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TeTeHackoandClaude Opus 5
97b6090344
## Summary `computeNodeHashSizeInfo` skips zero-hop direct adverts by **route type**. It should skip them by the **content of the path byte**, because the two cases are no longer the same thing. A zero-hop direct advert carries no path, so its hop count is 0. Whether the two size bits next to it mean anything depends on the sender: - Firmware that predates [meshcore-dev/MeshCore#3293](https://github.com/meshcore-dev/MeshCore/pull/3293) does `packet->path_len = 0` in `Mesh::sendZeroHop()`, wiping the whole byte including the size bits. `0x00` genuinely says nothing about the node's `path.hash.mode` — skipping it is right, and #649 was right. - A sender that writes the size through `setPathHashSizeAndCount()` emits `0x40` (2 bytes) or `0x80` (3 bytes) with a zero hop count. On a zero-hop packet nothing else can set those bits, so they are a deliberate declaration. #653 landed the skip as `pathByte & 0x3F == 0`, which swallows the second case too. The diagnosis in #649 had actually proposed `pathByte == 0x00`; the review widened it on the reasoning that a zero hop count always implies zeroed size bits. That was true in April, when no firmware wrote them. It is not true now. On the Czech mesh (869.4 MHz), a 24h window of 10k packets holds **54 zero-hop direct adverts: 39 at `0x00` and 15 carrying a declared size** (14× `0x40`, 1× `0x80`). ## Why it matters for display, not just tidiness Measured on one node over a 7-day window. A companion was reconfigured from a 2-byte to a 3-byte path hash. Its first advert under the new setting was a zero-hop direct one on **24 Aug 15:36 UTC** declaring `0x80`. That packet was dropped, so the node kept reading as 2-byte until its next **flood** advert arrived on **25 Aug 10:18 UTC** — 18h42m serving a configuration the analyzer had already been told was stale, confirmed against both an unpatched and a patched instance. With local adverts typically every 2h and flood adverts every 25h, that gap is the normal case rather than a corner one. It bites hardest on an instance whose retention window is shorter than a flood advert interval: there the node has *no* countable advert at all and falls out of `hash_size` entirely (which is what #1912 is about on the rendering side). ## Change `(pathByte & 0x3F) == 0` → `pathByte == 0x00`, in `computeNodeHashSizeInfo` and in `computeAnalyticsHashSizes` so the two views agree. `isZeroHop` renamed to `isUndeclaredZeroHop` in the latter, since that is now what it means. No complexity change — same single byte comparison inside the existing scan. ## Measured A/B Two builds of the **same commit**, one with the change, both run read-only against the same copy of a real 181k-transmission / 973-node database: | | baseline | patched | |---|---|---| | nodes changed | — | **1** | | nodes regressed | — | **0** | | `hash_size_inconsistent` | 6 | **6** | | `multi_byte_status` split | 726 / 161 / 86 | unchanged | The flip-flop flag not moving is the point worth checking: a node that legitimately changes its mode mid-window is still handled by the recency decay from #1788, so reading these packets does not resurrect false "varies". ## Tests `cd cmd/server && go test ./...` → **ok**, 0 failures. Coverage 83.5%, unchanged from master. 5 new cases in `cmd/server/zerohop_hashsize_test.go`, two built from real off-air packets: - zero-hop DIRECT `0x40` → `HashSize 2` (was: dropped) - zero-hop DIRECT `0x80` → `HashSize 3` - zero-hop DIRECT `0x00` → still absent from the map, i.e. #649's behaviour preserved - TRANSPORT_DIRECT at path-byte offset 5, declared vs wiped - the declared size reaching `computeMultiByteCapability` as `confirmed`, which is what the map's multi-byte overlay reads **One existing test changed, flagging it explicitly:** `TestHashSizeTransportDirectZeroHopSkipped` used `0x40` as its "should be skipped" fixture. It now uses `0x00` — the case it was written to cover, since #747 was about the missing `RouteTransportDirect` skip rather than about the size bits. The `0x40` case is covered by the new tests with the opposite expectation. ## Deliberately not touched The decoders (`cmd/server/decoder.go:648`, `cmd/ingestor/decoder.go:1045`) still report `HashSize 0` for these packets, so per-packet views keep showing the size as unknown. Arguably they should follow the same rule, but that changes packet display rather than node attribution and felt like a separate call for you to make. ## Caveat worth stating This attributes a declared size to the pubkey inside the advert. That holds as long as the advert was transmitted by the node that owns it — the same assumption the existing zero-hop **flood** path already makes, so this change does not widen it. Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>