feat: add bounded admin WebSocket backend (Phase 8D.5)

- Require current admin cookie sessions, Origin checks and single-use
  tickets
- Reuse the shared console with session-aware authorization and slot
  allocation
- Add HTTPD-owned I/O, bounded buffering and revocation cleanup
- Prevent LRU eviction of serial clients and stale admin socket closure
- Reject unsupported web-shell mutations before side effects
- Add host regressions, a smoke client and resource accounting

Validated by user sign-off after a 15-minute full-client soak at 230400
baud, with a few broker drops under heavy output. Browser UI remains
for Phase 8D.6; numeric memory reserves remain open.

docs/agent/current-state.md

@@ -4,6 +4,12 @@ This file is working memory. Update it during active work and before handoff; do
 
 ## Development state
 
+- **8D.5 validated by explicit user sign-off (2026-09-06):** User supplied settled cold-boot telemetry and reports successful **15-minute full-client-mix active-use soak at 230400 baud**, with a few broker drops under extremely fast/dmesg output, then explicitly closes 8D.5. Supersedes older pending/incomplete notes below. Boot internal/DMA/PSRAM free **70,876 / 63,120 / 8,246,360 B**, minima **59,560 / 51,804 / 8,242,140 B**, largest **31,744 / 31,744 / 8,126,464 B**; SSH stack minimum-free **18,472 B**. Admin initialized/attached with ESP_OK and 167/240/1,552 B static/ticket/payload accounting; no active clients at boot. Full mix/soak is user-reported, not evidenced by the idle snapshot; exact drop count/client, flashed revision and loaded/post-soak/cleanup telemetry not supplied. See `docs/phase8d5_implementation.md`. These limits do not reopen sign-off or imply zero-drop operation. Numeric reserves/runtime socket cost remain open. No new build/device/source action for sign-off. Wait for separate **8D.6** request; M2 not yet complete.
+
+- **8D.5 backend implemented / host-tested / build-verified (2026-09-06), target pending:** Preserved interrupted tickets/transport/server/shared-console/SSH/policy/revocation work and inherited test tooling. One admin socket, two tickets, existing two shared console slots, 1,552 B PSRAM-only payload, 20 ms ESP timer/no new task, six HTTPS sockets/no LRU eviction, 16 URI handlers. Added real cookie/store/ticket/transport endpoint integration tests. Final IDF lifecycle review found queued `httpd_sess_trigger_close` retains a reusable socket-slot pointer; changed the admin path to HTTPD-owned `shutdown`, with HTTPD read cleanup and retry/reuse regressions. Transport 19 groups + tickets 12, server lifecycle 11, combined endpoints, both console suites, store/serial, cookie/parser (268), login UI (8), serial UI (9) all pass; diff check passes. **Parent reports sequential final `pio run` after the shutdown fix passed in 23.55 s at 95,580 B RAM / 1,637,273 B flash: +416/+9,224 versus prerequisite, +496/+10,100 versus 8D.4, +1,048/+37,300 versus 8D.0.** This supersedes the continuation's earlier pre-fix build; history remains in the implementation record. Parent's final independent security integration reviewer reported no actionable findings. Target ELF payload/slot/ticket sizes 1,552/80/96 B, ticket state+lock 240 B, transport static symbols 167 B before padding, ESP timer internal allocation 32 B before heap overhead. See `docs/phase8d5_implementation.md` for exact commands, inherited-versus-final fixes, resource accounting, restrictions and manual target/client checklist. Client `--help` only exercised in the continuation; this final evidence update changed documentation only, with no source/tests/build/device/network/asset/UI/upload/commit action. **Stop before 8D.6; target acceptance, runtime socket cost, numeric reserves and M2 remain open.** This supersedes the prerequisite-only pause below.
+
+- **8D.5 prerequisite resumed / host-tested / build-verified (2026-09-06), target pending:** User requested continuation. Preserved existing uncommitted dispatcher/owner-currentness and prompt-cleanup changes in the console/SSH adapter; extended tests to production SSH snapshot/principal publication and wiping. Both console suites pass; independent production review found no actionable defects. `pio run` passes in **38.46 s**, **95,164 B RAM / 1,628,049 B flash** (**+80 / +876 B** versus recorded 8D.4); map confirms 80 B for two principal copies. No new tasks/routes/sockets/UI or backend yet. See `docs/phase8d5_implementation.md` for contract, scope split, test limits and target checklist. **8D.5/M2 incomplete.** Obtain target regression or explicit user decision before stacking live backend work. Exact next increment is still 8D.5 tickets/HTTPD-owned admin transport/protected admission/revocation/restrictions and integration checks, not 8D.6. Previous 8D.4/M1 sign-offs stand; numeric reserves remain open. This supersedes older wait-for-8D.5-request notes below.
+
 - **8D.4 validated by explicit user sign-off (2026-09-06):** User confirms successful empty Enter and soak testing and explicitly closes Phase 8D.4. This supersedes older pending/in-progress notes below, including the 8D.3 empty-Enter target retest. Boot/full-client-mix evidence and sign-off are in `docs/phase8d4_implementation.md`. Exact soak duration/revision, post-soak/cleanup telemetry and other detailed checklist results were not supplied; these are evidence limitations, not blockers to the user-approved closure or claims of execution. Numeric reserves remain open. No new build/device operation for sign-off. Wait for a separate **8D.5** request; no browser admin backend or M2 completion is claimed.
 
