diff --git a/frontend/src/shell/SteerInput.test.tsx b/frontend/src/shell/SteerInput.test.tsx
index 86faebbd..e8974f0c 100644
--- a/frontend/src/shell/SteerInput.test.tsx
+++ b/frontend/src/shell/SteerInput.test.tsx
@@ -181,6 +181,56 @@ test("footer limits model choices to the selected workspace policy", async () =>
   await waitFor(() => expect(selector).not.toHaveTextContent("DeepSeek V4 Pro"));
 });
 
+test("switching workspaces replaces an out-of-policy model before session creation", async () => {
+  let body: unknown;
+  localStorage.setItem("thothii.workspace-registry.v1.preferences", JSON.stringify({
+    workspaceId: "research", provider: "deepseek", model: "deepseek-v4-pro", thinking: "medium",
+  }));
+  const revision = (id: string) => ({
+    id, commit: "a".repeat(40), blob: "b".repeat(40), snapshotPath: "/snapshot", state: "operational" as const,
+  });
+  server.use(
+    http.get("http://localhost:8787/settings", () => HttpResponse.json({
+      workspace: "research", provider: "deepseek", model: "deepseek-v4-pro", thinking: "medium",
+    })),
+    http.get("http://localhost:8787/workspaces", () => HttpResponse.json([
+      { id: "research", name: "research", file: "research.yaml", displayName: "Research", revision: revision("research") },
+      { id: "psd-clinical", name: "psd-clinical", file: "psd-clinical.yaml", displayName: "PSD Clinical", revision: revision("psd-clinical") },
+    ])),
+    http.get("http://localhost:8787/workspaces/research", () => HttpResponse.json({
+      workspace: { workspace: { id: "research" }, llm_policy: { allowed: ["deepseek/deepseek-v4-pro"] } },
+      revision: revision("research"),
+    })),
+    http.get("http://localhost:8787/workspaces/psd-clinical", () => HttpResponse.json({
+      workspace: { workspace: { id: "psd-clinical" }, llm_policy: { default: "zai/glm-5.2", allowed: ["zai/glm-5.2"] } },
+      revision: revision("psd-clinical"),
+    })),
+    http.get("http://localhost:8787/models", () => HttpResponse.json({ models: [
+      { provider: "zai", id: "glm-5.2", name: "GLM-5.2", reasoning: true },
+      { provider: "deepseek", id: "deepseek-v4-pro", name: "DeepSeek V4 Pro", reasoning: true },
+    ] })),
+    http.post("http://localhost:8787/sessions", async ({ request }) => {
+      body = await request.json();
+      return HttpResponse.json({ id: "s1" });
+    }),
+  );
+  const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
+  render(<QueryClientProvider client={client}><ComposerFooter /><SteerInput sessionId={null} /></QueryClientProvider>);
+
+  const workspaceSelector = await screen.findByRole("combobox", { name: "Workspace" });
+  await waitFor(() => expect(workspaceSelector).toHaveTextContent("psd-clinical"));
+  await userEvent.selectOptions(workspaceSelector, "psd-clinical");
+  await waitFor(() => expect(screen.getByRole("combobox", { name: "Model" })).toHaveValue("glm-5.2"));
+  expect(screen.getByRole("combobox", { name: "Model" })).not.toHaveTextContent("DeepSeek V4 Pro");
+
+  await userEvent.type(screen.getByRole("textbox", { name: /new question/i }), "q");
+  await userEvent.click(screen.getByRole("button", { name: /send/i }));
+
+  await waitFor(() => expect(body).toEqual({
+    question: "q", workspaceId: "psd-clinical", provider: "zai", model: "glm-5.2", thinking: "medium",
+  }));
+});
+
 test("pulses the stop dot only while the harness is working", () => {
   const { rerender } = render(<SteerInput sessionId="s1" working />);
   const dot = () =>
diff --git a/frontend/src/shell/SteerInput.tsx b/frontend/src/shell/SteerInput.tsx
index a503b7b8..74c95e9d 100644
--- a/frontend/src/shell/SteerInput.tsx
+++ b/frontend/src/shell/SteerInput.tsx
@@ -189,6 +189,27 @@ export function ComposerFooter() {
     ? models.filter((candidate) => allowedModels.includes(`${candidate.provider}/${candidate.id}`))
