id=`` for a standalone agent (a test, a
-    # one-off). ``extension`` is the owning Extension's name, read from the class in
+    # one-off). ``app`` is the owning App's name, read from the class in
     # __set_name__ to group the settings UI — blank for a standalone agent (no owner).
     id: str = field(default="", compare=False)
-    extension: str = field(init=False, compare=False, default="")
+    app: str = field(init=False, compare=False, default="")
 
     def __post_init__(self) -> None:
         if self.id:  # an explicit id means a standalone agent — it registers itself now
@@ -115,7 +115,7 @@ def __set_name__(self, owner: type, attr: str) -> None:
         if self.id:  # explicit id: already registered in __post_init__
             return
         object.__setattr__(self, "id", attr)
-        object.__setattr__(self, "extension", owner.name)
+        object.__setattr__(self, "app", owner.name)
         agents.register(self)
 
     # The effective settings, resolved through the override store: per-agent
@@ -142,11 +142,11 @@ async def __call__(self, **context: object) -> Any:
         workflow_id comes from the workflow context, not the caller; everything
         else (repo, …) is prompt context."""
         if not self.id:
-            # Built loose — never assigned to an Extension, never given an explicit
+            # Built loose — never assigned to an App, never given an explicit
             # id — so its settings, its registry entry and the call it would record
             # all key on nothing.
             raise WorkflowError(
-                "an agent runs under its own id — declare it on an Extension, or "
+                "an agent runs under its own id — declare it on an App, or "
                 "pass id= for a standalone one"
             )
         workflow = current_workflow.get(None)

backend/druks/alembic_support.py

@@ -8,7 +8,7 @@
 
 def _render_item(type_, obj, autogen_context):
     # Render app TypeDecorators as their plain DDL type so migrations never
-    # import extension code. _UtcDateTime only changes read-side tz coercion
+    # import app code. _UtcDateTime only changes read-side tz coercion
     # (DDL is TIMESTAMPTZ); the encrypted columns store as LargeBinary (bytea).
     if type_ == "type" and obj.__class__.__name__ == "_UtcDateTime":
         return "sa.DateTime(timezone=True)"
@@ -19,7 +19,7 @@ def _render_item(type_, obj, autogen_context):
 
 def run_alembic_env(target_metadata=None) -> None:
     """Run the platform Alembic env against the target metadata. Core and every
-    installed extension share one ``env.py``; the runner selects the scope by setting
+    installed app share one ``env.py``; the runner selects the scope by setting
     ``target_metadata`` and ``version_table`` in ``config.attributes``. Metadata
     falls back to the full ``Base.metadata`` (core's own scope, e.g. core's raw
     autogenerate). ``include_object`` keeps autogenerate within the scope: a table
@@ -41,7 +41,7 @@ def include_object(obj, name, type_, reflected, compare_to):
         "render_item": _render_item,
         "include_object": include_object,
         # Each migration history tracks its head in its own version table, so an
-        # installed extension's independent history never reads (and chokes on) core's
+        # installed app's independent history never reads (and chokes on) core's
         # revision in the shared default ``alembic_version``.
         "version_table": config.attributes.get("version_table", "alembic_version"),
     }

backend/druks/api/schemas.py

@@ -28,7 +28,7 @@ class RetryRunResponse(BaseResponse):
 
 
 class OpenWorkflowResponse(BaseResponse):
-    extension: str
+    app: str
     state: RunState
     run: str = Field(description="What get_gate, cancel_run, and retry_run take.")
     latest_agent_call: str | None = Field(

backend/druks/api/app.py → backend/druks/api/server.py

@@ -18,15 +18,15 @@
 from druks.api.exceptions import AgentApiError
 from druks.api.runs import router as runs_router
 from druks.api.subjects import router as subjects_router
+from druks.apps.loader import iter_apps, load
+from druks.apps.routes import router as apps_router
 from druks.browser.exceptions import BrowserApiError
 from druks.browser.routes import router as browser_sessions_router
 from druks.core.templates import render_page
 from druks.database import configure_session, create_engine_from_url, db_session, session_scope
 from druks.durable.engine import init_dbos, launch, shutdown
 from druks.durable.exceptions import AgentCallNotFound
 from druks.events.routes import router as events_router
-from druks.extensions.loader import iter_extensions, load
-from druks.extensions.routes import router as extensions_router
 from druks.harnesses.routes import router as harness_connection_router
 from druks.mcp.catalog import load_mcp_catalog
 from druks.mcp.gateway import exceptions as gate_errors
@@ -82,14 +82,14 @@ async def lifespan(app: FastAPI) -> AsyncIterator[None]:
         # reach here — they drive DBOS through their own fixtures.
         init_dbos()
         launch()
-        # Each extension converges its own runtime state (e.g. schedules) here, after
-        # DBOS is live. A failing hook is logged, not fatal — one extension can't wedge boot.
-        for extension in iter_extensions():
+        # Each app converges its own runtime state (e.g. schedules) here, after
+        # DBOS is live. A failing hook is logged, not fatal — one app can't wedge boot.
+        for registered_app in iter_apps():
             try:
-                await extension.on_startup()
+                await registered_app.on_startup()
             except Exception:
                 logging.getLogger(__name__).exception(
-                    "extension %r on_startup failed", extension.name
+                    "app %r on_startup failed", registered_app.name
                 )
 
