Merge pull request #4138 from jeremymcs/claude/investigate-issue-4122-6Vi1I

fix(gsd): preserve custom-model selection on /gsd auto bootstrap (#4122)

src/resources/extensions/gsd/auto-start.ts

@@ -83,7 +83,11 @@ import { join } from "node:path";
 import { sep as pathSep } from "node:path";
 
 import { resolveProjectRootDbPath } from "./bootstrap/dynamic-tools.js";
-import { resolveDefaultSessionModel, resolveDynamicRoutingConfig } from "./preferences-models.js";
+import {
+  isCustomProvider,
+  resolveDefaultSessionModel,
+  resolveDynamicRoutingConfig,
+} from "./preferences-models.js";
 import type { WorktreeResolver } from "./worktree-resolver.js";
 import { getSessionModelOverride } from "./session-model-override.js";
 
@@ -274,8 +278,18 @@ export async function bootstrapAutoSession(
   //
   // This preserves #3517 defaults while honoring explicit runtime model
   // selection for subsequent /gsd runs in the same session.
+  //
+  // Exception (#4122): when the session provider is a custom provider declared
+  // in ~/.gsd/agent/models.json (Ollama, vLLM, OpenAI-compatible proxy, etc.),
+  // PREFERENCES.md is skipped entirely. PREFERENCES.md cannot reference custom
+  // providers, so honoring it would silently reroute auto-mode to a built-in
+  // provider the user is not logged into and surface as "Not logged in · Please
+  // run /login" before pausing and resetting to claude-code/claude-sonnet-4-6.
   const manualSessionOverride = getSessionModelOverride(ctx.sessionManager.getSessionId());
-  const preferredModel = resolveDefaultSessionModel(ctx.model?.provider);
+  const sessionProviderIsCustom = isCustomProvider(ctx.model?.provider);
+  const preferredModel = sessionProviderIsCustom
+    ? null
+    : resolveDefaultSessionModel(ctx.model?.provider);
   // Validate the preferred model against the live registry + provider auth so
   // an unconfigured PREFERENCES.md entry (no API key / OAuth) can't become the
   // start-model snapshot. Without this, every subsequent unit would try to

src/resources/extensions/gsd/preferences-models.ts

@@ -7,6 +7,8 @@
  */
 
 import { existsSync, readFileSync, writeFileSync } from "node:fs";
+import { homedir } from "node:os";
+import { join } from "node:path";
 import type { DynamicRoutingConfig } from "./model-router.js";
 import { defaultRoutingConfig } from "./model-router.js";
 import type { TokenProfile, InlineLevel } from "./types.js";
@@ -185,6 +187,45 @@ export function resolveDefaultSessionModel(
   return undefined;
 }
 
+/**
+ * Returns true if `provider` is defined as a custom provider in the user's
+ * `~/.gsd/agent/models.json` (Ollama, vLLM, LM Studio, OpenAI-compatible
+ * proxies, etc.).
+ *
+ * Used by auto-mode bootstrap to decide whether the session model
+ * (set via `/gsd model`) should override `PREFERENCES.md`.  Custom providers
+ * are never reachable from `PREFERENCES.md` (which only knows built-in
+ * providers), so when the user has explicitly selected one, it must take
+ * priority — otherwise auto-mode tries to start the built-in provider from
+ * PREFERENCES.md and fails with "Not logged in · Please run /login" (#4122).
+ *
+ * Reads models.json directly with a lightweight JSON parse to avoid
+ * pulling in the full model-registry at this call site.  Falls back to
+ * `~/.pi/agent/models.json` for parity with `resolveModelsJsonPath()`.
+ * Any read or parse error yields `false` (treat as not-custom) so a
+ * malformed models.json never breaks the session bootstrap.
+ */
+export function isCustomProvider(provider: string | undefined): boolean {
+  if (!provider) return false;
+  const candidates = [
+    join(homedir(), ".gsd", "agent", "models.json"),
+    join(homedir(), ".pi", "agent", "models.json"),
+  ];
+  for (const path of candidates) {
+    if (!existsSync(path)) continue;
+    try {
+      const raw = readFileSync(path, "utf-8");
+      const parsed = JSON.parse(raw) as { providers?: Record<string, unknown> };
+      if (parsed?.providers && Object.prototype.hasOwnProperty.call(parsed.providers, provider)) {
+        return true;
+      }
+    } catch {
+      // Ignore — malformed models.json must not break bootstrap.
+    }
+  }
+  return false;
+}
+
 /**
  * Determines the next fallback model to try when the current model fails.
  * If the current model is not in the configured list, returns the primary model.

