feat: allow compaction model override via config (#38753)

Merged via squash.

Prepared head SHA: a3d6d6c845
Co-authored-by: starbuck100 <25417736+starbuck100@users.noreply.github.com>
Co-authored-by: jalehman <550978+jalehman@users.noreply.github.com>
Reviewed-by: @jalehman

src/agents/models-config.merge.test.ts

@@ -52,7 +52,10 @@ describe("models-config merge helpers", () => {
   it("merges explicit providers onto trimmed keys", () => {
     const merged = mergeProviders({
       explicit: {
-        " custom ": { api: "openai-responses", models: [] } as ProviderConfig,
+        " custom ": {
+          api: "openai-responses",
+          models: [] as ProviderConfig["models"],
+        } as ProviderConfig,
       },
     });
 

src/agents/pi-embedded-runner/compact.ts

@@ -271,8 +271,31 @@ export async function compactEmbeddedPiSessionDirect(
   const resolvedWorkspace = resolveUserPath(params.workspaceDir);
   const prevCwd = process.cwd();
 
-  const provider = (params.provider ?? DEFAULT_PROVIDER).trim() || DEFAULT_PROVIDER;
-  const modelId = (params.model ?? DEFAULT_MODEL).trim() || DEFAULT_MODEL;
+  // Resolve compaction model: prefer config override, then fall back to caller-supplied model
+  const compactionModelOverride = params.config?.agents?.defaults?.compaction?.model?.trim();
+  let provider: string;
+  let modelId: string;
+  // When switching provider via override, drop the primary auth profile to avoid
+  // sending the wrong credentials (e.g. OpenAI profile token to OpenRouter).
+  let authProfileId: string | undefined = params.authProfileId;
+  if (compactionModelOverride) {
+    const slashIdx = compactionModelOverride.indexOf("/");
+    if (slashIdx > 0) {
+      provider = compactionModelOverride.slice(0, slashIdx).trim();
+      modelId = compactionModelOverride.slice(slashIdx + 1).trim() || DEFAULT_MODEL;
+      // Provider changed — drop primary auth profile so getApiKeyForModel
+      // falls back to provider-based key resolution for the override model.
+      if (provider !== (params.provider ?? "").trim()) {
+        authProfileId = undefined;
+      }
+    } else {
+      provider = (params.provider ?? DEFAULT_PROVIDER).trim() || DEFAULT_PROVIDER;
+      modelId = compactionModelOverride;
+    }
+  } else {
+    provider = (params.provider ?? DEFAULT_PROVIDER).trim() || DEFAULT_PROVIDER;
+    modelId = (params.model ?? DEFAULT_MODEL).trim() || DEFAULT_MODEL;
+  }
   const fail = (reason: string): EmbeddedPiCompactResult => {
     log.warn(
       `[compaction-diag] end runId=${runId} sessionKey=${params.sessionKey ?? params.sessionId} ` +
@@ -302,7 +325,7 @@ export async function compactEmbeddedPiSessionDirect(
     const apiKeyInfo = await getApiKeyForModel({
       model,
       cfg: params.config,
-      profileId: params.authProfileId,
+      profileId: authProfileId,
       agentDir,
     });
 

src/agents/pi-embedded-runner/run/attempt.test.ts

@@ -639,6 +639,72 @@ describe("prependSystemPromptAddition", () => {
 });
 
 describe("buildAfterTurnLegacyCompactionParams", () => {
+  it("uses primary model when compaction.model is not set", () => {
+    const legacy = buildAfterTurnLegacyCompactionParams({
+      attempt: {
+        sessionKey: "agent:main:session:abc",
+        messageChannel: "slack",
+        messageProvider: "slack",
+        agentAccountId: "acct-1",
+        authProfileId: "openai:p1",
+        config: {} as OpenClawConfig,
+        skillsSnapshot: undefined,
+        senderIsOwner: true,
+        provider: "openai-codex",
+        modelId: "gpt-5.3-codex",
+        thinkLevel: "off",
+        reasoningLevel: "on",
+        extraSystemPrompt: "extra",
+        ownerNumbers: ["+15555550123"],
+      },
+      workspaceDir: "/tmp/workspace",
+      agentDir: "/tmp/agent",
+    });
+
+    expect(legacy).toMatchObject({
+      provider: "openai-codex",
+      model: "gpt-5.3-codex",
+    });
+  });
+
+  it("passes primary model through even when compaction.model is set (override resolved in compactDirect)", () => {
+    const legacy = buildAfterTurnLegacyCompactionParams({
+      attempt: {
+        sessionKey: "agent:main:session:abc",
+        messageChannel: "slack",
+        messageProvider: "slack",
+        agentAccountId: "acct-1",
+        authProfileId: "openai:p1",
+        config: {
+          agents: {
+            defaults: {
+              compaction: {
+                model: "openrouter/anthropic/claude-sonnet-4-5",
+              },
+            },
+          },
+        } as OpenClawConfig,
+        skillsSnapshot: undefined,
+        senderIsOwner: true,
+        provider: "openai-codex",
+        modelId: "gpt-5.3-codex",
+        thinkLevel: "off",
+        reasoningLevel: "on",
+        extraSystemPrompt: "extra",
+        ownerNumbers: ["+15555550123"],
+      },
+      workspaceDir: "/tmp/workspace",
+      agentDir: "/tmp/agent",
+    });
+
+    // buildAfterTurnLegacyCompactionParams no longer resolves the override;
+    // compactEmbeddedPiSessionDirect does it centrally for both auto + manual paths.
+    expect(legacy).toMatchObject({
+      provider: "openai-codex",
+      model: "gpt-5.3-codex",
+    });
+  });
+
   it("includes resolved auth profile fields for context-engine afterTurn compaction", () => {
     const legacy = buildAfterTurnLegacyCompactionParams({
       attempt: {