fix(backend): inject provider credentials from file

backend/src/config.ts

@@ -1,3 +1,5 @@
+import path from "node:path";
+
 export interface AppConfig {
   host: string; port: number; harnessDir: string; thtBin: string; piBin: string;
   authMode: "none" | "mock" | "upstream";
@@ -6,6 +8,7 @@ export interface AppConfig {
   settingsFile: string;
   dataRoot?: string;
   ollamaEnsureTimeoutMs: number;
+  modelApiKeyFile?: string;
 }
 export function loadConfig(env: Record<string, string | undefined>): AppConfig {
   const authMode = env.AUTH_MODE ?? "none";
@@ -15,6 +18,15 @@ export function loadConfig(env: Record<string, string | undefined>): AppConfig {
   if (env.THOTH_PUBLIC_EXPOSURE === "true" && authMode !== "upstream") {
     throw new Error("public exposure requires AUTH_MODE=upstream behind a trusted proxy");
   }
+  const modelApiKeyFile = env.THT_MODEL_API_KEY_FILE;
+  if (modelApiKeyFile !== undefined && (
+    modelApiKeyFile.trim() !== modelApiKeyFile
+    || modelApiKeyFile.length === 0
+    || modelApiKeyFile.includes("\0")
+    || !path.isAbsolute(modelApiKeyFile)
+  )) {
+    throw new Error("model credential configuration is invalid");
+  }
   return {
     host: env.HOST ?? "127.0.0.1",
     port: Number(env.PORT ?? 8787),
@@ -27,5 +39,6 @@ export function loadConfig(env: Record<string, string | undefined>): AppConfig {
     settingsFile: env.SETTINGS_FILE ?? "data/settings.json",
     dataRoot: env.THT_DATA_ROOT,
     ollamaEnsureTimeoutMs: Number(env.OLLAMA_ENSURE_TIMEOUT_MS ?? 60000),
+    modelApiKeyFile,
   };
 }

backend/src/pi/pi-process-manager.ts

@@ -1,4 +1,5 @@
 import { spawn as nodeSpawn, type ChildProcessWithoutNullStreams } from "node:child_process";
+import { closeSync, constants, fstatSync, lstatSync, openSync, readFileSync } from "node:fs";
 import type { AppConfig } from "../config.js";
 import { RpcClient } from "../rpc/rpc-client.js";
 import { SessionBridge } from "../bridge/session-bridge.js";
@@ -17,26 +18,90 @@ type SpawnFn = (
   options: { cwd: string; env: NodeJS.ProcessEnv },
 ) => ChildProcessWithoutNullStreams;
 
+const PROVIDER_KEY_ENV: Readonly<Record<string, string>> = {
+  anthropic: "ANTHROPIC_API_KEY",
+  openai: "OPENAI_API_KEY",
+  gemini: "GEMINI_API_KEY",
+  google: "GEMINI_API_KEY",
+  deepseek: "DEEPSEEK_API_KEY",
+  zai: "ZAI_API_KEY",
+  groq: "GROQ_API_KEY",
+  mistral: "MISTRAL_API_KEY",
+  openrouter: "OPENROUTER_API_KEY",
+  xai: "XAI_API_KEY",
+  cerebras: "CEREBRAS_API_KEY",
+  cohere: "COHERE_API_KEY",
+};
+const LOCAL_PROVIDERS = new Set(["ollama", "lmstudio", "local", "aritmolab"]);
+const PROVIDER_ENV_NAMES = new Set(Object.values(PROVIDER_KEY_ENV));
+
+function normalizedProvider(provider: string | undefined): string | undefined {
+  const value = provider?.trim().toLowerCase();
+  return value || undefined;
+}
+
+function readModelCredential(file: string): string {
+  let fd: number | undefined;
+  try {
+    const before = lstatSync(file);
+    if (!before.isFile() || before.isSymbolicLink() || before.nlink !== 1) throw new Error();
+    fd = openSync(file, constants.O_RDONLY | constants.O_NOFOLLOW);
+    const info = fstatSync(fd);
+    const mode = info.mode & 0o777;
+    const ownedStrict = info.uid === process.getuid?.() && (mode === 0o400 || mode === 0o600);
+    const dockerSecret = file.startsWith("/run/secrets/") && mode === 0o444;
+    if (!info.isFile() || info.nlink !== 1 || (!ownedStrict && !dockerSecret) || info.size > 16_384) {
+      throw new Error();
+    }
+    const value = readFileSync(fd, "utf8");
+    if (!value || /\s/.test(value)) throw new Error();
+    return value;
+  } catch {
+    throw new Error("model provider credential is unavailable");
+  } finally {
+    if (fd !== undefined) closeSync(fd);
+  }
+}
+
 export class PiProcessManager {
   private runtimes = new Map<string, SessionRuntime>();
-  private spawnFn: (sessionId: string, author: string) => ChildProcessWithoutNullStreams;
+  private spawnFn: (
+    sessionId: string, author: string, provider: string | undefined,
+  ) => ChildProcessWithoutNullStreams;
 