src/resources/extensions/gsd/tests/auto-start-model-capture.test.ts

@@ -33,8 +33,12 @@ test("bootstrapAutoSession checks manual session override before preferences", (
   assert.ok(manualIdx > -1, "auto-start.ts should read session model override first");
 
   // resolveDefaultSessionModel() should still be called for fallback behavior
-  const preferredIdx = source.indexOf("const preferredModel = resolveDefaultSessionModel(");
-  assert.ok(preferredIdx > -1, "auto-start.ts should call resolveDefaultSessionModel()");
+  const preferredIdx = source.indexOf("const preferredModel = ");
+  assert.ok(preferredIdx > -1, "auto-start.ts should build preferredModel");
+  assert.ok(
+    source.indexOf("resolveDefaultSessionModel(") > -1,
+    "auto-start.ts should call resolveDefaultSessionModel()",
+  );
 
   // Session provider should be passed for bare model ID resolution
   const withProviderIdx = source.indexOf("resolveDefaultSessionModel(ctx.model?.provider)");
@@ -47,6 +51,51 @@ test("bootstrapAutoSession checks manual session override before preferences", (
     manualIdx < snapshotIdx && preferredIdx < snapshotIdx,
     "manual override and preference fallback must be resolved before building startModelSnapshot",
   );
+
+  // The validated preferred model must still appear as one of the snapshot
+  // sources so PREFERENCES.md continues to win over a stale settings.json
+  // default for built-in providers.
+  const snapshotBlock = source.slice(snapshotIdx, snapshotIdx + 400);
+  assert.ok(
+    snapshotBlock.includes("validatedPreferredModel") || snapshotBlock.includes("preferredModel"),
+    "startModelSnapshot must still consider preferredModel for built-in providers",
+  );
+});
+
+test("bootstrapAutoSession prefers session model over PREFERENCES.md when provider is custom (#4122)", () => {
+  // Custom providers (Ollama, vLLM, OpenAI-compatible proxies) live in
+  // ~/.gsd/agent/models.json, not PREFERENCES.md.  When the user picks one
+  // via /gsd model, that selection must win over any preferredModel from
+  // PREFERENCES.md, otherwise auto-mode tries to start a built-in provider
+  // the user is not logged into and pauses with "Not logged in".
+  const customCheckIdx = source.indexOf("isCustomProvider(ctx.model?.provider)");
+  assert.ok(
+    customCheckIdx > -1,
+    "auto-start.ts should call isCustomProvider() to detect custom-model sessions",
+  );
+
+  // sessionProviderIsCustom must gate preferredModel resolution so that when the
+  // session provider is custom, preferredModel is null and PREFERENCES.md is
+  // skipped entirely — the snapshot then falls through to ctx.model.
+  const gateIdx = source.indexOf("sessionProviderIsCustom");
+  assert.ok(gateIdx > -1, "auto-start.ts should bind sessionProviderIsCustom");
+
+  const preferredIdx = source.indexOf("const preferredModel = ");
+  assert.ok(preferredIdx > -1, "auto-start.ts should build preferredModel");
+
+  const preferredBlock = source.slice(preferredIdx, preferredIdx + 200);
+  assert.ok(
+    preferredBlock.includes("sessionProviderIsCustom"),
+    "preferredModel must be gated on sessionProviderIsCustom so PREFERENCES.md is skipped for custom providers",
+  );
+
+  const snapshotIdx = source.indexOf("const startModelSnapshot = ");
+  assert.ok(snapshotIdx > -1, "auto-start.ts should build startModelSnapshot");
+
+  assert.ok(
+    customCheckIdx < preferredIdx && preferredIdx < snapshotIdx,
+    "isCustomProvider() must be evaluated before preferredModel, which must be resolved before startModelSnapshot",
+  );
 });
 
 test("bootstrapAutoSession validates preferred model against live registry auth (#unconfigured-models)", () => {