     : models;
 
+  useEffect(() => {
+    if (!allowedModels?.length) return;
+    const selected = preferences.provider && preferences.model
+      ? `${preferences.provider}/${preferences.model}`
+      : undefined;
+    if (selected && allowedModels.some((allowed) => allowed === selected)) return;
+    const replacement = workspaceRecord?.workspace.llm_policy.default
+      && allowedModels.includes(workspaceRecord.workspace.llm_policy.default)
+      ? workspaceRecord.workspace.llm_policy.default
+      : allowedModels[0];
+    const separator = replacement.indexOf("/");
+    if (separator <= 0 || separator === replacement.length - 1) return;
+    const next = {
+      ...preferences,
+      provider: replacement.slice(0, separator),
+      model: replacement.slice(separator + 1),
+    };
+    workspacePreferences.save(next);
+    setPreferences(next);
+  }, [allowedModels, preferences, workspaceRecord]);
+
   function update(patch: WorkspacePreference) {
     const next = workspacePreferences.save({ ...preferences, ...patch });
     setPreferences(next);
@@ -200,6 +221,7 @@ export function ComposerFooter() {
   }
 
   const knownModel = policyModels.some((m) => m.id === model);
+  const showModelFallback = !allowedModels && !knownModel;
   const contextPct = tokenUsage && tokenUsage.contextWindow > 0
     ? tokenUsage.totalTokens / tokenUsage.contextWindow
     : 0;
@@ -232,7 +254,7 @@ export function ComposerFooter() {
             <option value={model}>{model || "— model —"}</option>
           ) : (
             <>
-              {!knownModel && <option value={model}>{model || "— model —"}</option>}
+              {showModelFallback && <option value={model}>{model || "— model —"}</option>}
               {policyModels.map((m) => (
                 <option key={`${m.provider}/${m.id}`} value={m.id}>
                   {m.name}
diff --git a/frontend/src/workspaces/drafts.test.ts b/frontend/src/workspaces/drafts.test.ts
index a8fe0c8d..6cdf0980 100644
--- a/frontend/src/workspaces/drafts.test.ts
+++ b/frontend/src/workspaces/drafts.test.ts
@@ -1,4 +1,4 @@
-import { expect, test } from "vitest";
+import { beforeEach, expect, test } from "vitest";
 import type { CanonicalWorkspace } from "../api/workspaces";
 import { workspaceDrafts, workspacePreferences } from "./drafts";
 
@@ -42,9 +42,10 @@ test("reloads a canonical workspace draft and discards it by workspace ID", () =
   expect(workspaceDrafts.load("psd-clinical")).toBeUndefined();
 });
 
-test("keeps canonical diagnostic configuration but never stores unknown draft fields", () => {
+test("keeps valid canonical diagnostic configuration", () => {
   const configured = {
     ...workspace,
+    dwh: { ...workspace.dwh, supported_transports: ["postgres_direct", "rest_api"] },
     diagnostics: {
       dwh_rest: {
         method: "POST",
@@ -53,8 +54,7 @@ test("keeps canonical diagnostic configuration but never stores unknown draft fi
         response: { database: "database", schema: "schema" },
       },
     },
-    secret: "must-not-be-persisted",
-  } as CanonicalWorkspace & { secret: string };
+  } satisfies CanonicalWorkspace;
   workspaceDrafts.save({
     workspaceId: "psd-clinical",
     baseCommit: "a".repeat(40),
@@ -63,5 +63,49 @@ test("keeps canonical diagnostic configuration but never stores unknown draft fi
   });
 
   expect(workspaceDrafts.load("psd-clinical")?.workspace.diagnostics).toEqual(configured.diagnostics);
-  expect(localStorage.getItem("thothii.workspace-registry.v1.draft.psd-clinical")).not.toContain("must-not-be-persisted");
+});
+
+beforeEach(() => localStorage.clear());
+
+test.each([
+  ["an unsupported schema version", { ...workspace, workspace: { ...workspace.workspace, schema_version: 1 } }],
