experiment(confidence-engine): route UI journey provider centrally

tests/app/api/cases-overview-route.test.js

@@ -0,0 +1,29 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const mockSynthesize = vi.fn();
+
+vi.mock("@/lib/graph/investigation-overview-synthesis.js", () => ({
+  synthesizeInvestigationOverview: (...args) => mockSynthesize(...args),
+}));
+
+vi.mock("@/lib/llm/provider.js", () => ({
+  getProvider: () => ({ generateReconstruction() {} }),
+  getProviderModelName: () => "gpt-5.6-terra",
+}));
+
+describe("POST /api/cases/overview provider routing", () => {
+  beforeEach(() => mockSynthesize.mockClear());
+
+  it("passes the central provider and model resolution to overview synthesis", async () => {
+    mockSynthesize.mockResolvedValue({ understanding: "Understanding", plausibleInterpretations: "None" });
+    const { POST } = await import("@/app/api/cases/overview/route.js");
+    const response = await POST(new Request("http://localhost/api/cases/overview", {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({ situationGraph: { nodes: [], edges: [] }, findings: [], plausibleInterpretations: [] }),
+    }));
+
+    expect(response.status).toBe(200);
+    expect(mockSynthesize.mock.calls[0][1]).toMatchObject({ modelName: "gpt-5.6-terra" });
+  });
+});

tests/app/api/cases-start-route.test.js

@@ -39,6 +39,8 @@ describe("app/api/cases/start route", () => {
     await POST(request);
 
     expect(mockStartCase).toHaveBeenCalledWith({ scenario: "Scenario text" });
+    expect(mockStartCase.mock.calls[0][0]).not.toHaveProperty("provider");
+    expect(mockStartCase.mock.calls[0][0]).not.toHaveProperty("modelName");
   });
 
   it("returns 200 on success", async () => {

tests/app/api/cases-update-route.test.js

@@ -72,6 +72,8 @@ describe("app/api/cases/update route", () => {
     );
 
     expect(mockUpdateCase).toHaveBeenCalledWith(body, { applyProposal: true });
+    expect(mockUpdateCase.mock.calls[0][0]).not.toHaveProperty("provider");
+    expect(mockUpdateCase.mock.calls[0][0]).not.toHaveProperty("modelName");
   });
 
   it("invalid JSON returns 400", async () => {

tests/app/api/current-understanding-synthesis-route.test.js

@@ -10,6 +10,7 @@ vi.mock("@/lib/graph/current-understanding-synthesis.js", () => ({
 
 vi.mock("@/lib/llm/provider.js", () => ({
   getProvider: () => ({}),
+  getProviderModelName: () => "gpt-5.6-terra",
 }));
 
 // ── Helpers ─────────────────────────────────────────────────
@@ -45,6 +46,7 @@ describe("POST /api/cases/synthesis — valid request", () => {
     expect(data.success).toBe(true);
     expect(data.currentUnderstanding).toBe("Synthesized result");
     expect(mockSynthesize).toHaveBeenCalledTimes(1);
+    expect(mockSynthesize.mock.calls[0][1]).toMatchObject({ modelName: "gpt-5.6-terra" });
   });
 
   it("returns narrative result on success", async () => {

tests/focused-deconstruct-boundary.test.js

@@ -51,6 +51,7 @@ describe("focused-deconstruct targetNodeId identity boundary", () => {
 
     vi.doMock("@/lib/llm/provider", () => ({
       getProvider: () => makeMockProvider(inventedModelId),
+      getProviderModelName: () => "configured-model",
     }));
 
     const { POST } = await import("../app/api/focused-investigation/deconstruct/route.js");
@@ -97,6 +98,7 @@ describe("focused-deconstruct targetNodeId identity boundary", () => {
     });
     vi.doMock("@/lib/llm/provider", () => ({
       getProvider: () => ({ generateReconstruction }),
+      getProviderModelName: () => "gpt-5.6-terra",
     }));
     const { POST } = await import("../app/api/focused-investigation/deconstruct/route.js");
 
@@ -116,7 +118,7 @@ describe("focused-deconstruct targetNodeId identity boundary", () => {
     expect(response.status).toBe(200);
     expect(generateReconstruction).toHaveBeenCalledWith(
       expect.any(String),
-      process.env.OLLAMA_MODEL,
+      "gpt-5.6-terra",
       focusedDeconstructJsonSchema,
     );
   });
@@ -149,6 +151,7 @@ describe("focused-deconstruct targetNodeId identity boundary", () => {
           providerExecution: { chatRequestAttempted: true },
         }),
       }),
+      getProviderModelName: () => "configured-model",
     }));
 
     const { POST } = await import("../app/api/focused-investigation/deconstruct/route.js");
@@ -228,6 +231,7 @@ describe("focused-deconstruct targetNodeId identity boundary", () => {
           providerExecution: { chatRequestAttempted: true },
         }),
       }),
+      getProviderModelName: () => "configured-model",
     }));
 
     const { POST } = await import("../app/api/focused-investigation/deconstruct/route.js");
@@ -291,6 +295,7 @@ describe("focused-deconstruct targetNodeId identity boundary", () => {
           providerExecution: { chatRequestAttempted: true, chatRequestSucceeded: true },
         }),
       }),
+      getProviderModelName: () => "configured-model",
     }));
 
     const { POST } = await import("../app/api/focused-investigation/deconstruct/route.js");

tests/graph/episode-reasoning-seam.test.js

@@ -1,5 +1,10 @@
 import { beforeEach, describe, expect, it, vi } from "vitest";
 
