Release 0.10.0: user-set passcodes (OTC stays as fallback)

After a successful OTC sign-in, a contributor can set a passcode
(4-20 characters, bcrypt-hashed) and use email + passcode for
subsequent sign-ins. OTC remains the structural fallback: five
consecutive failed verifies lock the passcode path for 15 minutes
(HTTP 423), and a forgotten passcode is recovered by requesting a
fresh code. Migration 015_passcode.sql adds four nullable columns
to the users table; existing rows pass through as OTC-only and can
opt into a passcode from a new Sign-in tab in /settings/notifications.
The /login surface is extended to a five-step flow (email → either
passcode or OTC code → optional post-OTC passcode offer → optional
set-passcode). SPEC corrections per §19.3 rule 2: §6 names the
three auth paths, §14.1 documents the stepped login flow, §17 lists
the four new /auth/passcode/* endpoints, §19.2 surfaces four new
candidates and refreshes the cross-refs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/main.py

@@ -24,6 +24,7 @@ from . import (
     email_otc,
     hygiene,
     otc,
+    passcode as passcode_mod,
     providers as providers_mod,
     webhooks,
 )
@@ -44,6 +45,15 @@ class OtcVerifyBody(BaseModel):
     code: str = Field(min_length=1, max_length=16)
 
 
+class PasscodeSetBody(BaseModel):
+    passcode: str = Field(min_length=1, max_length=64)
+
+
+class PasscodeVerifyBody(BaseModel):
+    email: str = Field(min_length=3, max_length=320)
+    passcode: str = Field(min_length=1, max_length=64)
+
+
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     config = load_config()
@@ -204,4 +214,72 @@ def _oauth_router(config) -> APIRouter:
             "needs_profile": needs_profile,
         }
 
+    # ---------------------------------------------------------------
+    # v0.10.0: user-set passcodes after OTC (§6.2, roadmap item #8).
+    #
+    # After a successful OTC sign-in, a contributor may set a passcode
+    # and use email + passcode for subsequent sign-ins. OTC remains the
+    # forgot-passcode fallback — a verify failure beyond 5 consecutive
+    # attempts locks the passcode path for 15 minutes; the OTC path is
+    # unaffected by the lockout.
+    # ---------------------------------------------------------------
+
+    @router.get("/auth/passcode/check")
+    async def passcode_check(email: str = ""):
+        """Does this email have a passcode set? Anonymous endpoint —
+        the Login.jsx flow calls this after the user types their email
+        to decide whether to render a passcode input or fall back to
+        OTC. We surface only the boolean; lockout state, the hash, and
+        the set-at stamp are not leaked here."""
+        status = passcode_mod.passcode_status(email)
+        return {"has_passcode": status.has_passcode}
+
+    @router.post("/auth/passcode/set")
+    async def passcode_set(body: PasscodeSetBody, request: Request):
+        """Set or replace the signed-in user's passcode. Requires an
+        active session (OTC- or passcode-authenticated)."""
+        user = auth.require_user(request)
+        try:
+            passcode_mod.set_passcode(user.user_id, body.passcode)
+        except passcode_mod.PasscodeValidationError as e:
+            raise HTTPException(422, str(e))
+        return {"ok": True}
+
+    @router.delete("/auth/passcode")
+    async def passcode_delete(request: Request):
+        """Remove the signed-in user's passcode. The user is back to
+        OTC-only on next sign-in."""
+        user = auth.require_user(request)
+        passcode_mod.clear_passcode(user.user_id)
+        return {"ok": True}
+
+    @router.post("/auth/passcode/verify")
+    async def passcode_verify(body: PasscodeVerifyBody, request: Request):
+        """Sign in with email + passcode. Returns the standard session
+        payload on success; HTTP 423 with `locked_until` when the
+        account is in the lockout window; HTTP 400 for every other
+        failure (the wrong-vs-unknown distinction is intentionally
+        collapsed so a probing client cannot enumerate emails)."""
+        result = passcode_mod.verify_passcode(body.email, body.passcode)
+        if result.reason == "locked":
+            raise HTTPException(
+                423,
+                {
+                    "detail": "Too many failed attempts; sign in with a one-time code instead",
+                    "locked_until": result.locked_until,
+                },
+            )
+        if not result.ok or result.user is None:
+            raise HTTPException(400, "Invalid passcode")
+        auth.store_session(request, result.user)
+        return {
+            "ok": True,
+            "user": {
+                "id": result.user.user_id,
+                "display_name": result.user.display_name,
+                "email": result.user.email,
+                "role": result.user.role,
+            },
+        }
+
     return router