 - **8D.4 target validation in progress (2026-09-06):** User supplied clean-boot/full-client-mix UART0 evidence, recorded in `docs/phase8d4_implementation.md`. Loaded internal/DMA/PSRAM free **34,632 / 26,876 / 8,089,284 B**, minima **20,648 / 12,892 / 8,077,516 B**, largest **25,600 / 25,600 / 7,995,392 B**; SSH stack minimum-free **16,280 B** (boot **18,472 B**). Four broker clients at 115200 baud: SSH writer, USB and two web observers; user/admin SSH and both browser roles admitted successfully, no reported I/O/transport failures. One cumulative SSH broker revocation retained without diagnosis. Exact flashed revision/duration not supplied. Console-specific regressions, lifecycle/soak/cleanup and explicit phase sign-off remain pending; numeric reserves remain open. No 8D.5 request or implementation.
@@ -60,8 +66,8 @@ Based on checked-in source plus `README.md` and `docs/roadmap.md`:
 ## Clearly incomplete or transitional areas
 
 - Phase 8C hardware validation passed, including route separation, shared command serialization, history/completion, prompts, output backpressure, revocation during queued work, deferred SSH lifecycle/reboot actions, and full concurrent transport operation. At 460800 baud with SSH and WebSocket clients in parallel, substantial packet drops and slow display controls were observed under load, without memory exhaustion; no baud-rate reduction is planned.
-- Current HTTPS has no web-based user administration and gives both roles the same status/terminal routes.
-- Browser authentication now uses cookie login/logout without Basic fallback. M1 target checkpoint is signed off; browser administrative routes remain future separately requested M2 work.
+- Current shipped HTTPS UI gives both roles the same status/serial terminal. The 8D.5 admin backend is implemented without a UI entry; its temporary policy denies all user mutations and unsupported self-affecting lifecycle commands.
+- Browser authentication uses cookie login/logout without Basic fallback. M1 target checkpoint is signed off; 8D.5 is implemented, host-tested and build-verified, with target gates recorded above. Browser selector/lifecycle parity remain future separately requested 8D.6/8D.7 work, not completed M2.
 - NVS encryption, secure boot/flash encryption review, production certificate/provisioning policy, and OTA are not implemented. HTTPS login has a bounded global five-verifications/60-second throttle, not comprehensive cross-transport DoS protection.
 
 ## Known inconsistencies