Collapsed comparison view — partial native parity

Source: pinned TortoiseGit 7338078f8ddd924b8cddee35f512f2286072136d, DiffData.cpp::HideUnchangedSections, MainFrm.cpp::OnViewCollapsed and BaseView.cpp::OnLButtonDblClk.

The shared folding engine now implements source Shown/Hidden/Marker states, context processing, marker ranges, shared expansion and navigation reveal. Collapsed defaults to false; source ContextLines defaults to one and its saved DWORD -1 sentinel retains all context. Marker expansion affects the shared map for all panes. A pane-neutral projection retains source indices and explicitly marks placeholders; source documents are never rewritten by folding.

The native window controller holds saved collapse state, the synchronized projection, manual expansion, fresh alignment/context changes and retirement. Repeated hosting updates retain expansion until alignment or context changes. The two-pane/combined editors and three-pane source/result views now consume fold visibility through their attributed layout. Native View menus expose Collapsed. Full text/UTF-16 coordinates remain in text storage: hidden paragraphs use subpixel height, and the original marker row draws the source {...} and horizontal divider. Placeholder strings never replace document contents. Double-click expands source markers through the shared source controller. Find/Go To Line and other scroll-range requests reveal their destination before scrolling. Folding suppresses whitespace/inline ticks and ruler numbers on hidden/marker rows, and wrapping retains hidden-row heights.

The merge engine now emits exact common-row anchors into the initial result. Result presentation carries them through edits and Undo snapshots. An anchor shifts with preceding edits or is invalidated when its content is replaced; repeated text is never used to guess a replacement anchor. Result visibility projects the shared source map through those anchors. Result expansion reveals both source panes, and source expansion refreshes the result projection. If an edit removes a marker anchor, the surviving hidden result run receives an expandable marker. Changed/conflicted/edited result lines remain shown.

Native context menus and accessibility custom actions expose Expand unchanged section. Busy/preparing/retired owners refuse expansion. Find, Go To Line and scroll-range navigation reveal their target before native layout/scrolling.

The connected implementation is now at its grouped validation checkpoint: Core folding/result/engine/editing regressions, one Debug build, then one native folding/wrapping/two-pane/three-pane editor group. Physical input, VoiceOver, large-document performance, exact screen geometry versus Windows, and signed App Store acceptance remain open. The fallback non-Subversion alignment has no result anchors; its result stays visible rather than guessing positions.

The final Debug build and 39 focused Core checks passed. One grouped native receiver passed folding, wrapping and the existing two/three-pane editor families. The initial compile failed because the whitespace drawing helper referenced a text view outside its scope; it now reads attributes from its layout manager. The initial native fixture incorrectly required a newly prepared standalone merge to be clean. Its corrected assertion verifies unchanged initial dirty/Undo state. That fixture repair did not repeat the app build or Core suite.

The native checks measure actual TextKit collapse height, retain full view text, verify hidden navigation reveal in both panes, combined mode, exact engine anchors and synchronized expansion, busy/retired gates, accessibility action presence, both appearances and unchanged input bytes. Existing regressions cover wrapping/resize, Unicode typing/selection, Undo/Redo, marks, BOM/CRLF saves and merge Save/discard/Cancel/reload. Both owned receivers were reaped. Appearance switching and accessibility action presence do not prove visual matching or actual VoiceOver behavior. See validation evidence.

Atomic folding and aligned-result expansion — October 17, 2026

A multi-row reveal now mutates each folded run once and publishes one complete controller projection/expansion batch. TextKit fold application and restoration use editing transactions, so storage observers do not receive a half-restored or partially hidden map. Attribute restoration, original text coordinates and Undo semantics remain intact. Result-to-source expansion uses shared source row coordinates when the result has an aligned projection; serialized conflict-marker rows are used only through exact anchors in the free-result fallback. Source and result expansion now synchronize once per batch. Exact result anchor lookup uses an offset-to-row index instead of scanning every result line for every anchor.

The native folding receiver now mounts its own invisible windows before checking layout, matching production window attachment. It retains phase diagnostics for transactions, layout, selection, combined mode, anchored/aligned expansion, appearance and retirement. A timeout now prints bounded captured output tails before the existing owned-process cleanup and rethrows the original timeout. No timeout limit or behavioral assertion is relaxed. The earlier hosted timeout is still unresolved until the new hosted result supplies evidence; these changes do not establish its root cause.

