fix: restore tab and diff context through jump history

docs/architecture.md

@@ -37,7 +37,7 @@ Frontends inspect `count()` for the optional pending numeric prefix; parsing, co
 Frontends inspect `sequence_pending()` for the cached display of a pending key sequence; prefix recognition, cancellation, and dispatch remain editor-owned. Symbolic leader routes and explicit key prefixes share the same binding storage and dispatcher; explicit prefixes do not change when the leader is reconfigured.
 Frontends inspect `g_pending()` for the built-in Normal/Visual `gt`/`gb` prefix and Normal-only `gf`. Document-edge motions share multi-target motion dispatch and viewport reveal, retaining Visual anchors and selection shape. Markdown following preflights links and headings before buffer/caret mutation; an unloaded target is validated/prepared once, while loaded targets use their current unsaved text. File identity and activation stay editor-owned.
 Frontends inspect `line_operator_pending()` for the optional Normal `d`/`c` prefix. Dedicated `dd`/`cc` actions project counted caret rows through existing linewise selection normalization, clipboard publication, and atomic range editing, without exposing a temporary Visual mode. Clipboard failures restore the original targets before returning. Repeat recipes retain the requested row count rather than the originally clamped range; change recipes share the existing Insert undo group. There is no general operator–motion parser.
-Editor-owned jump history is a bounded 100-location `VecDeque` of buffer IDs and grapheme cursors plus a current index, with no copied paths/text. Successful high-level navigation records departure/destination once; traversal uses unrecorded buffer activation and position placement, skips closed/clamped-duplicate locations, and truncates forward entries only on a distinct new jump. Session synchronization permanently invalidates pending LSP position requests after their source buffer/revision/caret/mode is left, so returning through history cannot revive an old definition reply.
+Editor-owned jump history is a bounded 100-location `VecDeque` of stable tab/pane identities, buffer IDs, grapheme cursors, and optional comparison identity/file/focus/binding metadata, with no copied paths/text. Successful high-level navigation records departure/destination once; traversal resolves a valid destination view before switching buffers, restores comparison binding and exact cursor visibility, and truncates forward entries only on a distinct new jump. Closed or replaced views fall back only to safe existing ordinary panes; history cannot resurrect a closed comparison or replace an unrelated one. Unavailable destinations are skipped without corrupting branch position. Session synchronization permanently invalidates pending LSP position requests after their source buffer/revision/caret/mode is left, so returning through history cannot revive an old definition reply.
 Frontends inspect `buffer_id()`, `buffer_count()`, `has_buffer(id)`, and the ascending-ID `buffers()` iterator of borrowed path/dirty/active metadata. Existing text, cursor, selection, search, and mode methods describe only the active buffer.
 Frontends inspect `tab_id()` for stable identity, `tab_index()` for display order, `tab_count()`, and `tab_buffer(index)` for borrowed title metadata. `pane_layout()` describes only the active tab; globally unique pane IDs keep inactive tabs' viewports alive. Documents remain unique across all tabs, while independent pane/buffer views are parked and restored without copying text.
 Frontends borrow `top_bar_config()` and `bottom_bar_config()` for validated ordered left/center/right segment groups and effective segment styles, and `label(name)` for session-wide custom values. The TUI owns terminal-cell widths, full-row center anchoring, clipping, and accent styling. Label effects carry only a name and plain text; they are global presentation updates, not buffer/revision-bound results or render callbacks.

docs/configuration.md

@@ -63,7 +63,7 @@ Vamp.configure do |config|
   config.bar.bottom = {
     left: [:tabs], center: [], right: [:battery],
     tabs: {
-      title: "{index} {name}{modified}", padding: 1,
+      title: "{index} {view}{name}{modified}", padding: 1,
       leading_edge: "░▒▓", trailing_edge: "▓▒░", first_leading_edge: ""
     },
     battery: { padding: 1, leading_edge: "░▒▓", trailing_edge: "" }
@@ -75,7 +75,7 @@ Builtins are `:tabs`, `:battery`, `:mode`, `:path`, `:position`, `:language`, `:
 
 A bar with no visible content consumes no row. For example, `config.bar.top = { left: [], center: [], right: [] }` removes the top bar. A bar whose only visible content is `:tabs` is hidden with a single tab, whether above or below the workspace. Narrow layouts first omit inactive tabs, then optional segments from group ends to avoid overlap; the active tab drops decorations before its title is clipped. Commands and buffer searches use floating input; operation feedback uses a bottom-right popup. Neither reserves a footer row.
 
