# Phase 166.1-01 Summary

Status: implemented in working tree

## Goal

Make arXiv registration contentful-by-default so the concrete `L0`
source-acquisition handoff from Phase `166` no longer drops the operator into
metadata-only behavior, then close the milestone with one bounded fresh-topic
proof of `bootstrap -> handoff -> registration`.

## What Landed

- `register_arxiv_source.py` now defaults to content acquisition instead of
  metadata-only registration
- `--metadata-only` now exists as the explicit lightweight opt-out
- `--download-source` remains accepted as a compatibility-positive flag
- `discover_and_register.py` now inherits the same contentful-by-default
  semantics and exposes the same opt-out
- the first-run acceptance harness now supports a bounded registration
  continuation, explicit topic slug selection, and real-kernel execution
- operator docs now teach contentful registration as the normal path and
  `--metadata-only` as the exception
- one fresh topic slug,
  `jones-chapter-4-source-registration-proof-20260413`, now proves
  `bootstrap -> concrete handoff -> registration` on the real repository kernel
  root

## Verification

- `python -m pytest research/knowledge-hub/tests/test_source_discovery_contracts.py -q`
  - result: `13 passed`
- `python -m pytest research/knowledge-hub/tests/test_source_discovery_contracts.py research/knowledge-hub/tests/test_aitp_cli_e2e.py research/knowledge-hub/tests/test_runtime_scripts.py -q`
  - result: `105 passed`
- `python research/knowledge-hub/runtime/scripts/run_first_run_topic_acceptance.py --json`
  - result: passed on isolated temp kernel root
- real-kernel proof receipt:
  - `.planning/phases/166.1-contentful-source-registration-default/evidence/jones-chapter-4-source-registration-proof-20260413/proof.json`
  - result: `downloaded` + `extracted`

## Outcome

`REQ-L0HAND-03` and `REQ-VERIFY-01` are now satisfied:

- following the concrete Phase `166` handoff now lands on a useful default
  registration path
- the explicit lightweight path still exists through `--metadata-only`
- the milestone now has one bounded proof of
  `bootstrap -> handoff -> registration`

## Next Step

The active milestone `v1.92` is ready for `gsd-complete-milestone`.
