# Read-support refs-v1; explain fetches a git-refs checkpoint on clone

`a1beae0`·

Soph·2w ago·15 files·+63 added/-35 removed

- checkpointpolicy: refs-v1 is now read- AND write-supported (refsV1Format added to both readFormats and writeFormats) so explain/resume/attach accept git-refs checkpoints and the git-refs store may write them. Tests that used "refs-v1" as a stand-in *unsupported* version now use "refs-v2" (the next, genuinely unsupported refs major); format_test asserts refs-v1 is supported.
- explain: on a fresh clone the prefix→ID remote fallback only fetched the v1 metadata branch (empty under git-refs). When the primary is git-refs and the prefix is a full checkpoint ID (the Entire-Checkpoint trailer always is), fetch that one ref via FetchCheckpointRef and re-list.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

## Sessions

291fe479c0a8View transcript

## Changes

15

- cmd/entire/cli

- Mattach_test.go+2/-2

- Mcheckpoint_policy_read_test.go+2/-2

- Mcheckpoint_policy_test.go+3/-3

- Mcheckpoint_policy_warning_test.go+2/-2

- checkpointpolicy

- Mformat.go+6/-1

- Mformat_test.go+3/-2

- Mpolicy_test.go+1/-1

- Mremote_test.go+4/-4

- Mstore_test.go+2/-2

- Mupdate_test.go+6/-6

- Mwarning_test.go+2/-2

- Mexplain_export.go+22

- Mexplain_export_test.go+3/-3

- Mexplain_test.go+3/-3

- Mresume_test.go+2/-2

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