docs(rfc): scope typed Driver Python and Fleet first delivery

[f-trycua]

Merge checkpoint - September 8, 2026

The broader proposal #2513 is merged as status: review, not accepted architecture. This PR lands only the separately accepted Python/Fleet first slice and its notice in the parent RFC. Runtime implementation, component publication, image packaging, and rollout remain separate steps.

The final diff remains two Markdown files (+269/-0). The update to main preserves their exact reviewed content; Prettier and diff whitespace checks pass. Earlier progress notes below describe their dated implementation checkpoints, not an additional authorization gate.

Scope

Phase A of the typed Driver integration stack, based on #2513. Refs #2512.

Preserves canonical generated CuaDriver methods across in-process and guest connections. Keeps MCP alongside typed application SDKs and shell/files/PTY/lifecycle outside Driver.

Accepted narrow slice

Maintainer decision: reuse Fleet's existing authenticated, namespace-authorized service route and private guest exposure. Do not introduce pairing, a guest credential issuer, or a claim-auth redesign. Treat stale sessions and runtime replacement as adapter lifecycle correctness.

The broader parent RFC remains in review. This acceptance does not authorize computer-server removal, public ingress, rollout, or merging.

Stack and progress

main -> #2513 -> this Phase A PR -> B1 receiver -> B2 carrier/bindings -> C Sandbox -> D local guest -> E agent -> F qualification -> G docs.

B1 receiver and the additive generated Python bridge are in development. No runtime implementation is released; no image publication, deployment, or merge into main was performed.

Validation

• Prettier 3.6.2 and git diff --check pass for both Markdown files.
• Python examples parse; they were not executed against a guest.
• Relative links resolve; source references pin audited main ddc7a63.
• Incremental public-disclosure and independent reviews completed.
• All applicable CI checks pass at 56fdcde.

Parent refresh

Synced current main into the historical parent RFC branch and then into this child with ordinary merge commits, preserving contributor history. No attribution configuration or check was edited. The incremental child diff remains two Markdown files; the parent diff remains its original RFC only.

Remaining evidence

Implementation tests, generated-library Python tests, authenticated guest integration, and exact-candidate desktop compatibility/cleanup evidence belong to the later stacked PRs. This documentation PR does not claim those checks passed.

[f-trycua]

Final Phase A validation at 5afd726: all applicable CI checks pass; the installer matrix is correctly skipped for this docs-only scope. Prettier, whitespace, example syntax, relative-link checks, disclosure review, and independent review also passed. The initial attribution failure was resolved by syncing current main into the parent RFC branch and then the child, preserving history and leaving attribution checks/configuration unchanged. No PR was merged into main, no runtime implementation or live provisioning was performed. Next gate remains the recorded RFC decision described in the supplement.