Beagle SCM

GET-029: be get ?/proj baseline breaks on a bare-post wtlog tail

Surfaced during JS-025 worktree setup. be get file:<store>/.be/?/beagle (create a store-backed worktree) failed with "no baseline in .be/wtlog" because the store's wtlog HEAD was a post row carrying the sha in the FRAGMENT, while the baseline resolver reads only the QUERY slot. Worktree creation breaks whenever the last wtlog row is a bare post. Method: Issues.

Input

Context

• Repro: with a store whose latest wtlog row is post ?<branch>#<sha> (sha in #frag, empty query), be get file:<store>/.be/?/beagle aborts "no baseline in .be/wtlog". A sibling worktree's .be pointer (which had an explicit ?<sha> query) worked, confirming the slot mismatch.
• SNIFFAtCurTip / SNIFFAtQueryFirstSha resolve the baseline from the QUERY slot only; a post row puts the committed sha in the FRAGMENT.
• Hit by the JS-025 agent; worked around by copying a sibling .be pointer.

Goals

• be get baseline resolution falls back to a get/post/patch row's FRAGMENT sha when the query slot is empty, so fresh worktree creation works regardless of whether the wtlog tail is a get or a bare post.

Constraints

• Fix in the sniff baseline resolver (sniff/AT.c — SNIFFAtBaselineTreeSha / SNIFFAtCurTip / SNIFFAtQueryFirstSha); no manual parsing — use the URI lexer's fragment slot. Don't regress the query-slot path.

WIP

Design decisions

• (open) Prefer query sha when present (the explicit cur intent), else fall to the latest sha-bearing row's fragment. Mirror how be log/status read tips.

TODOs

• Repro-first: a toy store whose wtlog tail is a bare post, assert be get file:<store>/.be/?/proj succeeds (currently aborts). Red→green.
• Fix the resolver; re-run the get/post suites.

Blockers

• None.

Outcome

• CLOSED — subsumed by DIS-049 9e80e5f0 (2026-06-21): the "no baseline" on a bare-post/secondary-wt source was fixed within DIS-049 (secondary-wt source recognition + baseline reading the post-row fragment sha). test/get/55 covers exactly this shape. No separate fix needed.