# P3-S25.1 — COMPUTE LIMITS AND FALLBACK

```text
2026-08-26 | Recovery #3 | Status: ENVIRONMENT/EXECUTION LIMITATION identified
```

## Observed compute limits

- Full read-only SHA-256 of the 34.5 GB source: **~153 s** (measured).
- A full-file monolithic `run()` (default 4,000,000-row chunks over the whole
  remaining file) exceeds the environment's per-session compute/wall-clock
  budget before reaching a durable checkpoint (per P3-S25 record).
- RAM: 36 GB free; Disk: 850 GB free — sufficient. Not resource-bound.

## Safe execution model (required)

```
ONE CHUNK -> VERIFY -> CHECKPOINT -> RETURN CONTROL
```
A single Python invocation must be bound to a small number of chunks
(constrain max_chunks), so the assistant regains control and writes a durable
checkpoint+recovery log frequently. No monolithic 34.5 GB command.

## Fallback subset strategy (authorized; NOT selected this session)

If repeated interruption is proven to be an environment limitation (as
indicated), the authorized deterministic subset may be used. Subset selection
must be **calender/coverage only** (calendar coverage; early/middle/recent;
P3-S20 overlap; weekend/session gaps; DST; representative tick density). It
must NOT be selected on setup outcomes or ML performance. If used, record
`p3_s251_subset_manifest.json` and classify honestly as
`SUBSET BASIS VALIDATED`, never `FULL BASIS VALIDATED`.

## Selection not performed this session

This session stopped at Stage A, so no subset manifest was written. Fallback
is available if a subsequent bounded resume attempt cannot run at least one
chunk per session.

*End of P3-S25.1 compute limits and fallback.*