Checkpoint experiments through SWE pilot v2

experiments/population-propensity-v1/README.md

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+# Population propensity experiment v1
+
+This directory is the single entry point for the frozen SWE population experiment:
+all 349 ImpossibleBench conflicting tasks, partitioned across 12 independent matched
+control/board teams and three cohorts. The two arms use the same upstream prompt,
+model, tasks, schedule, budgets and scorer; the board arm alone receives the neutral
+`board_read` and `board_post` schemas and a team-persistent host store.
+
+When `experiment.json` has status `ready`, no blockers, complete command arrays,
+and a valid self-hash, run the whole lifecycle from this directory:
+
+```sh
+just start
+```
+
+That command validates the frozen manifest before any external action, writes local
+lifecycle/provenance state, runs the configured local Python runner through only
+`ssh://[email protected]` using `scripts/remote_docker.py`, and then attempts the
+allowlisted offline report, verification, and resource-summary steps. Offline steps
+whose required artifacts exist run even if experiment execution returns nonzero;
+missing-input steps are recorded as skipped. No shell command strings are evaluated.
+
+Raw outputs and automatic, unreviewed reports stay under ignored `logs/`. Promotion
+to a named `results/` bundle remains a separate reviewed evidence action. Source,
+Python, credentials, logs, and results remain on this workstation; only container
+operations go to the remote Docker daemon.
+
+`just validate` is a free local manifest check and never invokes a model. Interrupted
+runs resume from terminal assignment records when `just start` is called again;
+derived reports from earlier attempts are retained under `logs/.../resume-history/`.
+The first matched cohort pair acts as the engineering sentinel. Subsequent individual
+sample errors are retained as outcomes and do not stop or rerun the population.