Complete Phase 12 dual-stack networking

Add IPv6-aware Wi-Fi state, HTTPS/SSH listeners, mDNS service
reconciliation, and browser Wi-Fi administration.

Include a guarded build-local fix for mDNS 1.12.0 membership handling,
focused regression suites, and Phase 12 acceptance documentation.

docs/roadmap.md

@@ -41,8 +41,7 @@ These constraints apply across all phases:
 | 8 | Role-based users and administrative access | **Complete** |
 | 9 | Small intermittent-use security baseline | **Complete (user signoff 2026-09-18; new hardware check waived)** |
 | 10 | Simple admin web firmware upload | **Complete (explicit user acceptance 2026-09-18; upload and normal operation verified)** |
-
-| 12 | Advanced network integration | **Under evaluation** |
+| 12 | Dual-stack networking and local service discovery | **Complete (explicit user validation; fresh boot and full client mix at 230400 baud)** |
 
 
 ## Completed phases
@@ -293,11 +292,11 @@ These are reusable checks, **not recorded passes or outstanding acceptance gates
 
 ## Current and planned phases
 
-**Phases 8, 9 and 10 are complete** for their accepted scopes. Phase 9 includes the explicit new-hardware-check waiver above; Phase 10 includes explicit user acceptance of upload and normal operation. Remaining future work is under evaluation. Optional features must not weaken completed serial and recovery paths. General release gates below guide future work, not claims that every fault, soak, recovery or reserve measurement was performed for completed phases.
+**Phases 8, 9, 10 and 12 are complete** for their accepted scopes. Phase 9 includes the explicit new-hardware-check waiver above; Phase 10 includes explicit user acceptance of upload and normal operation. Phase 12 includes explicit user validation and the fresh-boot/full-client evidence below. Optional features must not weaken completed serial and recovery paths. General release gates below guide future work, not claims that every fault, soak, recovery or reserve measurement was performed for completed phases.
 
 ### Phase 12 — Advanced network integration
 
-Agreed planning baseline; implementation is not yet authorized:
+**Complete by explicit user validation:** “I just validated Phase 12 successfully.” Accepted baseline:
 
 - Dual-stack local access and DNS-SD discovery: advertise available HTTPS and SSH services using the shared `sak-<suffix>.local` hostname, with appropriate IPv4 `A` and IPv6 `AAAA` records. Preserve IPv4 access and verify IPv6 support throughout HTTPS, WebSocket and SSH. Clients choose address-family preference and fallback; DNS-SD cannot mandate IPv6 preference. Certificate-name integration and trust remain separate concerns.
 - Send the configured device hostname (`sak-<suffix>`, without `.local`) through DHCPv4 Host Name option 12 so a suitably configured DHCP/DNS server can publish the lease address in its own DNS zone. Set the STA netif hostname before DHCP starts, define how hostname changes reach subsequent DHCP exchanges, and verify the transmitted option and server-side DNS registration. DNS publication and the DNS domain remain server policy; mDNS does not provide this integration.
@@ -306,6 +305,64 @@ Agreed planning baseline; implementation is not yet authorized:
 
 The device is not intended to become a general-purpose router. Captive-portal interception, unauthenticated DNS redirection, NAPT, and a plaintext serial listener remain out of scope unless the project requirements are explicitly revised.
 