The Debug build, all 23 focused Core checks and seven native-receiver ownership contracts pass. The eight-case grouped native pass covers folding, wrapping, wrapped navigation, block navigation, three-pane navigation, initial navigation, Find and viewport ownership. Atomic apply/restore each emit one complete editing notification; multi-run reveal publishes one projection/expansion batch. The native regression expands the aligned result after serialized conflict markers and verifies all matching source rows are shown without changing text, anchors, dirty or Undo. Core also verifies 12,000 exact UTF-16 row anchors and invalid middle offsets.

The initial native fixture captured its baseline before AppKit substituted the emoji fallback font. A focused diagnostic proved one notification but different system font attributes. The fixture now normalizes its baseline with fixAttributes before retaining it; strict full attribute restoration and all behavioral checks remain. Core and the app build were not repeated. The aligned coordinate fixture was then strengthened to use a short section between two conflicts; it proves the wrong serialized candidates cannot expose the desired source range. Only that folding case was rerun and passed, with no Core/build repeat. All eleven owned native receivers from the attempts were reaped and independently absent. See batch evidence.

The older hosted implementation passed its Git integration step, confirming the earlier About test compiler repair, and progressed into native checks. A full current implementation hosted pass and the earlier folding timeout root cause remain open. Physical input, exact visual comparison, large-document end-to-end performance and signed acceptance remain open.

Hosted Collapse stall diagnosis — October 17, 2026

The completed b818417d hosted run passed all 1,809 Core tests (two skipped) and the first ten wrapped-editor cases, then timed out at 300 seconds in folding. The retained stderr ends at pair loaded; collapsing, before the fixture reaches its TextKit measurement phase. Receiver 81749 was reaped. The same folding case passes locally, so the blocked code and a production repair remain unproven.

The wrapped family now opts into a two-second stack sample of its own live receiver after a timeout and before mandatory process-group cleanup. Sampling has a separate ten-second command bound; its failure preserves the original timeout. CI retains the stack file as a failure artifact. The family runs once immediately after the Debug app build, allowing this known failure to report before the full Core suite. No assertion, case or timeout was relaxed. See diagnostic evidence.

A current universal Debug build and the same full folding case under x86_64 Rosetta also pass locally (receiver 11027). This is not a macOS 15 Intel hardware reproduction. The nine receiver contracts pass; their initial ResourceWarnings exposed captured pipes retained through timeout tracebacks. Explicit pipe closure after reaping fixes that defect, and only those affected contracts were repeated. No timeout/assertion was relaxed and no production Collapse fix is claimed.

Complete native presentation transactions — October 17, 2026

Two-pane Compare and the three-pane Merge source/result renderers now commit font, per-row colors, inline emphasis and the final fold map in one NSTextStorage editing transaction. Restoring hidden attributes no longer publishes an intermediate unfolded paragraph map before reapplying source presentation. Synchronous aligned-result installation includes its initial fold restoration in the same transaction too. Caret translation, block centering and geometry measurement occur after that complete attributed snapshot commits. Selection notifications caused by installing the presentation cannot reveal a stale fold map or replace the pending model caret. User selection callbacks resume when installation ends; text, source coordinates and document Undo remain separate.

This repairs a concrete partial-style publication gap in the native port. It is not yet proof of the hosted wrapped-navigation/folding stall's cause. The local pre-change wrapped-navigation baseline passed, while the older macOS CI job timed out. The instrumented current run remains the authority for that gate.

Batch evidence records the grouped native scope and remaining physical/minimum-OS/signed acceptance.

The Debug build and all fifteen native cases passed at the grouped checkpoint: twelve wrapped/folding/navigation/ownership cases plus Unicode typing and the two-pane/three-pane editing engines. The new hosted-refresh observer checks saw six and eleven complete storage notifications respectively, with no intermediate fold map and unchanged text/carets. Every owned receiver, including the pre-change baseline, was reaped and independently absent. Core was unchanged and not rerun. This is local unsigned evidence; the active hosted run had not reached its editor gate at the final observation, so hosted resolution is not claimed.

Three-way result hide metadata — October 19, 2026

The three-way continuation replaces color-state folding predicates with the result's explicit hide flags. Common ignored conflicts can remain hidden as in the pinned source; Continue resolving conflicts reveals them without resolving their metadata. Source partners, copied block flags, aligned result rows and serialized fallback all use the same independent map. This supersedes earlier state-based three-pane folding descriptions. Evidence and physical/signed limits remain in the dated checkpoint.