tasks

.scratch/distributed-inference-network/issues/13-coverage-first-shard-assignment.md

@@ -47,3 +47,7 @@ Model preset metadata (stored in tracker config) includes `bytes_per_layer` at e
 - Rebalance directives are delivered as responses to node heartbeat POSTs (node polls tracker every 10s anyway) — no new push channel needed
 - `bytes_per_layer` is read from a `model_presets.json` config file; add GPT-2 (12 layers, ~30MB/layer bfloat16) as the test preset
 - The current tracker `_select_route` function is extended, not replaced — backward compat with stub nodes that don't send VRAM data (default to 8GB / bfloat16 if omitted)
+
+## Comments
+
+- 2026-06-30: Follow-up capacity hardening lives in `20-memory-budget-shard-slots-and-dropout-relocation.md`. US-013 remains the base coverage-first assignment and dropout rebalance story; US-020 owns operator `--memory`, `--max-shards`, shard-slot enforcement, and relocation limit hardening so the two scopes do not conflict.

.scratch/distributed-inference-network/issues/20-memory-budget-shard-slots-and-dropout-relocation.md

@@ -0,0 +1,65 @@
+Status: ready-for-agent
+
+# US-020 - Memory budget, shard slots, and dropout relocation hardening
+
+## Goal
+
+Make node capacity limits explicit and enforce them consistently when the tracker assigns, rebalances, and relocates shards after a node dropout.
+
+This is a follow-up to US-013, not a replacement. US-013 owns the coverage-first assignment and rebalance algorithm. This issue hardens the capacity contract around that algorithm: operator memory budget, maximum loaded shard slots, and relocation behavior when one node must absorb or split ranges after another node disappears.
+
+## Context
+
+Recent work added the first part of the contract:
+
+- `meshnet-node --memory MB` is registered with the tracker as `vram_bytes` when explicitly set.
+- CPU nodes without `--memory` keep the tracker default capacity, preserving old behavior.
+- `meshnet-node --max-shards N` is accepted and registered as `max_loaded_shards`.
+- Tracker registration validates `max_loaded_shards >= 1`.
+
+The current runtime still effectively has one active backend shard per node. A node may advertise `max_loaded_shards`, but the tracker does not yet use multiple shard slots in bin-packing, and the node does not yet host multiple concurrently loaded shard ranges.
+
+## Scope
+
+- Make tracker rebalance logic account for `max_loaded_shards` as a capacity multiplier or explicit shard-slot list.
+- Ensure a node is never assigned more total layers than its memory budget can support across all loaded shard slots.
+- Decide and implement the runtime behavior for multiple loaded shards:
+  - either support multiple concurrently loaded shard backends on one node, or
+  - keep one backend active and treat `max_loaded_shards` as future metadata, with tracker enforcement preventing multi-range assignment for now.
+- On heartbeat timeout, relocate the dropped node's uncovered layer range to eligible managed nodes while respecting both memory and shard-slot limits.
+- Surface the effective memory budget and shard slot count in tracker/network inspection output so operators can diagnose why a node did or did not receive a range.
+
+## Non-Goals
+
+- Do not redesign the US-013 coverage-first algorithm from scratch.
+- Do not change relay, `/ws`, or `/rpc` behavior.
+- Do not change the token/reward model.
+- Do not require public internet verification; all behavior must be locally testable.
+
+## Acceptance Criteria
+
+- Tracker stores and exposes `max_loaded_shards` for registered nodes.
+- Assignment/rebalance never exceeds:
+  - `assigned_layers_total <= floor((vram_bytes * 0.8) / bytes_per_layer_at_quant)`
+  - `assigned_range_count <= max_loaded_shards`
+- A managed node with `max_loaded_shards=1` only receives one active shard range.
+- A managed node with `max_loaded_shards=2` can absorb two non-contiguous uncovered ranges only if the node runtime supports serving both; otherwise tracker must keep assigning at most one range and document `max_loaded_shards` as reserved.
+- Dropout test: register nodes covering a model, let a middle/tail node heartbeat-expire, and assert the tracker queues `LOAD_SHARD` directives that restore full coverage without violating memory or shard-slot limits.
+- CLI test: `--memory` and `--max-shards` are reflected in the registration payload.
+- `python -m pytest tests/test_tracker_routing.py tests/test_node_startup.py` passes in the project virtualenv, aside from any pre-existing platform-specific wallet permission assertion documented in the final notes.
+
+## Implementation Notes
+
+- Existing files likely involved:
+  - `packages/node/meshnet_node/cli.py`
+  - `packages/node/meshnet_node/startup.py`
+  - `packages/node/meshnet_node/torch_server.py`
+  - `packages/tracker/meshnet_tracker/server.py`
+  - `tests/test_tracker_routing.py`
+  - `tests/test_node_startup.py`
+- Keep backward compatibility: nodes that omit `vram_bytes` default to tracker defaults; nodes that omit `max_loaded_shards` default to `1`.
+- Prefer a small internal representation for assigned ranges if multiple ranges become real, for example `assigned_shards: list[tuple[int, int]]`, while preserving `shard_start`/`shard_end` in public responses for single-range nodes.
+
+## Comments
+
+- 2026-06-30: Created after implementing the initial registration plumbing in commit `f1e4ed6` (`--memory`, `--max-shards`, tracker validation). This issue captures the remaining end-to-end behavior so it does not conflict with US-013.