src/resources/extensions/gsd/tests/model-isolation.test.ts

@@ -1,6 +1,8 @@
 /**
- * Tests for model config isolation between concurrent instances (#650, #1065)
- * and session-scoped model precedence behavior.
+ * Tests for model config isolation between concurrent instances (#650, #1065),
+ * session-scoped model precedence behavior including manual session override,
+ * GSD preferences override of settings.json defaults (#3517), and custom
+ * provider precedence over PREFERENCES.md when set via `/gsd model` (#4122).
  */
 
 import { describe, it, beforeEach, afterEach } from "node:test";
@@ -214,3 +216,90 @@ describe("manual session model override precedence", () => {
       "should be null when no model source is available");
   });
 });
+
+// ─── Custom provider session model wins over PREFERENCES.md (#4122) ─────────
+
+describe("custom provider session model overrides PREFERENCES.md (#4122)", () => {
+  // Mirrors the auto-start.ts logic:
+  //   sessionProviderIsCustom && ctx.model
+  //     ? ctx.model
+  //     : (preferredModel ?? ctx.model ?? null)
+  function selectStartModel(args: {
+    ctxModel: { provider: string; id: string } | null;
+    preferredModel: { provider: string; id: string } | undefined;
+    sessionProviderIsCustom: boolean;
+  }): { provider: string; id: string } | null {
+    const { ctxModel, preferredModel, sessionProviderIsCustom } = args;
+    if (sessionProviderIsCustom && ctxModel) {
+      return { provider: ctxModel.provider, id: ctxModel.id };
+    }
+    return preferredModel
+      ?? (ctxModel ? { provider: ctxModel.provider, id: ctxModel.id } : null);
+  }
+
+  it("custom provider from /gsd model wins over PREFERENCES.md built-in default", () => {
+    // User runs `/gsd model ollama/llama3.1:8b`, then `/gsd auto`.
+    // PREFERENCES.md still has the project-template claude-code default.
+    const ctxModel = { provider: "ollama", id: "llama3.1:8b" };
+    const preferredModel = { provider: "claude-code", id: "claude-sonnet-4-6" };
+
+    const snapshot = selectStartModel({
+      ctxModel,
+      preferredModel,
+      sessionProviderIsCustom: true,
+    });
+
+    assert.equal(snapshot?.provider, "ollama",
+      "custom-provider session model must win over PREFERENCES.md");
+    assert.equal(snapshot?.id, "llama3.1:8b",
+      "custom-provider session model id must be preserved");
+    assert.notEqual(snapshot?.provider, "claude-code",
+      "claude-code from PREFERENCES.md must NOT be selected when session is custom");
+  });
+
+  it("built-in session provider still defers to PREFERENCES.md (#3517 preserved)", () => {
+    // ctx.model is a built-in provider (claude-code) but PREFERENCES.md has
+    // an explicit openai-codex preference.  PREFERENCES.md should still win.
+    const ctxModel = { provider: "claude-code", id: "claude-sonnet-4-6" };
+    const preferredModel = { provider: "openai-codex", id: "gpt-5.4" };
+
+    const snapshot = selectStartModel({
+      ctxModel,
+      preferredModel,
+      sessionProviderIsCustom: false,
+    });
+
+    assert.equal(snapshot?.provider, "openai-codex",
+      "PREFERENCES.md must still win when session provider is built-in");
+    assert.equal(snapshot?.id, "gpt-5.4");
+  });
+
+  it("custom provider with no PREFERENCES.md still uses ctx.model", () => {
+    const ctxModel = { provider: "vllm", id: "qwen2.5-coder:32b" };
+
+    const snapshot = selectStartModel({
+      ctxModel,
+      preferredModel: undefined,
+      sessionProviderIsCustom: true,
+    });
+
+    assert.equal(snapshot?.provider, "vllm");
+    assert.equal(snapshot?.id, "qwen2.5-coder:32b");
+  });
+
+  it("null ctx.model with custom flag falls through to preferredModel", () => {
+    // Defensive: sessionProviderIsCustom can only be true if ctx.model exists,
+    // but verify the guard works if that invariant is ever broken.
+    const preferredModel = { provider: "claude-code", id: "claude-sonnet-4-6" };
+
+    const snapshot = selectStartModel({
+      ctxModel: null,
+      preferredModel,
+      sessionProviderIsCustom: true,
+    });
+
+    assert.equal(snapshot?.provider, "claude-code",
+      "should fall back to preferredModel when ctx.model is null");
+  });
+});
+