Red commit: 94dc1d70a5Fixes#1574.
cross-stack: justified — by design. Adds one server-side knob
(`liveMap.maxNodes`) on the Go API and consumes it on the frontend
(`public/live.js`) via the shared `/api/config/client` bootstrap in
`public/roles.js`. Cannot land server-only or frontend-only without
either dropping operator config (frontend-only) or leaving the literal
in place (server-only).
## Problem (per triage)
`public/live.js:2515-2516` hardcodes `/api/nodes?limit=2000` for the
live-map node-load path. Reporter measured headroom at N=4300 and
asked for an operator knob. Same `2000` magic also lives at
`public/live.js:480` for the VCR-rewind `/api/packets?limit=2000`.
## Fix
- New `liveMap.maxNodes` field in `Config` (default 2000).
- `Config.LiveMapMaxNodes()` server-side clamp: `[100, 20000]`;
zero/negative falls back to default. Defangs misconfig (e.g. 1M
would OOM the SQLite read + JSON serialization path).
- `/api/config/client` now returns `liveMapMaxNodes`.
- `public/roles.js` reads it at bootstrap into
`window.LIVE_MAP_MAX_NODES`
(default 2000 to preserve behavior on stale caches).
- `public/live.js` consumes `LIVE_MAP_MAX_NODES` at both the
`/api/nodes`
call sites (formerly :2515-2516) and the VCR-rewind `/api/packets`
call (formerly :480) — single source of truth, in-scope per triage's
"factor into a sibling const" suggestion.
- `config.example.json` documents the knob with `_comment_maxNodes` per
AGENTS.md config rule.
## TDD
1. **Red** (`94dc1d70`): added `test-issue-1574-live-map-max-nodes.js`
(grep-asserts the literal is gone + `LIVE_MAP_MAX_NODES` /
`liveMapMaxNodes` are wired + config example has the field) and
`cmd/server/livemap_maxnodes_1574_test.go` (`/api/config/client`
exposes `liveMapMaxNodes` + clamp table-driven cases). Stub
`LiveMapMaxNodes()` returns 0 so the test compiles and fails on
assertion, not import.
2. **Green** (this commit): real `LiveMapMaxNodes()` clamp + wire-up.
All assertions pass; existing `cmd/server` suite still green.
## E2E note
Frontend assertion is grep-based (literal removal + constant
reference), in the established `test-issue-*` style used elsewhere
(e.g. `test-issue-1189-live-iata-badge.js`). No Playwright change
needed for a literal-replace; behavior validation is the server-side
clamp + JSON shape tests.
## Out of scope
No customizer UI change — operators set this in `config.json`, same
pattern as `liveMap.propagationBufferMs`. Customizer surfacing can
land as a follow-up if the operator wants it.
---------
Co-authored-by: mc-bot <bot@corescope.local>
Co-authored-by: Kpa-clawbot <bot@meshcore-analyzer>
Kpa-clawbot
1bdb92de88