todo: one file per item, grouped by theme, with a generated index

TODO.md had reached 1050 lines and 72 open items across 28 sections, read mostly
on a phone. It is now a directory: todo/<theme>/<item>.md, one card per file, with
frontmatter carrying id, status, created date and order, and the prose body copied
across verbatim. TODO.md becomes a generated index (bun run todo:index).

Dates: where an item's prose stated one it is used; otherwise its old section's;
otherwise 2026-08-20, floored at the day before the split rather than invented.
date_source records which.

Shaped for a two-way Kanban board, filed as todo/tooling — a card is a file, id is
the identity, frontmatter is the machine's half and the body is the owner's.

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

todo/plugin-system/a-plugin-cannot-declare-its-own-npm.md

@@ -0,0 +1,28 @@
+---
+id: plugin-system/a-plugin-cannot-declare-its-own-npm
+title: "A plugin cannot declare its own npm dependencies, so the PLATFORM is carrying them"
+theme: plugin-system
+status: open
+created: 2026-08-18
+date_source: section
+order: 1
+---
+
+**A plugin cannot declare its own npm dependencies, so the PLATFORM is carrying them.** `imapflow`,
+`mailparser` and `@types/mailparser` are in the platform's `package.json` and are imported by nothing
+in `src/` — they exist solely for `plugins/email/sidecar/`. Plugins have no `package.json`, run with
+`cwd: PLATFORM_DIR`, and resolve from the platform's `node_modules`, so deleting those three lines
+breaks the installed plugin on its first sync.
+
+This does not scale and it is the wrong party holding the risk: the platform cannot be answerable for
+what an arbitrary plugin decides to install, and `bunfig.toml` sets `frozenLockfile = true` precisely
+so a dependency change is a deliberate, reviewed act. Publishing will be reviewed rather than a
+free-for-all, which narrows the threat but does not move the responsibility.
+
+What it probably needs: a `dependencies` field in the manifest (the manifest already holds
+`osDependencies` for host binaries, which is the same shape of problem solved once), installed into
+the plugin's own directory at install time rather than merged into the platform's tree. Note the
+install path already learned not to trust `$PATH` — `pushPluginSchema` resolves a binary rather than
+spawning `bunx` — so whatever runs the install has to do the same.
+
+Until then: `imapflow` and `mailparser` STAY. Removing them is not tidying, it is breaking email.