Beagle SCM

DIFF-013: bare jab diff ignores the cwd/nav dir context — whole-wt diff from a subdir

Input

Context

Reported by gritzko 2026-07-11, repro'd on the journal repo: jab diff run from ~/src/journal/wiki diffs the WHOLE journal tree; an explicit jab diff wiki scopes correctly (unlike status, whose arg leg is also broken — STATUS-006, same root class, fix the shared shape together).

• BE-048 ruled a no-arg VIEW verb inherits the context FILE as its subject, while a dir/authority-only context "stays whole-scope" (core/loop.js:390) — gritzko now extends the ruling: a DIR context must scope bare diff (and status) too.
• Bare diff being whole-wt was called BY DESIGN in BE-048; that design stands only for a context AT the tree root — a subdir cwd/nav context is a scope.

Goals

• Bare jab diff from a subdir (CLI cwd or pager nav context) diffs only that subtree; explicit diff <dir> behavior unchanged.

Constraints

• Repro test first (work); minimal diff; no edits to unrelated tests.
• ONE shared mechanism with STATUS-006 (context-dir default at the view edge or the loop edge), not per-verb copies.

WIP

Design decisions

TODOs

• repro test: bare diff from a subdir cwd emits only that subtree's difflets
• fix: context-dir default shared with STATUS-006
• pager leg verified: nav into a dir, bare :diff scopes to it

Blockers and bummers

Outcome