fix(discord): check-then-read gaps name the file by label, never the path (#1873)

A token file, context file, tool root, data root or setspark key file
that changes between its check and its read failed with a native error
whose message carried the host path. Each read now names the file by
label and code (quietRead): same error object, type and code, so exit
codes, refusal codes and check order are unchanged.

packages/discord/src/binding.mjs

@@ -313,7 +313,13 @@ export function loadBinding(path) {
 // clients. It is never printed, journaled, or put on a command line.
 export function readToken(binding) {
   checkPrivateFile(binding.tokenFile, "token file");
-  const token = readFileSync(binding.tokenFile, "utf8").trim();
+  // A file that changes after its check fails with a native error that carries the path (#1873).
+  let token;
+  try {
+    token = readFileSync(binding.tokenFile, "utf8").trim();
+  } catch (e) {
+    throw quietRead(e, "token file");
+  }
   if (!/^[A-Za-z0-9._-]{20,}$/.test(token)) throw new DiscordError("token file does not hold a bot token");
   return token;
 }
@@ -345,7 +351,12 @@ export function resolveContextFiles(binding, repo) {
     }
     if (st.isSymbolicLink()) throw new DiscordError(`context file must not be a symlink: ${at}`);
     if (!st.isFile() || st.size === 0) throw new DiscordError(`context file is not a regular non-empty file: ${at}`);
-    const real = realpathSync(path);
+    let real;
+    try {
+      real = realpathSync(path);
+    } catch (e) {
+      throw quietRead(e, `context file ${at}`);
+    }
     if (real !== path || !real.startsWith(root + sep)) throw new DiscordError(`context file resolves outside the repository: ${at}`);
     return path;
   });
@@ -379,7 +390,12 @@ function webConfig(raw, where) {
 
 export function resolveToolRoots(binding, { dataRoot }) {
   if (!binding.tools) return null;
-  const data = existsSync(dataRoot) ? realpathSync(dataRoot) : resolve(dataRoot);
+  let data;
+  try {
+    data = existsSync(dataRoot) ? realpathSync(dataRoot) : resolve(dataRoot);
+  } catch (e) {
+    throw quietRead(e, "the data root");
+  }
   const roots = binding.tools.roots.map((r) => {
     let st;
     try {
@@ -389,7 +405,12 @@ export function resolveToolRoots(binding, { dataRoot }) {
     }
     if (st.isSymbolicLink()) throw new DiscordError(`tool root ${r.name} must not be a symlink`);
     if (!st.isDirectory()) throw new DiscordError(`tool root ${r.name} is not a directory`);
-    const real = realpathSync(r.path);
+    let real;
+    try {
+      real = realpathSync(r.path);
+    } catch (e) {
+      throw quietRead(e, `tool root ${r.name}`);
+    }
     if (real === data || real.startsWith(data + sep) || data.startsWith(real + sep)) throw new DiscordError(`tool root ${r.name} overlaps the data root`);
     return { name: r.name, path: real, write: r.write, ...(r.git ? { git: { branch: r.git.branch, identity: r.git.identity, tokenFile: r.git.tokenFile, author: `${r.git.author.name} <${r.git.author.email}>`, ...(r.git.protocol ? { protocol: r.git.protocol } : {}) } } : {}) };
   });

packages/discord/src/setspark.mjs

@@ -28,7 +28,7 @@
 import { lstatSync, readFileSync } from "node:fs";
 import { request as httpsRequest } from "node:https";
 import { request as httpRequest } from "node:http";
-import { plainKey } from "./errors.mjs";
+import { plainKey, quietRead } from "./errors.mjs";
 
 export const SETSPARK_DEFAULTS = Object.freeze({ timeoutMs: 15000, maxResponseBytes: 262144 });
 export const USER_AGENT = "mosaic-discord-sage/1 (Mosaic Stack Discord connector; setspark client)";
@@ -133,7 +133,14 @@ export function readKey(config) {
     throw new SetsparkRefusal(SETSPARK_REFUSAL.KEY_FILE);
   }
   if (st.size > KEY_MAX_BYTES) throw new SetsparkRefusal(SETSPARK_REFUSAL.KEY_SHAPE);
-  const text = readFileSync(config.keyFile, "utf8");
+  // A file that changes after its checks fails with a native error that carries the path: it
+  // keeps its type and code and names the field (#1873).
+  let text;
+  try {
+    text = readFileSync(config.keyFile, "utf8");
+  } catch (e) {
+    throw quietRead(e, "keyFile");
+  }
   // Either one bare key line, or the mint's own JSON output
   // ({"key_id", "key", "note"}) stored as is; only "key" is used.
   let key = text;

