List a conversation's whole file tree, not just its top level

grab-conversation-files asked listBotFiles for the top level only, and a
bot saves into folders (reports/, seo/coderank/, tmp/...). The page
therefore carried none of the files a reply named, so every [file:ID]
chip rendered as dead plain text and the files could not be opened at
all: the bot had done the work and the user had no way to reach it.

The props now take the whole tree, and a chip that still isn't among
them (a message older than the page's first page of files) fetches its
one file by id, cached per id so a deleted one doesn't refetch on every
render.

src/functions/backend/db/bot-files/conversation-files-sql.test.ts

@@ -0,0 +1,50 @@
+import { describe, expect, test } from "bun:test";
+import { Database } from "bun:sqlite";
+
+/**
+ * The shape `listBotFiles` uses for a conversation's props. It has to be the
+ * whole folder tree: a bot saves into paths like `reports/` and
+ * `seo/coderank/`, and a `[file:ID]` chip in a message can only resolve
+ * against the files in these props, so a top-level-only list left every
+ * nested file ref as unclickable plain text in the chat.
+ */
+function rows({ db, scopes, recursive }: { db: Database; scopes: { scope: string; owner_id: number }[]; recursive: boolean }) {
+    const owner_sql = scopes.map(() => `(scope = ? AND owner_id = ?)`).join(" OR ");
+    const values = scopes.flatMap((s) => [s.scope, s.owner_id]);
+    const where = [owner_sql];
+
+    if (!recursive) where.push(`(folder = '' OR folder IS NULL)`);
+
+    return db
+        .query(`SELECT id FROM bot_files WHERE ${where.join(" AND ")} ORDER BY id`)
+        .all(...values)
+        .map((row) => (row as { id: number }).id);
+}
+
+const db = new Database(":memory:");
+
+db.run(`CREATE TABLE bot_files (id INTEGER PRIMARY KEY, scope TEXT, owner_id INTEGER, folder TEXT, path TEXT)`);
+db.run(
+    `INSERT INTO bot_files VALUES
+        (1, 'bot', 6, '', 'root.md'),
+        (2, 'bot', 6, 'reports', 'reports/audit.md'),
+        (3, 'bot', 6, 'seo/coderank', 'seo/coderank/crawl.py'),
+        (4, 'bot', 5, 'reports', 'reports/other.md'),
+        (5, 'workspace', 2, 'shared', 'shared/doc.md')`,
+);
+
+const scopes = [{ scope: "bot", owner_id: 6 }];
+
+describe("a conversation's file list", () => {
+    test("the top level alone misses every file a bot saved in a folder", () => {
+        expect(rows({ db, scopes, recursive: false })).toEqual([1]);
+    });
+
+    test("the whole tree has them all, so a nested file ref resolves", () => {
+        expect(rows({ db, scopes, recursive: true })).toEqual([1, 2, 3]);
+    });
+
+    test("another owner's folder is never in it", () => {
+        expect(rows({ db, scopes, recursive: true })).not.toContain(4);
+    });
+});

src/functions/backend/db/bot-files/grab-conversation-files.ts

@@ -19,6 +19,11 @@ type Params = {
  * (a workspace's shared one, else the bot's own), its latest
  * `AppData.BotFilesPageSize` of them, and the usage against the quota.
  * The full list (folders, search, older files) loads in the files modal.
+ *
+ * It takes the whole folder tree, not just its top level: a bot saves into
+ * paths like `reports/` or `seo/coderank/`, and a file chip in a message
+ * can only find the file it names among these, so a top-level-only list
+ * left every nested `[file:ID]` unclickable plain text in the chat.
  */
 export default async function grabConversationFiles({
     bot_id,
@@ -29,7 +34,7 @@ export default async function grabConversationFiles({
         : ({ scope: "bot", owner_id: Number(bot_id) } as const);
 
     const [files, usage, quota_bytes, quota_mb] = await Promise.all([
-        listBotFiles({ scopes: [scope], limit: AppData.BotFilesPageSize }),
+        listBotFiles({ scopes: [scope], recursive: true, limit: AppData.BotFilesPageSize }),
         grabStorageUsage(scope),
         grabBotFileQuotaBytes(),
         grabBotFileQuotaMb(),