+  ["an invalid DWH engine", { ...workspace, dwh: { ...workspace.dwh, engine: "mysql" } }],
+  ["a diagnostic path with a query", {
+    ...workspace,
+    diagnostics: {
+      dwh_rest: {
+        method: "POST", path: "/rpc/ping?token=secret", auth: "bearer",
+        response: { database: "database", schema: "schema" },
+      },
+    },
+  }],
+  ["a diagnostic path with a fragment", {
+    ...workspace,
+    diagnostics: {
+      dwh_rest: {
+        method: "POST", path: "/rpc/ping#token", auth: "bearer",
+        response: { database: "database", schema: "schema" },
+      },
+    },
+  }],
+  ["a diagnostic path outside the declared origin", {
+    ...workspace,
+    diagnostics: {
+      dwh_rest: {
+        method: "POST", path: "https://outside.example/rpc/ping", auth: "bearer",
+        response: { database: "database", schema: "schema" },
+      },
+    },
+  }],
+  ["an unknown secret field", { ...workspace, secret: "must-not-be-persisted" }],
+])("rejects a draft with %s", (_reason, invalidWorkspace) => {
+  workspaceDrafts.save({
+    workspaceId: "psd-clinical",
+    baseCommit: "a".repeat(40),
+    workspace: invalidWorkspace as CanonicalWorkspace,
+    updatedAt: "2026-08-04T10:00:00.000Z",
+  });
+
+  expect(workspaceDrafts.load("psd-clinical")).toBeUndefined();
+  expect(localStorage.getItem("thothii.workspace-registry.v1.draft.psd-clinical")).toBeNull();
 });
diff --git a/frontend/src/workspaces/drafts.ts b/frontend/src/workspaces/drafts.ts
index dd10d768..a349ef29 100644
--- a/frontend/src/workspaces/drafts.ts
+++ b/frontend/src/workspaces/drafts.ts
@@ -22,133 +22,216 @@ function record(value: unknown): Record<string, unknown> | undefined {
     : undefined;
 }
 
-function copyRequest(value: unknown): RestDiagnosticRequest | undefined {
+function exactRecord(value: unknown, keys: readonly string[]): Record<string, unknown> | undefined {
   const source = record(value);
-  if (
-    !source
-    || (source.method !== "GET" && source.method !== "POST")
-    || typeof source.path !== "string"
-    || (source.auth !== "none" && source.auth !== "bearer" && source.auth !== "x-api-key")
-  ) return undefined;
-  return { method: source.method, path: source.path, auth: source.auth };
+  return source && Object.keys(source).every((key) => keys.includes(key)) ? source : undefined;
+}
+
+function text(value: unknown): string | undefined {
+  return typeof value === "string" && value.trim().length > 0 ? value.trim() : undefined;
+}
+
+function identifier(value: unknown): string | undefined {
+  return typeof value === "string" && /^[A-Za-z_][A-Za-z0-9_]*$/.test(value) ? value : undefined;
+}
+
+function workspaceId(value: unknown): string | undefined {
+  return typeof value === "string" && /^[a-z][a-z0-9-]{2,62}$/.test(value) ? value : undefined;
+}
+
+function modelReference(value: unknown): `${string}/${string}` | undefined {
+  return typeof value === "string" && /^[^/\s]+\/[^/\s]+$/.test(value) ? value as `${string}/${string}` : undefined;
+}
+
+function positiveInteger(value: unknown, max = Number.MAX_SAFE_INTEGER): number | undefined {
+  return typeof value === "number" && Number.isInteger(value) && value > 0 && value <= max ? value : undefined;
+}
+
+function oneOf<T extends string>(value: unknown, choices: readonly T[]): T | undefined {
+  return typeof value === "string" && choices.includes(value as T) ? value as T : undefined;
+}
+
+function uniqueChoices<T extends string>(value: unknown, choices: readonly T[]): T[] | undefined {
+  if (!Array.isArray(value) || value.length === 0) return undefined;
+  const result: T[] = [];
+  for (const item of value) {
+    const choice = oneOf(item, choices);
+    if (!choice || result.includes(choice)) return undefined;
+    result.push(choice);
+  }
+  return result;
+}
+
+function uniqueModels(value: unknown): `${string}/${string}`[] | undefined {
