Re-submission of #1625 (which was merged early, then reverted in #1626)
— now with **all three round-1 reviews addressed** so it lands in one
hardened state instead of as post-merge follow-ups.
## What
Per-node **Reach** view: a standalone page (`#/nodes/{pubkey}/reach`) +
a node-detail section + `GET /api/nodes/{pubkey}/reach`. It shows which
nodes a node has a **stable two-way RF link** with, derived from raw
`path_json` adjacency (a path travels origin→observer, so `[A,B]` ⇒ B
heard A). A link is bidirectional when both directions have
observations; the **bottleneck** (weaker direction) rates two-way
reliability. Nodes are identified only by **unique 2–3 byte** path
prefixes (1-byte collides → excluded).
## Review fixes folded in vs #1625
**Performance (Carmack):** hard scan LIMIT (200k) + modest prealloc;
`json.Unmarshal` replaced by a single-pass `parsePathTokens` (100k-row
scan 2.2M→1.3M allocs, 344→203ms); memoized resolver; size-hinted maps
(attribution over 100k rows: 102 allocs); `context.Context` plumbed;
cache `RWMutex` + evict-oldest (no full wipe); singleflight dedup;
degree/rank from a 60s shared snapshot; bench rewritten (ReportAllocs,
1k/10k/100k, mixed-payload, isolated attribution).
**Correctness/safety + tests (Independent + Kent Beck):** pubkey
validation → 400; error logging instead of silent swallow (first_seen /
degree / marshal→500 / discarded rows); `public_key=?` index use;
canonical `PayloadADVERT`; `min()` builtin; documented cache-slice
immutability; mux ordering comment. New tests: scanReachRows decode,
3-byte token branch, non-advert first-hop guard, observer SNR
aggregation across rows, HTTP-level attribution (asserts non-zero
we_hear/they_hear), 400/404/blacklist/cache-hit.
**UI / a11y / Tufte:** in-map legend (tiers + thresholds); dropped the
colour+width double-encoding (constant width, colour-only); colour-blind
glyphs (●●●/●●/●) + tier title beside the bottleneck number; dark-theme
`--link-*`; lighter table (horizontal rules, sentence-case headers); map
built once + link layer updated in place on toggle (no flicker);
time-range no longer flashes a loader; `destroy()` generation guard;
statCard escaping; scoped `@media print` to `#nq-report`;
`fieldset/legend` + `for/id` toggles; `aria-pressed` / `aria-live` /
back-link `aria-label`; "distance (km)" + bottleneck tooltip + no-GPS
note; inline styles → CSS; decorative emoji removed.
**Docs:** api-spec documents the 5-min cache, 200k scan cap, and 400.
## Testing
- `cmd/server` full suite green; reach unit + endpoint + bench all pass.
- `eslint public/*.js` (no-undef) and the XSS-sink gate clean.
- E2E updated: request status checks + exact (non-tautological) toggle
assertions + hard map-render assert.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---
## TDD-history note (Kent Beck gate)
This branch carries production + tests together, not a fabricated
red→green sequence. That's deliberate: the branch was rebased onto
upstream and the intermediate SHAs were squashed, so reconstructing a
"failing-test-first" commit after the fact would be theatre, not
evidence — and rewriting history to stage it would be dishonest. The
behaviour is instead covered by a comprehensive, anti-tautological suite
(directional attribution edges, 3-byte token branch, non-advert
first-hop guard, observer SNR aggregation, HTTP-level attribution
asserting non-zero counts, scan-cap truncation, zero-reach 200-not-404,
companion mis-attribution, cache eviction). Requesting maintainer
acceptance of the work on test *substance* rather than commit
*choreography*; the net-new-UI exemption is not claimed for the server
endpoint.
---------
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: meshcore-bot <bot@meshcore>
Reverts #1625.
#1625 was merged before the round-1 reviews (Independent / Kent Beck /
Tufte) were addressed. Reverting to land it cleanly: a fresh PR will
re-add the feature with the perf pass, the backend correctness/safety +
test-coverage fixes, and the UI/a11y (Tufte) batch folded in, so it goes
through review in a single hardened state rather than as a string of
post-merge follow-ups.
No functional loss — the feature returns in the replacement PR.
## What
Adds a per-node **Reach** view that answers "how well does this specific
node hear, and get heard by, its neighbours?" — both as a standalone
page (`#/nodes/{pubkey}/reach`) and as a section on the node detail
page.
New endpoint: **`GET /api/nodes/{pubkey}/reach`**.
## What it measures
For the target node it derives, from raw `path_json` adjacency (a path
travels origin→observer, so in `[A,B]` B received A directly):
- **Directional link counts** per neighbour: `we_hear` (how often we
received them) vs `they_hear` (how often they received us).
- **Bidirectional / bottleneck**: a link is two-way stable when both
directions > 0; the weaker direction is the bottleneck and rates real
two-way reliability.
- **Importance**: neighbour degree + rank, relay-observation volume,
bidirectional-link count, direct-observer count.
- **Direct observers**: who received the node at 0 hops, with SNR.
Reliability rule: a neighbour is only attributed when its pubkey
**prefix is unique** at the path's byte length (collisions are skipped,
never misattributed).
## UI
- Standalone Reach page + node-detail section.
- Reusable bidirectional link map (OSM) with links coloured by
bottleneck.
- Incoming/outgoing toggles to isolate each direction.
## Naming note (deliberate, no collision)
This is distinct from the existing **per-observer reachability** in
topology analytics (`ReachNode` / `ObserverReach` / `perObserverReach`).
This PR adds its own `NodeReach*` response structs in a new
`node_reach.go` and a new `/api/nodes/{pubkey}/reach` route — there are
no symbol or route collisions (verified: `go build ./...` clean). Happy
to rename to disambiguate further (e.g. "Link Quality") if you'd prefer
to reserve "Reach" for the per-observer feature.
## Testing
- `cmd/server`: endpoint shape/404/limit-clamp + unit tests for token
derivation and directional attribution, plus a scan benchmark — all
pass.
- Frontend: helper tests + Reach-page E2E (`test-node-reach-e2e.js`),
standalone route + incoming/outgoing toggles.
- `go build ./...` and `eslint public/*.js` (no-undef) clean.
## Docs
Design spec, implementation plan, and the `GET
/api/nodes/{pubkey}/reach` API contract are included under `docs/`.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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