attach a PDF and the agent reads it; the microphone button is gone

Two requests, one file apart.

── The microphone ──

Removed from the chat composer. The HOOK stays: `useAudioRecording` and `blobToWav`
are also the file browser's DictateDialog, which is not what was asked to go.

── PDFs, by not extracting anything ──

A PDF entry sat in the attach menu once with no `onSelect` at all — the menu offered
it and did nothing, because nothing here could extract PDF text. It is back and real,
and it still extracts nothing: the file is uploaded, left on disk, and the agent is
given its PATH. Its own `Read` handles PDFs by page, better than any extraction this
could have shipped, and it can go back for a section later without paying for it
twice.

The alternative was base64 in the message. That is megabytes in the turn, re-sent for
the rest of the conversation, to produce worse text.

── What this uncovered ──

`attachmentIds` has been on this websocket and in `types.ts` for a long time and
NOTHING on the server read it. Images work because they travel separately as base64,
so the ids were dead on the wire — and a PDF is exactly the case that needs them. They
resolve to paths now, appended to the prompt as `Attached files (read from disk)`.

Ids arrive in a websocket message and become a filesystem path, so they are checked
rather than trusted: only the `<uuid>.<ext>` shape uploads actually generate, and only
in the two directories uploads actually write to. Verified — a valid id resolves, an
unknown one yields nothing, and `../../../../etc/passwd` and `; rm -rf /` yield
nothing.

Both upload directories are searched because the first message of a chat carries ids
written to `tmp/` (no session yet) and later ones carry ids under the session.

PDFs may be 25 MB against an image's 5: nothing carries them into a prompt, so the
ceiling is storage rather than context.

tsgo clean, frontend builds, 914 pass / 7 fail unchanged.

`[open]` For a MEMBER the file lands under `data/<email>/attachments/`, and whether
their Linux user can read it depends on the confinement ACLs. Untested — the owner
path is what was verified.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/servers/api/chat/websocket.ts

@@ -16,6 +16,7 @@ import { sendOpenCodeStreaming } from '@@/channels/send-opencode';
 import * as sidecar from '@@/sidecar-registry';
 import { join } from 'path';
 import { getOwnerHomeDir, getEmailAccountsDir } from '../../../servers/data-path';
+import { attachedFilePaths } from './attached-files';
 import { getUserSettings, getEmailAccounts, getChatEventsSince, appendChatEvent, getUserById } from 'officerdb';
 import { resolveHomeDir } from '@@/user-home';
 import { claudeLoginState } from '@@/os-user-claude';
@@ -360,10 +361,29 @@ async function handleChat(
   const sessionId = msg.sessionId || randomUUID();
 
   // Prepend resume summary to the prompt if present
-  const prompt = msg.resumeSummary
+  const withSummary = msg.resumeSummary
     ? `Here is a summary of a previous conversation to continue from:\n\n${msg.resumeSummary}\n\n---\n\nUser's new message: ${msg.prompt}`
     : msg.prompt;
 
+  /**
+   * Attached files, named by PATH rather than carried in the message.
+   *
+   * `attachmentIds` has been on this wire and in `types.ts` since before today and NOTHING read it —
+   * images work because they travel separately as base64, so the ids were dead. A PDF cannot travel that
+   * way: it would be megabytes of base64 in every turn of the conversation, re-sent forever.
+   *
+   * So the file stays on disk and the agent is told where it is. Reading a document is something its own
+   * tools already do better than a prompt can — page ranges, extraction, re-reading a section later
+   * without paying for it again — and this is a machine where the agent runs as the person who uploaded
+   * the file.
+   */
+  const attached = await attachedFilePaths(userId, sessionId, msg.attachmentIds);
+  const prompt = attached.length
+    ? `${withSummary}\n\nAttached ${attached.length === 1 ? 'file' : 'files'} (read from disk):\n${attached
+        .map((path) => `- ${path}`)
+        .join('\n')}`
+    : withSummary;
+
   // Use provided model, or fall back to user default, or the system default.
   const model = msg.model || (await getUserDefaultModel(userId)) || DEFAULT_MODEL;