+  if (!Array.isArray(value) || value.length === 0) return undefined;
+  const result: `${string}/${string}`[] = [];
+  for (const item of value) {
+    const model = modelReference(item);
+    if (!model || result.includes(model)) return undefined;
+    result.push(model);
+  }
+  return result;
+}
+
+function originRelativePath(value: unknown): string | undefined {
+  return typeof value === "string" && /^\/(?!\/)[^\\\u0000-\u001F\u007F?#]*$/.test(value) && !/%5c/i.test(value)
+    ? value
+    : undefined;
+}
+
+function copyRequest(value: unknown, extraKeys: readonly string[] = []): RestDiagnosticRequest | undefined {
+  const source = exactRecord(value, ["method", "path", "auth", ...extraKeys]);
+  const method = oneOf(source?.method, ["GET", "POST"] as const);
+  const path = originRelativePath(source?.path);
+  const auth = oneOf(source?.auth, ["none", "bearer", "x-api-key"] as const);
+  return method && path && auth ? { method, path, auth } : undefined;
 }
 
 function copyDiagnostics(value: unknown): CanonicalDiagnostics | undefined {
-  const source = record(value);
+  const source = exactRecord(value, ["dwh_rest", "vector_rest", "embedding"]);
   if (!source) return undefined;
   const diagnostics: CanonicalDiagnostics = {};
   if (source.dwh_rest !== undefined) {
-    const request = copyRequest(source.dwh_rest);
-    const response = record(record(source.dwh_rest)?.response);
-    if (!request || !response || typeof response.database !== "string" || typeof response.schema !== "string") return undefined;
-    diagnostics.dwh_rest = { ...request, response: { database: response.database, schema: response.schema } };
+    const request = copyRequest(source.dwh_rest, ["response"]);
+    const raw = exactRecord(source.dwh_rest, ["method", "path", "auth", "response"]);
+    const response = exactRecord(raw?.response, ["database", "schema"]);
+    const database = identifier(response?.database);
+    const schema = identifier(response?.schema);
+    if (!request || !database || !schema) return undefined;
+    diagnostics.dwh_rest = { ...request, response: { database, schema } };
   }
   if (source.vector_rest !== undefined) {
-    const vector = record(source.vector_rest);
-    const request = copyRequest(vector?.metadata);
-    const response = record(record(vector?.metadata)?.response);
-    if (!vector || !request || !response || typeof response.collection !== "string" || typeof response.dimensions !== "string" || typeof response.distance !== "string") return undefined;
-    const metadata = { ...request, response: { collection: response.collection, dimensions: response.dimensions, distance: response.distance } };
+    const vector = exactRecord(source.vector_rest, ["metadata", "reversible_probe"]);
+    const request = copyRequest(vector?.metadata, ["response"]);
+    const rawMetadata = exactRecord(vector?.metadata, ["method", "path", "auth", "response"]);
+    const response = exactRecord(rawMetadata?.response, ["collection", "dimensions", "distance"]);
+    const collection = identifier(response?.collection);
+    const dimensions = identifier(response?.dimensions);
+    const distance = identifier(response?.distance);
+    if (!vector || !request || !collection || !dimensions || !distance) return undefined;
+    const metadata = { ...request, response: { collection, dimensions, distance } };
     let reversibleProbe: NonNullable<CanonicalDiagnostics["vector_rest"]>["reversible_probe"] | undefined;
     if (vector.reversible_probe !== undefined) {
-      const probe = copyRequest(vector.reversible_probe);
-      const probeResponse = record(record(vector.reversible_probe)?.response);
-      if (!probe || probe.method !== "POST" || probe.auth === "none" || !probeResponse || typeof probeResponse.operation !== "string") return undefined;