-Each segment's `title` is a literal template supporting only `{index}`, `{name}`, `{path}`, and `{modified}`: the one-based tab index, filename, file path, and dirty marker (`" [+]"` when dirty, `""` when clean). Tabs use each tab's buffer metadata; other segments use the active buffer. Tabs default to `"{index} {name}{modified}"`; an empty title on another segment uses its builtin content or named label value. Templates are not Ruby code and never invoke a render callback.
+Each segment's `title` is a literal template supporting only `{index}`, `{view}`, `{name}`, `{path}`, and `{modified}`: the one-based tab index, comparison-view marker, filename, file path, and dirty marker (`" [+]"` when dirty, `""` when clean). `{view}` expands to `"Diff · "` when the tab owns a comparison or revision selector, otherwise `""`. Tabs use each tab's view and buffer metadata; other segments use the active context. Tabs default to `"{index} {view}{name}{modified}"`; custom templates without `{view}` retain their output. An empty title on another segment uses its builtin content or named label value. Templates are not Ruby code and never invoke a render callback.
 
 `:path` and `{path}` abbreviate the actual home-directory prefix to `~/` (`~` for the home directory itself). This is display-only: save paths, buffer identity, and LSP file URIs retain the original path. Sibling directories with similar names are not abbreviated.
 

docs/editing.md

@@ -359,11 +359,11 @@ Space begins a leader sequence in Normal/Visual by default. Explicit sequences s
 
 ## Jump history
 
-Normal Ctrl+o moves back through previous locations; Ctrl+i moves forward. Traditional terminals encode Ctrl+i as Tab, so Normal Tab performs the same action while Insert Tab inserts text outside snippets. Counts work in either direction, such as `3` followed by Ctrl+o, and stop at the available history.
+Normal Ctrl+o moves back through previous locations; Ctrl+i moves forward. Traditional terminals encode Ctrl+i as Tab, so Normal Tab performs the same action outside comparisons while Insert Tab inserts text outside snippets. In a comparison, Ctrl+i/Tab retains its diff-side focus behavior; use the **Jump forward** palette action or another configured key such as `config.bind "ctrl+y", config.core.jump_forward`. Counts work in either direction, such as `3` followed by Ctrl+o, and stop at the available history.
 
-The session keeps up to 100 primary-caret locations across buffers. Successful Markdown links, accepted LSP definitions, file-picker opens, `:edit`, `:buffer`, `:bnext`/`:bprev`, and search `/`/`n`/`N` jumps record locations. Ordinary cursor/word motion, edits, failed navigation, and jumps that do not change location do not add entries. Traversal itself does not record another jump.
+The session keeps up to 100 primary-caret locations with their tab, pane, and comparison context, not just buffer coordinates. Successful Markdown links, accepted LSP definitions, file-picker opens, `:edit`, `:buffer`, `:bnext`/`:bprev`, and search `/`/`n`/`N` jumps record locations. Back/forward restores the original view, including its comparison file and side; an external LSP definition round-trip does not replace the comparison with an ordinary buffer. Identical buffer/cursor positions in different views remain distinct. Ordinary cursor/word motion, edits, failed navigation, manual tab/pane selection, and jumps that do not change location do not add entries. Traversal itself does not record another jump.
 
-Moving away from a visited point before traversing saves the actual departure position for the return trip. A successful new jump after going back discards the forward branch; failed/no-op jumps preserve it. Closed buffers are skipped rather than reopened. Stored row/grapheme coordinates clamp to the current text after edits; text, dirty state, undo/redo, and file contents are unchanged by traversal. History navigation returns to Normal with one primary caret.
+Moving away from a visited point before traversing saves the actual departure position for the return trip. A successful new jump after going back discards the forward branch; failed/no-op jumps preserve it. Closed buffers are skipped rather than reopened. An unavailable or replaced comparison is never resurrected or overwritten: history uses a safe existing ordinary pane for an available buffer, retaining snapshot read-only identity, or skips the destination if none exists. It never creates a replacement tab. Stored row/grapheme coordinates clamp to current text after edits; text, dirty state, undo/redo, and file contents remain unchanged. History navigation returns to Normal with one primary caret.
 
 The typed actions are `config.core.jump_back` and `config.core.jump_forward`; custom bindings can use any supported single key or leader sequence. History is in memory for this session only.