   constructor(private cfg: AppConfig, opts?: { spawnFn?: SpawnFn }) {
     if (opts?.spawnFn) {
-      this.spawnFn = (sessionId: string, author: string) => this.spawnPi(opts.spawnFn!, sessionId, author);
+      this.spawnFn = (sessionId, author, provider) =>
+        this.spawnPi(opts.spawnFn!, sessionId, author, provider);
     } else {
-      this.spawnFn = (sessionId: string, author: string) => this.spawnPi(nodeSpawn, sessionId, author);
+      this.spawnFn = (sessionId, author, provider) =>
+        this.spawnPi(nodeSpawn, sessionId, author, provider);
     }
   }
 
-  private spawnPi(spawnFn: SpawnFn, sessionId: string, author: string): ChildProcessWithoutNullStreams {
+  private spawnPi(
+    spawnFn: SpawnFn, sessionId: string, author: string, provider: string | undefined,
+  ): ChildProcessWithoutNullStreams {
     const env: NodeJS.ProcessEnv = {
       ...process.env,
       THT_SESSION: sessionId,
       THT_AUTHOR: author,
     };
     delete env.THT_DATA_ROOT;
+    delete env.PI_PROVIDER_API_KEY;
+    delete env.THT_MODEL_API_KEY_FILE;
+    for (const name of PROVIDER_ENV_NAMES) delete env[name];
     if (this.cfg.dataRoot !== undefined) env.THT_DATA_ROOT = this.cfg.dataRoot;
+    const normalized = normalizedProvider(provider);
+    if (normalized && !LOCAL_PROVIDERS.has(normalized)) {
+      const envName = PROVIDER_KEY_ENV[normalized];
+      if (!envName || !this.cfg.modelApiKeyFile) {
+        throw new Error("model provider credential is unavailable");
+      }
+      env[envName] = readModelCredential(this.cfg.modelApiKeyFile);
+    } else if (this.cfg.modelApiKeyFile && !normalized) {
+      throw new Error("model provider credential is unavailable");
+    }
     // pi 0.73 removed `--approve`: rpc mode is headless and its argv is intentionally minimal.
     const child = spawnFn(this.cfg.piBin, ["--mode", "rpc"], {
       cwd: this.cfg.harnessDir,
@@ -67,7 +132,8 @@ export class PiProcessManager {
       throw new Error("max Pi processes reached");
     }
     const author = o.author ?? "dev@local";
-    const child = this.spawnFn(sessionId, author);
+    const provider = o.provider ?? this.cfg.defaults.provider;
+    const child = this.spawnFn(sessionId, author, provider);
     const rpc = new RpcClient(child);
     const bridge = new SessionBridge(rpc);
     const rt: SessionRuntime = { rpc, bridge, child };
@@ -88,7 +154,6 @@ export class PiProcessManager {
       }
     });
 
-    const provider = o.provider ?? this.cfg.defaults.provider;
     const model = o.model ?? this.cfg.defaults.model;
     const thinking = o.thinking ?? this.cfg.defaults.thinking;