docs(journal): record explicit crawl group ids

docs/journals/260724-0935-crawl-explicit-group-ids.md

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+# Crawl Now Requires Explicit Group IDs
+
+---
+date: 2026-07-24 09:35
+session: crawl-explicit-group-ids
+---
+
+## Context
+
+`crawl.py` previously crawled every `group_id` stored in Redis configuration.
+The command now accepts its crawl targets explicitly so each run can select one
+or more groups without reconfiguring Redis.
+
+## What Happened
+
+- Added `argparse` parsing to `crawl.py` with `group_ids` as a required positional argument.
+- Changed `main()` to accept argv, parse IDs up front, and crawl only the supplied groups.
+- Kept session reuse in Redis intact; this was a contract change for crawl targets, not auth or storage.
+- Tests now cover multiple IDs, missing IDs, non-integer IDs, and the fact that configured `group_ids` are no longer used as an implicit fallback.
+
+## Verification
+
+`python -m unittest tests.test_crawl` passes. The test output shows the parser rejecting bad input as intended:
+
+```text
+python -m unittest: error: argument group_id: invalid int value: 'not-a-group'
+python -m unittest: error: the following arguments are required: group_id
+```
+
+The happy-path test verifies `crawl.main(['101', '202'])` calls `get_entity(101)` and `get_entity(202)` and never touches the configured fallback `999`.
+
+## Decisions
+
+- Require at least one group ID instead of retaining a zero-argument fallback.
+- Accept multiple positional IDs to support crawling several groups in one run.
+- Keep stored `group_ids` unchanged for commands such as `compare.py` that use
+  configured defaults.
+- Parse arguments before loading Redis configuration or constructing a Telegram
+  client, so invalid input fails without external contact.
+
+## Next Steps
+
+- Keep the README aligned with the new explicit-ID contract.
+- Add coverage for any future CLI that mixes stored defaults with runtime arguments, because that pattern already proved easy to get wrong.