feat(backend): read Pi enabled model scope

backend/src/pi/enabled-models.ts

@@ -0,0 +1,78 @@
+import { readFileSync } from "node:fs";
+import { homedir } from "node:os";
+import { join } from "node:path";
+
+export interface PiEnabledModelsResult {
+  ids: string[];
+  warnings: string[];
+  source?: string;
+}
+
+interface LoadOptions {
+  harnessDir: string;
+  agentDir?: string;
+  read?: (path: string) => string;
+}
+
+type Settings = Record<string, unknown>;
+const INVALID = Symbol("invalid-settings");
+
+function readSettings(
+  path: string,
+  optional: boolean,
+  read: (path: string) => string,
+  warnings: string[],
+): Settings | undefined | typeof INVALID {
+  try {
+    const value = JSON.parse(read(path));
+    if (!value || typeof value !== "object" || Array.isArray(value)) throw new Error();
+    return value as Settings;
+  } catch (error) {
+    if (optional && (error as NodeJS.ErrnoException)?.code === "ENOENT") return undefined;
+    warnings.push(`Pi settings are unreadable or invalid: ${path}`);
+    return INVALID;
+  }
+}
+
+function isExactCompositeId(value: unknown): value is string {
+  if (typeof value !== "string" || /[\s*?:]/.test(value)) return false;
+  const parts = value.split("/");
+  return parts.length === 2 && parts.every((part) => part.length > 0);
+}
+
+export function loadPiEnabledModels(opts: LoadOptions): PiEnabledModelsResult {
+  const warnings: string[] = [];
+  const read = opts.read ?? ((path: string) => readFileSync(path, "utf8"));
+  const agentDir = opts.agentDir ?? join(homedir(), ".pi", "agent");
+  const globalPath = join(agentDir, "settings.json");
+  const projectPath = join(opts.harnessDir, ".pi", "settings.json");
+  const globalSettings = readSettings(globalPath, false, read, warnings);
+  const projectSettings = readSettings(projectPath, true, read, warnings);
+  if (globalSettings === INVALID || projectSettings === INVALID) return { ids: [], warnings };
+
+  const projectDefinesScope = projectSettings
+    ? Object.prototype.hasOwnProperty.call(projectSettings, "enabledModels")
+    : false;
+  const settings = projectDefinesScope ? projectSettings : globalSettings;
+  const source = projectDefinesScope ? projectPath : globalPath;
+  const raw = settings?.enabledModels;
+  if (!Array.isArray(raw) || raw.length === 0) {
+    warnings.push(`Pi enabledModels is missing or empty: ${source}`);
+    return { ids: [], warnings, source };
+  }
+
+  const ids: string[] = [];
+  const seen = new Set<string>();
+  raw.forEach((value, index) => {
+    if (!isExactCompositeId(value)) {
+      warnings.push(`Ignoring non-exact enabledModels entry at index ${index}: ${source}`);
+      return;
+    }
+    if (!seen.has(value)) {
+      seen.add(value);
+      ids.push(value);
+    }
+  });
+  if (ids.length === 0) warnings.push(`Pi enabledModels contains no exact model IDs: ${source}`);
+  return { ids, warnings, source };
+}

backend/test/enabled-models.test.ts

@@ -0,0 +1,98 @@
+import { expect, test } from "vitest";
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { loadPiEnabledModels } from "../src/pi/enabled-models.js";
+
+function fixture(globalValue: unknown, projectValue?: unknown) {
+  const root = mkdtempSync(join(tmpdir(), "tht-enabled-models-"));
+  const agentDir = join(root, "agent");
+  const harnessDir = join(root, "harness");
+  mkdirSync(agentDir, { recursive: true });
+  mkdirSync(join(harnessDir, ".pi"), { recursive: true });
+  writeFileSync(join(agentDir, "settings.json"), JSON.stringify(globalValue));
+  if (projectValue !== undefined) {
+    writeFileSync(join(harnessDir, ".pi", "settings.json"), JSON.stringify(projectValue));
+  }
+  return { root, agentDir, harnessDir };
+}
+
+test("loads exact global enabledModels in configured order", () => {
+  const f = fixture({ enabledModels: [
+    "zai/glm-5.2",
+    "deepseek/deepseek-v4-flash",
+    "local-qwen/qwen3.6-35b-a3b",
+  ] });
+  try {
+    expect(loadPiEnabledModels(f)).toMatchObject({
+      ids: [
+        "zai/glm-5.2",
+        "deepseek/deepseek-v4-flash",
+        "local-qwen/qwen3.6-35b-a3b",
+      ],
+      warnings: [],
+    });
+  } finally { rmSync(f.root, { recursive: true, force: true }); }
+});
+
+test("project enabledModels overrides global enabledModels", () => {
+  const f = fixture(
+    { enabledModels: ["zai/glm-5.2", "zai/glm-5v-turbo"] },
+    { enabledModels: ["local-qwen/qwen3.6-35b-a3b"] },
+  );
+  try {
+    expect(loadPiEnabledModels(f).ids).toEqual(["local-qwen/qwen3.6-35b-a3b"]);
+  } finally { rmSync(f.root, { recursive: true, force: true }); }
+});
+
+test("project settings without enabledModels fall back to global settings", () => {
+  const f = fixture({ enabledModels: ["zai/glm-5.2"] }, { theme: "thothii-mono" });
+  try {
+    expect(loadPiEnabledModels(f).ids).toEqual(["zai/glm-5.2"]);
+  } finally { rmSync(f.root, { recursive: true, force: true }); }
+});
+
+test("invalid entries are ignored, deduplicated, and reported without their content", () => {
+  const f = fixture({ enabledModels: [
+    "zai/glm-5.2", "zai/glm-5.2", "glm-5.2", "zai/*", "zai/glm-5.2:high", 7,
+  ] });
+  try {
+    const result = loadPiEnabledModels(f);
+    expect(result.ids).toEqual(["zai/glm-5.2"]);
+    expect(result.warnings).toHaveLength(4);
+    expect(result.warnings.join(" ")).not.toContain("glm-5.2:high");
+  } finally { rmSync(f.root, { recursive: true, force: true }); }
+});
+
+test.each([
+  ["missing field", {}],
+  ["empty field", { enabledModels: [] }],
+  ["wrong type", { enabledModels: "zai/glm-5.2" }],
+])("%s fails closed", (_name, settings) => {
+  const f = fixture(settings);
+  try {
+    const result = loadPiEnabledModels(f);
+    expect(result.ids).toEqual([]);
+    expect(result.warnings.length).toBeGreaterThan(0);
+  } finally { rmSync(f.root, { recursive: true, force: true }); }
+});
+
+test("malformed project settings fail closed instead of exposing global models", () => {
+  const f = fixture({ enabledModels: ["zai/glm-5.2"] });
+  writeFileSync(join(f.harnessDir, ".pi", "settings.json"), "{");
+  try {
+    const result = loadPiEnabledModels(f);
+    expect(result.ids).toEqual([]);
+    expect(result.warnings).toHaveLength(1);
+  } finally { rmSync(f.root, { recursive: true, force: true }); }
+});
+
+test("missing global settings fail closed", () => {
+  const f = fixture({ enabledModels: ["zai/glm-5.2"] });
+  rmSync(join(f.agentDir, "settings.json"));
+  try {
+    const result = loadPiEnabledModels(f);
+    expect(result.ids).toEqual([]);
+    expect(result.warnings).toHaveLength(1);
+  } finally { rmSync(f.root, { recursive: true, force: true }); }
+});