+#### Implementation and operational boundaries
+
+- The Wi-Fi owner installs the full configured hostname before STA connection and updates it after hostname edits. DHCPv4 option 12 uses `sak-<suffix>`, not `.local`. Rename does not force DHCP restart: the next DHCP exchange carries the new name, and DNS registration/cache cleanup remain server policy. Existing hostname limits and NVS formats are unchanged.
+- STA enables SLAAC and IPv6 link-local creation; either IPv4 or a preferred IPv6 address establishes `ONLINE`. **Link-local-only counts as online**, prevents IPv4-only timeout/failover, and can retire the fallback AP after the existing stability interval. This indicates local address availability, not Internet reachability or a default route. Web, CLI and OLED distinguish absent IPv4 from IPv6 availability. A diagnostic follow-up adds up to three preferred numeric IPv6 addresses to the snapshot, copied and cleared with the same observation; `wifi status` and browser Network settings print them in link-local/ULA/GUA groups; overview/OLED status retains availability flags. The settings JSON is bounded to 2304 bytes, with no extra netif calls on HTTPD.
+- HTTPS/WebSocket use IDF's existing dual-stack listener. SSH explicitly uses one dual-stack listener, retaining the existing two-session limit. Bracketed IPv6 HTTPS authorities are canonicalized and bound to the existing Host/Origin/session checks; scoped IPv6 literal URLs are rejected. Prefer the `.local` hostname for link-local browser access, subject to client resolver support. No certificate regeneration, new trust mechanism, or automatic IPv6 preference is introduced.
+- STA-only mDNS advertises `_https._tcp:443` and `_ssh._tcp:22` according to listener availability, without TXT metadata. Record and address-family changes converge through the existing Wi-Fi owner, including offline reconciliation; service setters do no component work. The responder is not restarted for ordinary changes. Initialization failure remains latched/nonfatal.
+- mDNS 1.12.0 exposes no readiness acknowledgement and can silently drop queued family actions. Absent families are disabled on each one-second owner pass; available families are re-enabled/reprobed on a 30-second repair cadence. Upstream synchronous calls can delay this cadence. There can be a transient stale/zero-A response window after IPv4 loss before disable is processed. AAAA records follow upstream **valid-address** semantics, including deprecated-but-still-valid addresses, not preferred-only filtering. Client caches expire independently.
+- `cmake/mdns_membership.*` applies one version/hash-guarded, build-local source overlay to mDNS 1.12.0: balance per-family multicast leaves and unwind joins after PCB creation failure. Managed sources and dependency versions remain unchanged. An upstream mismatch fails configuration for deliberate review; see `tests/mdns_membership/README.md` for maintenance/removal and regression evidence. This is not the abandoned Phase 9 patch set.
+- `sdkconfig.defaults` explicitly enables IPv4/IPv6 and increases mDNS service capacity from one to two. Existing saved configurations override defaults: verify `CONFIG_LWIP_IPV4=y`, `CONFIG_LWIP_IPV6=y`, `CONFIG_MDNS_MAX_SERVICES=2` and STA-only predefined mDNS interfaces before building. The local N16R8 saved configuration was updated accordingly. No new task, transport socket, broker slot, serial buffer, partition, filesystem or generated web asset was added.
+- Existing diagnostic limits remain: hostname ping selects the resolver's first usable result (not Happy Eyeballs), scoped link-local ping is not newly supported, and traceroute remains IPv4-only. DHCPv6, infrastructure DNS registration of SLAAC addresses, and new IPv6 resolver provisioning are outside this baseline.
+
+#### Validation evidence and acceptance
+
+`pio run` passed on PlatformIO 6.12.0 / ESP-IDF 5.5.0 with the guarded mDNS source compiled: **94,396 B linked RAM / 1,853,025 B flash**, +176 B RAM / +5,380 B flash versus the recorded Phase 10 build. These are static link sizes, not runtime heap or stack headroom. Initial target compilation rejected lock-free bool atomics; the implementation now uses short portMUX sections. Existing SDK Kconfig notes remain.
+
+Host checks passed: Wi-Fi/address/hostname reconciliation, mDNS lifecycle/family repair, actual patched multicast-membership functions and CMake guards, SSH dual-stack/management/runtime/security, HTTPS authority parser (689 cases on host and actual installed lwIP parser), cookie authorization variants, Network settings, browser UI/CSP (171 groups), HTTPS lifecycle (45 groups and eight status projections), firmware upload (88 cases plus SDK contract), broker diagnostics, and session-store/serial integration. Network-settings host fakes were updated after the new netif dependency exposed a compilation failure; the rerun passed. These are not packet-level or hardware evidence.
+
+Follow-up after the user's live status report: both preferred-address flags were `yes`, while plain client `ping` selected IPv4. Source verification confirms the flags require actual preferred addresses; this is not evidence of failed SLAAC or verified IPv6 reachability. `wifi status` now prints the addresses for diagnosis. Latest follow-up `pio run` passed: **94,444 B linked RAM / 1,853,685 B flash** (+48 / +660 versus the initial Phase 12 build). Browser Admin console now permits canonical Wi-Fi commands, including disruptive edits and hidden prompts, as explicitly requested. Focused policy/browser Wi-Fi prompt, address snapshot/rendering, Network/cookie and UI regressions passed. The broader console-boundary suite passes its console/certificate stages but has a pre-existing SSH-adapter fixture compilation failure for missing `web_firmware_update_reserve_reboot`; no production change was made to hide it.
+
+Latest address-display build: `pio run` **94,444 B linked RAM / 1,854,485 B flash**; Network API/owner checks and **174 browser groups plus CSP** passed. These remain build/host results, separate from the user's device evidence below.
