diff --git a/README.md b/README.md
index 08f917f..2038a95 100644
--- a/README.md
+++ b/README.md
@@ -29,8 +29,8 @@ The package manager records the checkout in `~/.prime/agent/settings.json`. Keep
 ## configuration
 
 ```bash
-export PRIME_COMMITMENT_OBSERVER_PROVIDER=google
-export PRIME_COMMITMENT_OBSERVER_MODEL=gemini-3.1-flash-lite
+export PRIME_COMMITMENT_OBSERVER_PROVIDER=deepseek
+export PRIME_COMMITMENT_OBSERVER_MODEL=deepseek-v4-flash
 export PRIME_COMMITMENT_OBSERVER_TIMEOUT_MS=60000
 ```
 
diff --git a/src/observer.ts b/src/observer.ts
index 35b9827..c3f9bd3 100644
--- a/src/observer.ts
+++ b/src/observer.ts
@@ -23,8 +23,8 @@ export type ObserverResult =
 
 export function configFromEnv(env: NodeJS.ProcessEnv = process.env): ObserverConfig {
 	return {
-		provider: env.PRIME_COMMITMENT_OBSERVER_PROVIDER ?? "google",
-		modelId: env.PRIME_COMMITMENT_OBSERVER_MODEL ?? "gemini-3.1-flash-lite",
+		provider: env.PRIME_COMMITMENT_OBSERVER_PROVIDER ?? "deepseek",
+		modelId: env.PRIME_COMMITMENT_OBSERVER_MODEL ?? "deepseek-v4-flash",
 		apiKey: env.PRIME_COMMITMENT_OBSERVER_API_KEY,
 		baseUrl: env.PRIME_COMMITMENT_OBSERVER_BASE_URL,
 		temperature: env.PRIME_COMMITMENT_OBSERVER_TEMPERATURE
diff --git a/src/prompt.ts b/src/prompt.ts
index cedd611..0f2c48c 100644
--- a/src/prompt.ts
+++ b/src/prompt.ts
@@ -1,6 +1,8 @@
 export const OBSERVER_SYSTEM_PROMPT = `You maintain a lightweight ledger of unfinished user requests after one completed agent turn.
 
-Return JSON matching the supplied schema.
+Return exactly one JSON object with this shape and no Markdown:
+{"existing":[{"id":"...","canonicalRequest":"...","status":"..."}],"additions":[{"canonicalRequest":"...","status":"..."}]}
+Existing entries always include id. Addition entries never include id.
 
 Rules:
 - Return every existing thread exactly once in existing, with its unchanged id.
diff --git a/test/logic.test.ts b/test/logic.test.ts
index 6d91b7f..41b8b27 100644
--- a/test/logic.test.ts
+++ b/test/logic.test.ts
@@ -159,6 +159,7 @@ test("pending context escapes user-authored markup", () => {
 
 test("prompt has one coherent completion contract", () => {
 	assert.match(OBSERVER_SYSTEM_PROMPT, /Use done when/);
+	assert.match(OBSERVER_SYSTEM_PROMPT, /Addition entries never include id/);
 	assert.doesNotMatch(OBSERVER_SYSTEM_PROMPT, /Never emit done|evidenceActionIds|required validation/);
 });