The parity record was pinned to upstream v0.49.1 and read as if the provider
settings descriptor already worked. Both are now wrong.

Add docs/research/2026-08-15-macos-parity-0.49.6.md, pinned to upstream v0.49.6
(0f66c32ecb69f35bccdd4e135cb0c7a6afd1dfb6) and probed against the installed CLI
0.49.6 rather than read from Swift sources. Update TODO.md and the AGENTS.md
mirror in the same change, as AGENTS.md requires.

Corrections the probes forced:

- config providers --descriptors returns "Unknown option --descriptors" AND the
  plain payload has no descriptor key at all. The contract is absent, not
  partially shipped, so the Providers descriptor path is dormant and degrades to
  enable/disable + set-api-key + links. TODO.md previously described it as
  consuming a "stable CLI settings descriptor", which invited someone to treat
  the dormant path as working.
- codexbar sessions --json-v2 is stable, returns bounded records, and has never
  been consumed. A local Agent Sessions list is not blocked; only remote/SSH
  focus is macOS-only. This was previously filed under blocked work.
- Quota warning thresholds are hardcoded at 80/95 in main.qml while macOS makes
  them configurable, and no CLI contract is involved. Newly recorded.
- Panel element composition lags the macOS draggable menu-bar chip layout, also
  with no CLI dependency. Newly recorded.
- The 69-provider catalog is re-verified against 0.49.6, which adds none.
- 0.49.2 through 0.49.6 shipped no new CLI JSON or settings contract; the
  provider data fixes reach Plasma by upgrading the CLI, not via QML.

make check passes.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>