packages/discord/tests/path-redaction-labels.test.mjs

@@ -3,7 +3,8 @@
 // quotes the sentinel too; each test also checks the scratch root and the label.
 import { test } from 'node:test';
 import assert from 'node:assert/strict';
-import { mkdtempSync, mkdirSync, writeFileSync, rmSync } from 'node:fs';
+import fs, { mkdtempSync, mkdirSync, writeFileSync, rmSync } from 'node:fs';
+import { syncBuiltinESMExports } from 'node:module';
 import { readApprovals } from '../src/approvals.mjs';
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
@@ -11,7 +12,7 @@ import { DiscordError } from '../src/errors.mjs';
 import { bindingDataDir, bindingPath, loadDataRoot, readToken, resolveContextFiles, resolveToolRoots, validateBinding } from '../src/binding.mjs';
 import { ensureJournal, lockPath, ownerPath, readInboxIds, recover, requestStop, turnPath, unlock, writeTurn } from '../src/journal.mjs';
 import { gitPull, loadGitConfig } from '../src/git.mjs';
-import { loadSetsparkConfig } from '../src/setspark.mjs';
+import { loadSetsparkConfig, readKey } from '../src/setspark.mjs';
 
 const secret = 'sk-test-NOT-A-SECRET-1234';
 function scratch(t) {
@@ -134,3 +135,70 @@ test('a git refusal drops stderr lines that carry a host path and a spawn failur
   const failed = () => ({ error: Object.assign(new Error(`spawn ${join(dir, 'git')} ENOENT`), { code: 'ENOENT' }) });
   assert.throws(() => gitPull(rootCfg, { spawn: failed }), e => labelled('git could not start (ENOENT)', root, Error)(e));
 });
+
+// Re-check (#1873): a file removed between its check and its read surfaces a native
+// error. Each site names the file by label and code; the error's path never reaches the
+// message. `race` swaps one node:fs function so the target goes away right before the
+// real call, which then fails with a genuine ENOENT that names the path.
+function race(t, fn, target, remove) {
+  const original = fs[fn];
+  const swapped = function (p, ...rest) {
+    if (String(p) === target) remove();
+    return original.call(this, p, ...rest);
+  };
+  if (original.native) swapped.native = original.native;
+  fs[fn] = swapped;
+  syncBuiltinESMExports();
+  t.after(() => {
+    fs[fn] = original;
+    syncBuiltinESMExports();
+  });
+}
+
+test('a token file removed between its check and its read names the token file', t => {
+  const { root, dir } = scratch(t);
+  const tokenFile = join(dir, 'token');
+  writeFileSync(tokenFile, 'x'.repeat(30), { mode: 0o600 });
+  race(t, 'readFileSync', tokenFile, () => rmSync(tokenFile));
+  assert.throws(() => readToken({ tokenFile }), labelled('cannot read token file (ENOENT)', root, Error));
+});
+
+test('a context file removed between its check and its realpath names its index', t => {
+  const { root, dir } = scratch(t);
+  const repo = join(dir, 'repo');
+  mkdirSync(repo);
+  writeFileSync(join(repo, 'ok.md'), 'ok');
+  writeFileSync(join(repo, `${secret}.md`), 'x');
+  const target = join(repo, `${secret}.md`);
+  race(t, 'realpathSync', target, () => rmSync(target));
+  assert.throws(() => resolveContextFiles({ context: { files: ['ok.md', `${secret}.md`] } }, repo), labelled('cannot read context file context.files[1] (ENOENT)', root, Error));
+});
+
+test('a tool root removed between its check and its realpath names the root', t => {
+  const { root, dir } = scratch(t);
+  const docs = join(dir, 'docs');
+  mkdirSync(docs);
+  const binding = { tools: { roots: [{ name: 'docs', path: docs, write: false }] } };
+  race(t, 'realpathSync', docs, () => rmSync(docs, { recursive: true }));
+  assert.throws(() => resolveToolRoots(binding, { dataRoot: join(dir, 'data') }), labelled('cannot read tool root docs (ENOENT)', root, Error));
+});
+
+test('a data root removed between its check and its realpath names the data root', t => {
+  const { root, dir } = scratch(t);
+  const docs = join(dir, 'docs');
+  mkdirSync(docs);
+  const binding = { tools: { roots: [{ name: 'docs', path: docs, write: false }] } };
+  const data = join(dir, 'data');
+  mkdirSync(data);
+  race(t, 'realpathSync', data, () => rmSync(data, { recursive: true }));
+  assert.throws(() => resolveToolRoots(binding, { dataRoot: data }), labelled('cannot read the data root (ENOENT)', root, Error));
+});
+
+test('a setspark key file removed between its check and its read names keyFile', t => {
+  const { root, dir } = scratch(t);
+  const keyFile = join(dir, 'key');
+  writeFileSync(keyFile, 'ssk_' + 'a'.repeat(40), { mode: 0o600 });
+  const config = loadSetsparkConfig({ baseUrl: 'https://setspark.example', keyFile, principal: 'sage' });
+  race(t, 'readFileSync', keyFile, () => rmSync(keyFile));
+  assert.throws(() => readKey(config), labelled('cannot read keyFile (ENOENT)', root, Error));
+});