Beagle SCM

DIFF-003: file-scoped diff: shows the whole file, changes highlighted

A hunk nav-URI like diff:ast/BAST.c#L362 (the U link bro emits on each diff hunk) currently opens a FILE-SCOPED diff: that shows only that file's changed hunks, scrolled to the line. For a single file the user wants the opposite of the dir/tree view: render the WHOLE file content with the changed lines highlighted in place (like git diff --color over the full file, a review pane), so a change reads in full surrounding context. Tree/dir diff: keeps showing only changed hunks. Method: Issues.

Input

Context

• diff: is URI-driven (graf/DIFFREF.c: "file or whole tree, ref vs wt or ref vs ref"). A file path scopes to that file; today it emits only the file's changed hunks.
• bro emits a U nav-URI per hunk carrying a #L<n> line anchor (dog/HUNK.c fragment grammar; built via HUNKu8sMakeURI, graf/WEAVE.c). Clicking it re-dispatches diff:<path>#L<n> — the entry point for this view.
• Distinct from dir/tree diff: (changed-hunks-only), which must NOT change.

Goals

• be diff:<file>#L<n> (file-scoped) renders the FULL file, every line, with added/removed/changed lines highlighted in place and the #L<n> anchor honored for scroll/jump.
• Tree/dir-scoped diff: (no single-file path) stays changed-hunks-only.
• Works in Plain/Color/TLV; composes the same under sub recursion.

Constraints

• Producer/renderer split: graf decides the EMIT scope (full-file lines vs changed-hunks-only) keyed off file-vs-tree URI scope; bro owns the change highlighting/presentation — producers must not decide presentation.
• No new diff engine — reuse graf's existing file diff (graf/DIFFREF.c, graf/WEAVE.c); emit unchanged context lines tagged so bro highlights.
• abc/ untouched; read-only dog/HUNK stream; all four URI slots compose.

WIP

Design decisions (open — confirm in a design pass before forking)

• Where full-file scope is decided: a file-scoped diff: URI should make DIFFREF emit all file lines (change-tagged), not just hunks — confirm the branch/flag, and whether the ref-vs-ref line cap must lift for one file.
• Highlight encoding: which dog/HUNK tok tags bro already has for add/del/ change lines, and whether full-file context needs an "unchanged" tag.

TODOs

• Design pass: confirm the DIFFREF file-scope branch + bro's tok tagging.
• Implement full-file emit for a file-scoped diff:; keep tree/dir scope changed-hunks-only.
• Honor the #L<n> anchor for jump/scroll in the full-file view.
• Tests: file-scoped diff:<file>#L<n> output contains an UNCHANGED line far from any change AND the highlighted changed line, in Plain/Color/TLV; tree-scope diff: still hunks-only (regression).

Blockers and bummers

• Whole-file emit on a huge file ⇒ large output; the per-file line cap may need a file-scope override (verify the BNOROOM-class limits).

Outcome

• Landed eaa75793: file-scope diff: reuses the cat: emitter WEAVEEmitFull (change-tagged, no windowing) via a b8 full flag threaded through GRAFDiff2Layer; tree-scope keeps windowed WEAVEEmitDiff.
• WEAVEEmitFull gained a scheme param so dog/HUNK routes the full-file hunk to the unified +/- formatter (cat: passes empty → byte-identical). Test test/diff/11-file-scope-full; 373/373 green.