+vi.mock("@/lib/llm/provider.js", () => ({
+  getProvider: () => ({ generateReconstruction() {} }),
+  getProviderModelName: () => "gpt-5.6-terra",
+}));
+
 // ── Fixtures ────────────────────────────────────────────────
 
 function makePreparedEpisode(overrides = {}) {
@@ -193,4 +198,22 @@ describe("episode reasoning seam (reconsiderCompletedEpisode)", () => {
     else process.env.OLLAMA_MODEL = prevModel;
   });
 
+  it("uses the central provider model resolution when episode mode supplies no model override", async () => {
+    const provider = {
+      generateReconstruction: vi.fn().mockResolvedValue(makeProposalResponse()),
+    };
+    const { reconsiderCompletedEpisode } = await import("@/lib/graph/orchestrator.js");
+
+    const result = await reconsiderCompletedEpisode(
+      { ...TEST_EPISODE, provider },
+      { buildEpisodePrompt: () => "EPISODE_PROMPT" },
+    );
+
+    expect(result.success).toBe(true);
+    expect(provider.generateReconstruction).toHaveBeenCalledWith(
+      "EPISODE_PROMPT",
+      "gpt-5.6-terra",
+    );
+  });
+
 });

tests/llm/provider.test.js

@@ -4,6 +4,7 @@ import {
   createOpenAIStrictSchema,
   createOpenAIReconstructionProvider,
   getProvider,
+  getProviderModelName,
   normaliseOpenAITransportResponse,
   reconstructionJsonSchema,
 } from "@/lib/llm/provider.js";
@@ -11,6 +12,48 @@ import { reconstructionV2Schema } from "@/lib/reconstruction/schema.js";
 import { z } from "zod";
 
 describe("OllamaLlmProvider chat capability detection", () => {
+  it("keeps Ollama and its configured model when no experiment provider is selected", () => {
+    const previousExperimentProvider = process.env.CONFIDENCE_ENGINE_EXPERIMENT_PROVIDER;
+    const previousModel = process.env.OLLAMA_MODEL;
+    const previousOpenAIKey = process.env.OPENAI_API_KEY;
+    delete process.env.CONFIDENCE_ENGINE_EXPERIMENT_PROVIDER;
+    process.env.OLLAMA_MODEL = "qwen-default";
+    process.env.OPENAI_API_KEY = "present-but-not-selected";
+
+    try {
+      expect(getProvider().constructor.name).toBe("OllamaLlmProvider");
+      expect(getProviderModelName()).toBe("qwen-default");
+    } finally {
+      if (previousExperimentProvider === undefined) delete process.env.CONFIDENCE_ENGINE_EXPERIMENT_PROVIDER;
+      else process.env.CONFIDENCE_ENGINE_EXPERIMENT_PROVIDER = previousExperimentProvider;
+      if (previousModel === undefined) delete process.env.OLLAMA_MODEL;
+      else process.env.OLLAMA_MODEL = previousModel;
+      if (previousOpenAIKey === undefined) delete process.env.OPENAI_API_KEY;
+      else process.env.OPENAI_API_KEY = previousOpenAIKey;
+    }
+  });
+
+  it("selects the existing OpenAI provider and Terra only for the explicit experiment configuration", () => {
+    const previousExperimentProvider = process.env.CONFIDENCE_ENGINE_EXPERIMENT_PROVIDER;
+    const previousModel = process.env.OLLAMA_MODEL;
+    const previousOpenAIKey = process.env.OPENAI_API_KEY;
+    process.env.CONFIDENCE_ENGINE_EXPERIMENT_PROVIDER = "openai";
+    process.env.OPENAI_API_KEY = "test-key";
+    process.env.OLLAMA_MODEL = "qwen-default";
+
+    try {
+      expect(getProvider().constructor.name).toBe("OpenAIReconstructionProvider");
+      expect(getProviderModelName()).toBe("gpt-5.6-terra");
+    } finally {
+      if (previousExperimentProvider === undefined) delete process.env.CONFIDENCE_ENGINE_EXPERIMENT_PROVIDER;
+      else process.env.CONFIDENCE_ENGINE_EXPERIMENT_PROVIDER = previousExperimentProvider;
+      if (previousModel === undefined) delete process.env.OLLAMA_MODEL;
+      else process.env.OLLAMA_MODEL = previousModel;
+      if (previousOpenAIKey === undefined) delete process.env.OPENAI_API_KEY;
+      else process.env.OPENAI_API_KEY = previousOpenAIKey;
+    }
+  });
+
   it("uses the configured model for the chat probe and keeps the chat path", async () => {
     const originalBaseUrl = process.env.OLLAMA_BASE_URL;
     const fetchSpy = vi.fn()