+
+##### User-reported device acceptance
+
+User explicitly validated Phase 12 after confirming numeric IPv6 ping/HTTPS, Avahi AAAA resolution and normal IPv6 hostname access following the Fedora `authselect` mDNS correction. The earlier hostname failure was a client resolver configuration issue, not missing device IPv6 addresses. The acceptance capture adds:
+
+- **Fresh boot:** HTTPS, SSH and mDNS running without reported startup failures; zero SSH sessions, serial stopped, no broker clients, USB attached but not host-open. The configured UART profile is **230400 baud, 8N1, RTS/CTS, DTR active, RTS threshold 96**.
+- **Full client mix:** two authenticated public-key SSH sessions with IPv6 ULA peers (one serial observer, one admin console); two serial WebSockets (one writer, one observer); one active browser admin WebSocket; native USB host-open as an observer. Four broker clients, exactly one writer, all reported pending/event counts zero. Serial running with RX-available/TX-pending zero, CTS asserted and valid RS-232 voltage at observation time.
+- SSH: two successful handshakes, zero handshake/authentication failures or timeouts, zero stream I/O failures and zero session revocations. Stream counters **RX 68 / accepted 65 / rejected 3 / TX 161,209 bytes**; two broker writer revocations were reported. The rejected bytes are retained as evidence, not silently described as zero loss or assigned an unverified cause.
+- Web serial: two connections, **27 accepted RX frames/bytes**, zero rejected RX frames/bytes; **782 binary TX frames / 318,230 bytes**, 11 control frames / 948 bytes. Send/queue/protocol/close failure counters zero. Two writer requests were denied; the final broker snapshot still shows one writer. Browser admin: one connection, **106 RX / 3,721 TX bytes**, zero send/queue/protocol/authorization/backpressure failures. No response errors reported.
+- HTTPS and SSH both report running, not transitioning, `ESP_OK`; mDNS reports expected announcement and `ESP_OK`. Expected announcement alone is not packet-level service-record proof; the earlier successful Avahi lookup separately establishes the reported AAAA lookup.
+
+All heap figures are bytes, copied from the user's observations:
+
+| Observation | Heap capability | Free | Lifetime minimum-free | Largest block |
+|---|---|---:|---:|---:|
+| Fresh boot | Internal 8-bit | 65,880 | 64,912 | 31,744 |
+| Fresh boot | Internal DMA | 58,124 | 57,156 | 31,744 |
+| Fresh boot | External PSRAM | 8,196,732 | 8,187,980 | 8,126,464 |
+| Full client mix | Internal 8-bit | 35,408 | 8,528 | 22,528 |
+| Full client mix | Internal DMA | 27,652 | 772 | 22,528 |
+| Full client mix | External PSRAM | 8,111,952 | 8,072,612 | 7,995,392 |
+
+SSH owner stack: **20,480 B** configured, **18,476 B minimum-free** at fresh-boot observation and **16,284 B minimum-free** under the full mix.
+
+**Evidence limits:** minimum-free is the conservative sum of matching heap regions' lifetime minima, not a simultaneous free-space measurement or guaranteed allocation reserve. Internal 8-bit and DMA capabilities overlap and must not be added as independent pools. The **772 B DMA lifetime minimum remains a headroom watch item**, not an observed allocation failure or acceptance blocker. Boot output contains two TLS `-0x004C` receive errors and unauthenticated-request failures; the capture does not establish their cause or connect them to memory exhaustion. Command snapshots are non-atomic; differing cumulative request/authentication counts must not be treated as one aligned measurement interval. No UART overflow/per-observer drop counters, soak duration, byte-for-byte capture integrity, exhaustive fault injection, DHCP packet capture/server-zone update, or every address-family/service transition is established by this excerpt. User acceptance is recorded without inventing those passes.
+
+##### Reusable regression guidance
+
+The following procedures are retained for future regression testing, **not outstanding acceptance blockers or a claim that every item was executed**. Keep UART0 and USB recovery available:
+
+1. On IPv4, IPv6-only and dual-stack STA networks, exercise HTTPS login, serial/admin WebSockets, SSH user/admin access and one-writer/observer isolation. Test hostname access plus IPv4 and unscoped ULA/GUA IPv6 literals; verify SSH host keys and HTTPS identity rather than trusting discovery.
+2. Capture DHCP DISCOVER/REQUEST option 12 at boot, rename/renew and reconnect, including a maximum-length suffix. With a configured DHCP/DNS server, verify the resulting zone entry and its server-controlled update/removal behavior.
+3. Browse `_https._tcp` and `_ssh._tcp` and inspect A/AAAA/SRV answers over both families. Stop/restart each service; rename; drop/reacquire DHCP while IPv6 survives; change/deprecate/expire RA prefixes; disconnect/reconnect. Confirm eventual withdrawal/restoration, valid-address AAAA semantics and no persistent zero-A response. Exercise repeated family transitions and, where practical, missed-event/action repair.
+4. Check link-local-only readiness and the fallback-AP transition explicitly. Confirm the client preserves interface scope; do not infer browser link-local success from `ONLINE` alone. Test multicast filtering/AP isolation separately from firmware address readiness.
+5. Repeat the previously accepted 230400-baud mixed USB/WebSocket/SSH workload with discovery and address changes. Capture current/minimum internal, DMA and PSRAM availability, task stack margins, UART overflow and per-client drop counters. No new runtime memory reserve or maximum-baud performance guarantee is claimed.
+
+Phase 12 is complete by the explicit user validation above. This acceptance update changes documentation only; the agent did not run a new build, test, upload, erase or device operation.
+
 ## Cross-phase release gates
 
 Every phase should satisfy the following before being marked complete, with any user-waived check explicitly recorded in that phase rather than reported as passed: