feat: unify installation model catalog

backend/src/routes/sessions.ts

@@ -6,12 +6,13 @@ import type { Settings } from "../settings/settings-store.js";
 import { getPrincipal } from "../auth/auth.js";
 import type { PrincipalContext } from "../auth/principal.js";
 import type { ReadinessManager } from "../runtime/readiness-manager.js";
-import type { ListModelsFn } from "./meta.js";
+import type { ListModelsFn } from "../pi/list-models.js";
 import type { WorkspaceRegistry } from "../workspaces/registry.js";
 import { validateOperationalWorkspace, type WorkspaceDescriptor } from "../workspaces/schema.js";
 import type { MaintenanceBarrier } from "../runtime/maintenance-gate.js";
 import { hasPermission, isPrincipalContext, requirePermission } from "../auth/authorization.js";
 import type { EffectiveRelationshipSnapshotProvider } from "../catalog/effective-relationship-snapshot.js";
+import { splitCanonicalModelId, type RuntimeModelCatalog } from "../models/runtime-model-catalog.js";
 
 const BOOTSTRAP_FAILURE_MESSAGE =
   "Session startup failed. Check configuration and connectivity, then Resume the session.";
@@ -43,6 +44,7 @@ export function sessionRoutes(
     maintenanceBarrier: MaintenanceBarrier;
     /** Optional only for narrow route-test stubs and installations without a Catalog database. */
     effectiveRelationships?: EffectiveRelationshipSnapshotProvider;
+    modelCatalog: RuntimeModelCatalog;
   },
 ) {
   const lifecycleTails = new Map<string, Promise<void>>();
@@ -358,7 +360,6 @@ export function sessionRoutes(
       let workspaceId: string | undefined;
       let workspaceRevision: string | undefined;
       let workspaceDescriptor: WorkspaceDescriptor | undefined;
-      let allowedModels: readonly string[] | undefined;
       if (requestedWorkspaceId) {
         try {
           const registry = d.workspaceRegistry as Partial<WorkspaceRegistry>;
@@ -378,7 +379,6 @@ export function sessionRoutes(
           workspaceId = resolved.revision.id;
           workspaceRevision = resolved.revision.commit;
           workspaceDescriptor = resolved.workspace;
-          allowedModels = resolved.workspace.llm_policy.allowed;
         } catch {
           return reply.code(409).send({
             error: WORKSPACE_REVISION_UNAVAILABLE_MESSAGE,
@@ -386,12 +386,17 @@ export function sessionRoutes(
           });
         }
       }
-      const provider = b.provider ?? s.provider;
-      const model = b.model ?? s.model;
+	  const requestedCanonical = b.provider && b.model ? `${b.provider}/${b.model}` : undefined;
+	  let selectedCanonical = requestedCanonical ?? d.modelCatalog.defaultSession;
+	  let modelWarning: string | undefined;
+	  if (selectedCanonical && d.modelCatalog.defaultSession && !d.modelCatalog.hasSession(selectedCanonical)) {
+	    selectedCanonical = d.modelCatalog.defaultSession;
+	    modelWarning = `Configured model ${requestedCanonical ?? "selection"} is unavailable; using ${selectedCanonical}.`;
+	  }
+	  const selected = selectedCanonical ? splitCanonicalModelId(selectedCanonical) : undefined;
+	  const provider = selected?.provider ?? b.provider;
+	  const model = selected?.model ?? b.model;
       const thinking = b.thinking ?? s.thinking;
-      if (allowedModels && provider && model && !allowedModels.includes(`${provider}/${model}`)) {
-        return reply.code(400).send({ error: "Selected model is not allowed by this workspace." });
-      }
       // A persisted session is resumable without keeping Pi alive. New work replaces every
       // runtime owned by this principal, while runtimes belonging to other users remain intact.
       // Optional chaining preserves the deliberately narrow manager stubs used by route tests.
@@ -490,7 +495,7 @@ export function sessionRoutes(
         ),
         () => d.mgr.start(id, rt, runtimeOptions),
       );
-      return { id };
+      return { id, ...(modelWarning ? { warning: modelWarning } : {}) };
     } finally {
       if (revisionLease && !manifestPersisted) {
         await revisionLease.abort().catch((error: unknown) => {
@@ -598,6 +603,10 @@ export function sessionRoutes(
         provider?: string; model?: string; thinking?: string;
         workspace_id?: string; workspace_revision?: string;
       };
+	  const savedCanonical = saved.provider && saved.model ? `${saved.provider}/${saved.model}` : "";
+	  if (d.modelCatalog.defaultSession && (!savedCanonical || !d.modelCatalog.hasSession(savedCanonical))) {
+	    return reply.code(503).send({ error: MODEL_UNAVAILABLE_MESSAGE, code: "model_unavailable" });
+	  }
       let workspaceConfigPath: string;
       let workspaceDescriptor: WorkspaceDescriptor | undefined;
       try {