Work the Project Sylpheed reverse-engineering backlog, one item at a time.

Read `Syplheed-Reborn/docker/agent/AGENT.md` first — it has the container's
tooling and, more importantly, the method rules this corpus is built on.

## Each iteration

1. **Pick one item.** Take the next open entry from
   `Syplheed-Reborn/docs/re/BACKLOG.md`, preferring the one whose "first step"
   is cheapest and most decisive. If you are mid-item from a previous
   iteration, continue it rather than starting another.
2. **Do the smallest experiment that could settle it**, and try to *refute*
   your hypothesis before you believe it.
3. **Write the result down** in `docs/re/` under the ✅/🟡/❔ convention, with
   the evidence. A withdrawn or refuted result is a real result — record it,
   with the reasoning, rather than deleting it.
4. **Commit** to a topic branch (below), one logical change per commit.
5. **Say plainly what you did not settle**, and stop the iteration.

## Hard rules

* **Never commit to `main`.** Work on `auto/<topic>` in whichever repo you are
  touching, branched from the current `main`. Create it if it does not exist.
* **Never push.** No push credentials are mounted, and that is deliberate — a
  human reviews before anything leaves the box.
* **One emulator at a time.** `run-canary` enforces this with a lockfile; do not
  work around it.
* **Do not edit `main`'s history**, do not rebase shared branches, and do not
  delete branches.
* **Measure the oracle; never infer it.** An iteration that reasons about the
  game without running it is a red flag unless it is a pure static-format task.
* **Verify with an artifact**, not with "it compiles": `build-reborn test` (it
  wires up `SYLPHEED_DISC` — without it the disc tests silently self-skip and a
  green run means almost nothing), `sylpheed-cli mesh render`, `screen render`,
  `save info`, a screenshot.

## When you are blocked

If an item needs something the container cannot do — hardware Vulkan for a
rendering question, a push, a decision only the user can make — **do not
improvise around it**. Write what you found, note the blocker in `BACKLOG.md`,
and move to the next item.

## Pacing

Self-pace. A useful iteration is one experiment plus its write-up, not a
marathon; stopping with a clean commit and an honest "here is what is still
open" is the goal every time.