2b439e8a5f
Issue files (.scratch/issues/20-29): retrospective specs for all work done in the current sprint — hardening, route-timeout, start-layer protocol, heartbeat stats, availability map, rolling RPM, smart assignment, throughput routing, routing tests, relay outbound client. ADRs (docs/adr/0011-0014): 0011 — Auto-shard from memory budget and tracker network assignment 0012 — X-Meshnet-Start-Layer overlapping shard execution protocol 0013 — Rolling RPM statistics, smart assignment scoring, throughput routing 0014 — Relay outbound client for NAT/internet pipeline hops prd.json: US-020 through US-029 added, all marked done. ralph_progress.py now shows 29/29 complete (100%). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
30 lines
1.3 KiB
Markdown
30 lines
1.3 KiB
Markdown
# US-022 — X-Meshnet-Start-Layer: overlapping shard execution protocol
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Status: done
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Priority: High
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Stage: Implemented
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## Context
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Two nodes may register overlapping shard ranges (node A: 0–15, node B: 12–23) to increase
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redundancy or to enable partial-model nodes to form a complete route. Without coordination,
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node B would re-run layers 12–15 on top of activations that already include them, producing
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wrong output.
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The `X-Meshnet-Start-Layer` header tells each downstream node which model layer the incoming
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activation tensor represents, so the node skips layers it has already been told to skip.
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## Decision
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Option A: tracker injects `start_layer` into `X-Meshnet-Route` hops at proxy time. The head
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node passes it per-hop as `X-Meshnet-Start-Layer`. No peer-to-peer negotiation needed.
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## Acceptance criteria
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- [ ] Tracker `_handle_proxy_chat` builds route hops with `start_layer` = `covered_up_to + 1`
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- [ ] `_handle_binary_forward` reads `X-Meshnet-Start-Layer` and passes it to `backend.forward_bytes`
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- [ ] `_get_remaining_route` parses `start_layer` from injected header and from `/v1/route` slow-path
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- [ ] `TorchModelShard.forward_bytes` accepts optional `start_layer` and skips layers below it
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- [ ] Test: overlapping two-node route produces correct output without double-computing layers
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- [ ] `python -m pytest` passes
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