+      const probe = copyRequest(vector.reversible_probe, ["response"]);
+      const rawProbe = exactRecord(vector.reversible_probe, ["method", "path", "auth", "response"]);
+      const probeResponse = exactRecord(rawProbe?.response, ["operation"]);
+      const operation = identifier(probeResponse?.operation);
+      if (!probe || probe.method !== "POST" || probe.auth === "none" || !operation) return undefined;
       reversibleProbe = {
         method: "POST",
         path: probe.path,
         auth: probe.auth as "bearer" | "x-api-key",
-        response: { operation: probeResponse.operation },
+        response: { operation },
       };
     }
     diagnostics.vector_rest = { metadata, ...(reversibleProbe ? { reversible_probe: reversibleProbe } : {}) };
   }
   if (source.embedding !== undefined) {
-    const request = copyRequest(source.embedding);
-    const response = record(record(source.embedding)?.response);
-    if (!request || !response || typeof response.model !== "string" || typeof response.dimensions !== "string") return undefined;
-    diagnostics.embedding = { ...request, response: { model: response.model, dimensions: response.dimensions } };
+    const request = copyRequest(source.embedding, ["response"]);
+    const raw = exactRecord(source.embedding, ["method", "path", "auth", "response"]);
+    const response = exactRecord(raw?.response, ["model", "dimensions"]);
+    const model = identifier(response?.model);
+    const dimensions = identifier(response?.dimensions);
+    if (!request || !model || !dimensions) return undefined;
+    diagnostics.embedding = { ...request, response: { model, dimensions } };
   }
   return diagnostics;
 }
 
 function copyWorkspace(value: unknown): CanonicalWorkspace | undefined {
-  const source = record(value);
-  const metadata = record(source?.workspace);
-  const dwh = record(source?.dwh);
-  const semanticIndex = record(source?.semantic_index);
-  const vectorStore = record(semanticIndex?.vector_store);
-  const embedding = record(semanticIndex?.embedding);
-  const policy = record(source?.llm_policy);
+  const source = exactRecord(value, ["workspace", "dwh", "semantic_index", "llm_policy", "diagnostics"]);
+  const metadata = exactRecord(source?.workspace, ["schema_version", "id", "name", "description", "language"]);
+  const dwh = exactRecord(source?.dwh, ["engine", "database", "schema", "port", "timeout_ms", "supported_transports"]);
+  const semanticIndex = exactRecord(source?.semantic_index, ["vector_store", "vector_writer", "embedding"]);
+  const vectorStore = exactRecord(semanticIndex?.vector_store, ["engine", "database", "schema", "collection", "dimensions", "distance", "port", "timeout_ms", "supported_transports"]);
+  const embedding = exactRecord(semanticIndex?.embedding, ["provider", "model", "dimensions", "timeout_ms"]);
+  const policy = exactRecord(source?.llm_policy, ["default", "allowed"]);
   const diagnostics = source?.diagnostics === undefined ? undefined : copyDiagnostics(source.diagnostics);
   if (!metadata || !dwh || !semanticIndex || !vectorStore || !embedding || !policy) return undefined;
+  const id = workspaceId(metadata.id);
+  const name = text(metadata.name);
+  const language = oneOf(metadata.language, ["en", "it"] as const);
+  const description = metadata.description === undefined ? undefined : text(metadata.description);
+  const database = identifier(dwh.database);
+  const schema = identifier(dwh.schema);
+  const dwhPort = dwh.port === undefined ? undefined : positiveInteger(dwh.port, 65_535);
+  const dwhTimeout = dwh.timeout_ms === undefined ? undefined : positiveInteger(dwh.timeout_ms);
+  const dwhTransports = uniqueChoices(dwh.supported_transports, ["postgres_direct", "rest_api", "ssh_tunnel"] as const);