     try:
@@ -108,7 +108,7 @@ async def _release_db_session() -> AsyncIterator[None]:
     without committing, so this is the commit boundary. FastAPI runs this
     yield-dependency's teardown in the *same* asyncio task as the endpoint
     (the scoped_session is keyed by that task), so it acts on exactly the
-    session this request opened. Frontend responses (the SPA, an extension's
+    session this request opened. Frontend responses (the SPA, an app's
     dist/) run app dependencies too, so only touch the registry when the
     request actually opened a session — never open one just to commit nothing.
     """
@@ -248,8 +248,8 @@ async def _unhandled_exception_handler(
     )
 
 
-# Platform-core routers, mounted by hand at their own prefixes. Extension routers
-# (core, ship, usage, …) are discovered and mounted under /api/<extension> by load().
+# Platform-core routers, mounted by hand at their own prefixes. App routers
+# (core, ship, usage, …) are discovered and mounted under /api/<app> by load().
 # /api sits behind the identity gate except the identity/connection surface and
 # the health probe; /_external routes carry their own authentication. The
 # boundary test pins the split. The auth and harness-connection routers mount
@@ -265,7 +265,7 @@ async def _unhandled_exception_handler(
 app.include_router(harness_connection_router)
 app.include_router(browser_sessions_router)
 app.include_router(settings_router, dependencies=_identity_gate)
-app.include_router(extensions_router, dependencies=_identity_gate)
+app.include_router(apps_router, dependencies=_identity_gate)
 app.include_router(service_identities_router, dependencies=_identity_gate)
 app.include_router(oauth_router, dependencies=_identity_gate)
 app.include_router(skills_router, dependencies=_identity_gate)
@@ -279,8 +279,8 @@ async def _unhandled_exception_handler(
 load(app)
 
 # Tools derive from every route tagged "agent", so the endpoint composes
-# after load() — an extension's tagged routes join tools/list too.
-from druks.mcp.app import create_mcp_app  # noqa: E402
+# after load() — an app's tagged routes join tools/list too.
+from druks.mcp.server import create_mcp_app  # noqa: E402
 
 # A bare Route at exactly /mcp (a Mount would 307 the no-slash path); PATs
 # authenticate it, so it sits outside the identity gate.
@@ -320,17 +320,17 @@ async def mcp_not_found(path: str) -> None:
 
 
 def serve_spa(app: FastAPI, dist: Path = _SPA_DIST) -> None:
-    """Serve the platform's own dashboard the way an extension's ``dist/`` is
+    """Serve the platform's own dashboard the way an app's ``dist/`` is
     served — FastAPI's low-priority frontend routes, so every API path (and every
-    extension frontend, registered earlier) wins, and unknown paths fall back to
+    app frontend, registered earlier) wins, and unknown paths fall back to
     index.html for client-side routing. A bare pip install ships no SPA build;
     then the API serves JSON only."""
     if (dist / "index.html").is_file():
         app.frontend("/", directory=dist)
 
 
 class SpaCacheControl:
-    """Cache policy for the served frontends (the SPA, an extension's dist/) —
+    """Cache policy for the served frontends (the SPA, an app's dist/) —
     it lives with their server, not the edge proxy. Vite fingerprints every
     asset filename (index-<hash>.js), so an asset URL's content never changes:
     cache it forever. index.html is the un-fingerprinted entry point that
@@ -350,7 +350,7 @@ async def __call__(self, scope: Any, receive: Any, send: Any) -> None:
             await self.app(scope, receive, send)
             return
         path = scope["path"]
-        # The SPA's /assets/* and an extension's /app/<name>/assets/* — never
+        # The SPA's /assets/* and an app's /app/<name>/assets/* — never
         # /api/*, whose responses must not inherit frontend cache policy.
         fingerprinted = path.startswith("/assets/") or (
             path.startswith("/app/") and "/assets/" in path

backend/druks/api/subjects.py

@@ -35,7 +35,7 @@ async def list_open_subjects() -> OpenSubjectsResponse:
                     failure = failure.encode()[-_FAILURE_TAIL_BYTES:].decode(errors="ignore")
                 workflows.append(
                     OpenWorkflowResponse(
-                        extension=row.kind.partition(".")[0],
+                        app=row.kind.partition(".")[0],
                         state=RunState(row.state),
                         run=row.run_id,
                         latest_agent_call=row.latest_call_id,

backend/druks/apps/__init__.py

@@ -0,0 +1,3 @@
+from .base import App, AppSettings, Secret
+
+__all__ = ["App", "AppSettings", "Secret"]