Define staged Phase 8D delivery plan

docs/roadmap.md

@@ -198,7 +198,9 @@ Implementation sequence:
    - `ssh sessions` and `ssh counters` identify broker versus admin-console routes, worker command state, queued admin output, admission failures, and input backpressure. `exit` and Ctrl+D on an empty command line request bounded deferred self-disconnect after best-effort application-buffer draining. Admin sessions are checked for a current `admin` principal before command execution and during the active-session reconciliation.
    - Keep SFTP, SCP, `exec`, forwarding, subsystems, and unauthenticated shells disabled.
    - Target-hardware validation passed for route separation, history/Tab editing, interactive visible/hidden prompts, output/backpressure, generated and entered user/password/key management including the longest ECDSA P-256 import, ping event routing, deferred reboot/SSH lifecycle drain behavior, bootstrap/recovery rejection, targeted self/other-user revocation during queued work, UART0/SSH administration serialization, and concurrent USB/WebSocket/user-SSH/admin-SSH operation. Stress at 460800 baud with SSH and WebSocket clients caused substantial expected packet drops and slower display controls, but did not exhaust memory or require lowering the supported baud-rate range.
-4. **Phase 8D — Integrated web administration — Planned**
+4. **Phase 8D — Integrated web administration — Planned, staged delivery**
+   - **Execution plan:** [Phase 8D incremental plan](phase8d_plan.md). Implement one numbered chunk per request, with a build, focused regression checks, memory accounting, and a handoff before stopping. The requirements below describe the final scope, not one implementation task.
+   - **Milestones:** 8D.0–8D.3 establish a measured baseline and reliable login/logout with the existing serial UI; 8D.4–8D.7 add the shared browser admin shell and verify retained serial ownership; 8D.8–8D.21 add typed settings and contextual controls one domain at a time; 8D.22 performs final integration acceptance. Login and runtime-memory target validation gate the first two milestones; do not defer them until the entire phase is implemented. No wholesale import of the rolled-back experimental implementation.
    - Begin with integrated authentication: replace browser-facing HTTP Basic authentication with a same-origin HTTPS login page, explicit logout, and bounded opaque server-side sessions. Store only a digest of each random session token with a copied secret-free principal, expiry, CSRF state, and authentication-generation binding. Send the raw token only in a host-only `__Host-` cookie with `Secure`, `HttpOnly`, `SameSite=Strict`, `Path=/`, no `Domain`, and an explicit lifetime; never retain passwords, Basic headers, raw tokens, verifiers, or SSH-key blobs in snapshots or logs.
    - Make logout invalidate the current server-side session, expire its cookie, close that session's serial and administrative WebSockets, and redirect to login. Password/role/key mutation, deletion, recreation, and explicit revocation invalidate the affected account's web sessions and tickets without disturbing unrelated accounts. Require the CSRF token plus strict same-origin checks for every state-changing request, including logout, and rate-limit login attempts with bounded secret-free accounting.
    - Add an admin-only **Serial terminal**/**Admin shell** selector. The administrative route uses a short-lived, single-use, admin-principal-bound ticket and a bounded WebSocket frontend for the same serialized command registry used by UART0 and admin SSH; it is not a generic HTTP command-execution endpoint. Normal users retain the existing serial interface and cannot mint, upgrade, or invoke administrative routes. Remote policy still rejects physical-only `user bootstrap` and `user recover --force`.