FUG-83: derive AP SSID + mDNS/DHCP hostname from the configured device name

[issuefleet]

What

The device name the user configures now drives the soft-AP SSID and the
device hostname, as requested in FUG-83.

• AP SSID → <name>-AP (was hardcoded ledmapper). SSIDs allow spaces, so
  the display name is used verbatim, capped to the 32-byte SSID limit.
• Hostname → a DNS-label-safe slug of the name, so <name>.local resolves
  over mDNS. Slugging keeps [A-Za-z0-9], collapses any other run to a single
  -, and trims — e.g. Led Widget A1B2C3 → Led-Widget-A1B2C3, and a simple
  TestWidget stays TestWidget. Empty/all-symbol names fall back to
  ledmapper.

So a device named TestWidget advertises the TestWidget-AP soft-AP and
answers to TestWidget.local, matching the issue's example.

How

• Brought up the IDF mDNS responder (mdns_init + mdns_hostname_set +
  mdns_instance_name_set with the friendly display name + a lightweight
  _http._tcp service) so <name>.local resolves on both the STA and soft-AP
  interfaces. The espressif__mdns component is already in the SDK.
• Set the STA and soft-AP DHCP hostnames (WiFi.setHostname /
  WiFi.softAPsetHostname) so the router/DHCP leases also show the name.
• The wss cert SAN now carries <name>.local (instead of the previously
  hardcoded ledmapper.local) so https://<name>.local validates.
• Live rename (set_device_name → poll_device_rename) recomputes the
  SSID + hostname, reconfigures the soft-AP (while it's still up), re-points the
  mDNS hostname/instance, and forces a cert re-issue so the new .local lands
  in the SAN.
• setup() is reordered so the device name is resolved before WiFi comes up
  (the SSID + hostname must be known at WiFi.mode/softAP/begin time);
  g_cert_ip moved up so the rename path can reset it.

Verification

• bazel build -c opt //firmware/player_app:esp32c6 — passes, produces
  esp32c6.bin. This is the real gate: it confirms the mDNS component both
  compiles (header + matching signatures) and links into the image
  (-lespressif__mdns is in the SDK's link recipe; the symbols resolve).
• Static check of the fetched SDK confirmed the WiFi hostname APIs and the four
  mDNS functions exist with the signatures used.

Not yet exercised on real hardware (no HITL access from this worktree);
suggest a quick DUT check that the AP shows as <name>-AP and <name>.local
resolves after a join + after a rename.

Notes

mDNS adds a small always-resident cost. The device already tears the soft-AP
down after a LAN join to free heap for the ~17 KB TLS handshake buffer; the
mDNS responder is comparatively light, but worth watching on a real DUT that
the wss handshake still has headroom.

Closes-Linear: FUG-83 (https://linear.app/fughilli/issue/FUG-83/ap-name-and-hostname-should-match-configured-name)

[linear-code]

FUG-83 AP name and hostname should match configured name

When the user configures the device name, that name should also be used for the AP and the hostname (for mDNS).

E.g. if the device name is TestWidget, the AP should be TestWidget-AP and the hostname should be TestWidget.local.

Review in Linear

[github-actions]

PR Preview Action v1.8.1
Preview removed because the pull request was closed.
2026-08-07 04:45 UTC