+  const vectorDatabase = identifier(vectorStore.database);
+  const vectorSchema = identifier(vectorStore.schema);
+  const collection = identifier(vectorStore.collection);
+  const vectorDimensions = positiveInteger(vectorStore.dimensions, 32_768);
+  const distance = oneOf(vectorStore.distance, ["cosine", "l2", "inner_product"] as const);
+  const vectorPort = vectorStore.port === undefined ? undefined : positiveInteger(vectorStore.port, 65_535);
+  const vectorTimeout = vectorStore.timeout_ms === undefined ? undefined : positiveInteger(vectorStore.timeout_ms);
+  const vectorTransports = uniqueChoices(vectorStore.supported_transports, ["pgvector_direct", "rest_api", "ssh_tunnel"] as const);
+  const embeddingProvider = oneOf(embedding.provider, ["ollama_compatible", "openai_compatible"] as const);
+  const embeddingModel = text(embedding.model);
+  const embeddingDimensions = positiveInteger(embedding.dimensions, 32_768);
+  const embeddingTimeout = embedding.timeout_ms === undefined ? undefined : positiveInteger(embedding.timeout_ms);
+  const allowedModels = uniqueModels(policy.allowed);
+  const defaultModel = policy.default === undefined ? undefined : modelReference(policy.default);
   if (
-    typeof metadata.schema_version !== "number" || typeof metadata.id !== "string" || typeof metadata.name !== "string"
-    || typeof metadata.language !== "string" || typeof dwh.database !== "string" || typeof dwh.schema !== "string"
-    || typeof vectorStore.database !== "string" || typeof vectorStore.schema !== "string"
-    || typeof vectorStore.collection !== "string" || typeof vectorStore.dimensions !== "number"
-    || typeof embedding.model !== "string" || typeof embedding.dimensions !== "number"
-    || !Array.isArray(dwh.supported_transports) || !Array.isArray(vectorStore.supported_transports) || !Array.isArray(policy.allowed)
+    metadata.schema_version !== 2 || !id || !name || !language || (metadata.description !== undefined && !description)
+    || dwh.engine !== "postgres" || !database || !schema || (dwh.port !== undefined && !dwhPort) || (dwh.timeout_ms !== undefined && !dwhTimeout) || !dwhTransports
+    || vectorStore.engine !== "pgvector" || !vectorDatabase || !vectorSchema || !collection || !vectorDimensions || !distance || (vectorStore.port !== undefined && !vectorPort) || (vectorStore.timeout_ms !== undefined && !vectorTimeout) || !vectorTransports
+    || !embeddingProvider || !embeddingModel || !embeddingDimensions || (embedding.timeout_ms !== undefined && !embeddingTimeout) || !allowedModels
+    || (defaultModel !== undefined && !allowedModels.includes(defaultModel)) || vectorDimensions !== embeddingDimensions
+    || (semanticIndex.vector_writer !== undefined && !exactRecord(semanticIndex.vector_writer, []))
   ) return undefined;
   if (source?.diagnostics !== undefined && !diagnostics) return undefined;
+  if (diagnostics?.dwh_rest && !dwhTransports.includes("rest_api")) return undefined;
+  if (diagnostics?.vector_rest && !vectorTransports.includes("rest_api")) return undefined;
   return {
     workspace: {
-      schema_version: metadata.schema_version as 2,
-      id: metadata.id,
-      name: metadata.name,
-      ...(typeof metadata.description === "string" ? { description: metadata.description } : {}),
-      language: metadata.language as "en" | "it",
+      schema_version: 2,
+      id,
+      name,
+      ...(description ? { description } : {}),
+      language,
     },
     dwh: {
-      engine: dwh.engine as "postgres",
-      database: dwh.database,
-      schema: dwh.schema,
-      ...(typeof dwh.port === "number" ? { port: dwh.port } : {}),
-      ...(typeof dwh.timeout_ms === "number" ? { timeout_ms: dwh.timeout_ms } : {}),
-      supported_transports: dwh.supported_transports.filter((transport): transport is "postgres_direct" | "rest_api" | "ssh_tunnel" =>
-        transport === "postgres_direct" || transport === "rest_api" || transport === "ssh_tunnel"),
+      engine: "postgres", database, schema,
+      ...(dwhPort ? { port: dwhPort } : {}),
+      ...(dwhTimeout ? { timeout_ms: dwhTimeout } : {}),
+      supported_transports: dwhTransports,
     },
     semantic_index: {
       vector_store: {
-        engine: vectorStore.engine as "pgvector",
-        database: vectorStore.database,
-        schema: vectorStore.schema,
-        collection: vectorStore.collection,
-        dimensions: vectorStore.dimensions,
-        distance: vectorStore.distance as "cosine" | "l2" | "inner_product",
-        ...(typeof vectorStore.port === "number" ? { port: vectorStore.port } : {}),
-        ...(typeof vectorStore.timeout_ms === "number" ? { timeout_ms: vectorStore.timeout_ms } : {}),
-        supported_transports: vectorStore.supported_transports.filter((transport): transport is "pgvector_direct" | "rest_api" | "ssh_tunnel" =>
-          transport === "pgvector_direct" || transport === "rest_api" || transport === "ssh_tunnel"),
+        engine: "pgvector", database: vectorDatabase, schema: vectorSchema, collection, dimensions: vectorDimensions, distance,
+        ...(vectorPort ? { port: vectorPort } : {}),
+        ...(vectorTimeout ? { timeout_ms: vectorTimeout } : {}),
+        supported_transports: vectorTransports,
       },
-      ...(record(semanticIndex.vector_writer) ? { vector_writer: {} } : {}),
+      ...(semanticIndex.vector_writer ? { vector_writer: {} } : {}),
       embedding: {
-        provider: embedding.provider as "ollama_compatible" | "openai_compatible",
-        model: embedding.model,
-        dimensions: embedding.dimensions,
-        ...(typeof embedding.timeout_ms === "number" ? { timeout_ms: embedding.timeout_ms } : {}),
+        provider: embeddingProvider, model: embeddingModel, dimensions: embeddingDimensions,
+        ...(embeddingTimeout ? { timeout_ms: embeddingTimeout } : {}),
       },
     },
     llm_policy: {
-      ...(typeof policy.default === "string" ? { default: policy.default as `${string}/${string}` } : {}),
-      allowed: policy.allowed.filter((model): model is `${string}/${string}` => typeof model === "string"),
+      ...(defaultModel ? { default: defaultModel } : {}), allowed: allowedModels,
     },
     ...(diagnostics ? { diagnostics } : {}),
   };
 }
 
 function normalize(value: unknown): WorkspaceDraft | undefined {
-  const source = record(value);
+  const source = exactRecord(value, ["workspaceId", "baseCommit", "baseBlob", "workspace", "updatedAt"]);
   const workspace = copyWorkspace(source?.workspace);
-  if (!source || !workspace || typeof source.workspaceId !== "string" || typeof source.baseCommit !== "string" || typeof source.updatedAt !== "string") {
+  const id = workspaceId(source?.workspaceId);
+  const baseCommit = typeof source?.baseCommit === "string" && /^[0-9a-f]{40}$/.test(source.baseCommit) ? source.baseCommit : undefined;
+  const baseBlob = source?.baseBlob === undefined ? undefined : typeof source.baseBlob === "string" && /^[0-9a-f]{40}$/.test(source.baseBlob) ? source.baseBlob : undefined;
+  const updatedAt = typeof source?.updatedAt === "string" && Number.isFinite(Date.parse(source.updatedAt)) ? source.updatedAt : undefined;
+  if (!source || !workspace || !id || id !== workspace.workspace.id || !baseCommit || (source.baseBlob !== undefined && !baseBlob) || !updatedAt) {
     return undefined;
   }
   return {
-    workspaceId: source.workspaceId,
-    baseCommit: source.baseCommit,
-    ...(typeof source.baseBlob === "string" ? { baseBlob: source.baseBlob } : {}),
+    workspaceId: id,
+    baseCommit,
+    ...(baseBlob ? { baseBlob } : {}),
     workspace,
-    updatedAt: source.updatedAt,
+    updatedAt,
   };
 }