feat: harden node placement and partial model loading

.scratch/alpha-hardening/runbooks/04-toploc-calibration-run.md

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+# Runbook 04 — Honest-noise TOPLOC calibration (issue 21)
+
+**Status:** engineering complete; **operator action required** before production audit thresholds.
+
+**Blocks:** enabling calibrated TOPLOC thresholds on a mainnet / friends-test fleet (issue 21, ADR-0018).
+
+## When to run
+
+- Before first real-money traffic with audit enforcement enabled.
+- Again whenever the fleet’s **hardware mix** changes materially (new GPU generation, CPU-only nodes added, precision/recipe change per model).
+
+Alpha exception: with a **small hired-VPS-only** fleet, `gate_status.ready` may mean “covers every node we operate today” (`--toploc-calibration-gate-min-hardware-profiles 1`).
+
+## Prerequisites
+
+- Tracker running with billing + registry + `--toploc-calibration-db PATH` (or default under tracker cwd).
+- At least one **solo-capable** node per hardware profile you want in the corpus (full model coverage — partial shards are skipped).
+- Admin or validator credentials (`Authorization` header or validator service token per ADR-0017).
+- Reference validator can replay the fixed calibration prompt (same model/seed as dispatch uses).
+
+## Steps
+
+1. **Register the fleet** — all nodes you intend to pay on mainnet should be up, admitted (NCA when enabled), and solo-serving the calibration model.
+
+2. **Dispatch the job** (admin/validator only):
+
+   ```bash
+   curl -X POST "https://<tracker>/v1/calibration/toploc/run" \
+     -H "Authorization: Bearer <admin-or-validator-token>" \
+     -H "Content-Type: application/json" \
+     -d '{}'
+   ```
+
+   Partial-shard nodes appear under `skipped_partial_shard_node_ids`. Per-node failures appear under `skipped` with reasons.
+
+3. **Wait for completion** — watch tracker logs and node consoles until every solo-capable node has a row in the corpus.
+
+4. **Fetch results**:
+
+   ```bash
+   curl "https://<tracker>/v1/calibration/toploc/results" \
+     -H "Authorization: Bearer <admin-or-validator-token>"
+   ```
+
+   Record:
+   - `envelope` — p99 metrics + 20% safety margin (recommended tolerances).
+   - `gate_status.ready` and `gate_status.hardware_profiles`.
+   - `estimated_false_positive_rate` (in-sample sanity check only).
+
+5. **Write up thresholds** — paste envelope values into operator notes / issue 21 comment. Do **not** wire into production `ToplocAuditConfig` until you have reviewed FPR on this fleet.
+
+6. **Mark issue 21 done** — when corpus covers the launch fleet and thresholds are documented.
+
+## Two-wallet / minimal pilot variant
+
+If your “fleet” is one node machine + one client:
+
+- Run calibration against the **node** profile only (one hardware row is enough for `gate_status` with min profiles = 1).
+- Client wallet is irrelevant to calibration — it never serves inference.
+
+## Do not
+
+- Enable stricter production audit thresholds before this completes.
+- Reuse a corpus collected on devnet/mock hardware for a different mainnet GPU mix without re-running.
+
+## References
+
+- Issue: `.scratch/alpha-hardening/issues/21-honest-noise-calibration-corpus.md`
+- Code: `packages/tracker/meshnet_tracker/calibration.py`, `POST /v1/calibration/toploc/run`
+- Validator: `packages/validator/README.md` — TOPLOC audit contract