Code tab: right-click Open path:N jumps to file at that line (#891)

**The Code tab's right-click menu gains an `Open <path>:<line>` entry.**
Reviewing a diff and wanting the full file at the same line was
previously two steps — copy `path:N`, switch to browse mode,
paste-navigate. Now it's one click; the menu item dispatches through the
same pipeline a terminal-link click does.

This is **Phase 0 of #881's redo** — small user-visible win on top of a
seam Phase 1 (line-anchored comments) will reuse. The structural review
behind the redo is in #881's body and replaces #879.

### Before / after

```
Diff view: alpha
           beta            ← right-click line 2
           gamma

Before:    [Copy path]    [Copy notes.txt:2]
After:     [Copy path]    [Copy notes.txt:2]    [Open notes.txt:2]
                                                 └──┐
                                          one click ▼
                                          browse mode, file open, line 2 highlighted
```

### The seam

The terminal-link click pipeline used to require a **paired write** at
every call site:

```ts
// Terminal.tsx (before)
rightPanel.openCodeBrowser();   // ① uncollapse + tab + browse-mode
requestCodeOpen({ ref, repoRoot, cwd, targetMode: "browse" });  // ② pending
// Comment: "must fire in the same DOM-event tick or resetKey clears
//  what pendingCodeOpen is about to set."
```

The ordering hazard sat at the call site as documented discipline, which
meant every new producer (right-click _Open_, future _Comment on_)
inherited the same wall-of-text rationale. Phase 0 collapses both writes
into one function:

```ts
// Terminal.tsx (after)
openInCodeTab({ ref, repoRoot, cwd, targetMode: "browse" });
```

`openInCodeTab` (replacing `codeNavigation.ts`) encapsulates both
writes; `useRightPanel.openCodeBrowser()` is generalized to
`openCodeAt(mode: CodeTabView)` so a Phase 1 comment authored while
reviewing a diff can re-open in that diff mode rather than always
browse.

### What landed

| Layer | Change |
| --- | --- |
| Producer-facing | `openInCodeTab(req)` — single call replaces the
paired-write pattern at every site |
| Panel state | `useRightPanel.openCodeAt(mode)` — atomic three-field
preferences patch parameterized on the target sub-mode; skips the patch
when already at target |
| Menu data | `CodeContextMenuItem` becomes a discriminated union
(`kind: "copy"` vs `kind: "action"`); `handleItem` dispatches via
`ts-pattern.exhaustive()` |
| Selection hook | `useLineSelection` gains `onOpen?: Accessor<((ref) =>
void) \| undefined>`; when present and a range is selected, an _Open
path:N_ action item is emitted |
| Code tab wiring | The diff-view `CodeMenuFrame` passes `onOpen` that
routes through `openInCodeTab`. The browse-view path deliberately omits
it — the file is already on screen at line precision |

_The `Accessor<…>` shape on `onOpen` mirrors `initialRange` — buildItems
runs at menu-open time, so a host whose prop arrives late in the SolidJS
lifecycle still flips the item in._

### Test coverage

- `code-tab.feature` — new scenario: right-click in diff view, click
_Open notes.txt:2_, assert mode flipped to browse + file selected + line
2 highlighted
- `code-tab.feature` — updated multi-file diff scenario to assert the
three-item menu (`Copy path | Copy file-b.txt:1 | Open file-b.txt:1`)
- `file-ref-link.feature` — terminal-link clicks now flow through
`openInCodeTab`; all three pre-existing scenarios still pass

43/43 scenarios, 503/503 steps locally.

### Try it locally

```sh
nix run github:juspay/kolu/open-in-code-tab
```

_Generated by [`/do`](https://github.com/srid/agency) on Claude Code
(model `claude-opus-4-7`)._

Author: srid

packages/client/src/right-panel/CodeMenuFrame.tsx

@@ -11,6 +11,7 @@ import {
   CodeContextMenu,
   type CodeContextMenuController,
 } from "../ui/CodeContextMenu";
+import type { LineRef } from "../ui/lineRef";
 import { type LineSelection, useLineSelection } from "../ui/useLineSelection";
 
 export type CodeMenuFrameProps = {
@@ -25,19 +26,57 @@ export type CodeMenuFrameProps = {
    *  controller so a terminal `path:line` click drives both the
    *  Pierre highlight AND the right-click menu's "Copy path:N" item. */
   initialSelectedLines?: SelectedLineRange | null;
+  /** When provided, adds an "Open <path>:<line>" entry to the context
+   *  menu that dispatches the selected ref to the host (typically a
+   *  call to `openInCodeTab`). Omit for viewers where "open" is a
+   *  no-op (the file is already on screen at line precision). */
+  onOpen?: (ref: LineRef) => void;
 };
 
+/** Walk the contextmenu event's composed path (which pierces Pierre's
+ *  open shadow DOM, where `event.target` would otherwise be retargeted
+ *  to the shadow host) and return the line number from the first
+ *  element carrying `data-column-number`. Returns null when the
+ *  right-click landed outside any gutter line — empty area, scrollbar,
+ *  decoration row — so the host can skip opening a menu entirely. */
+function lineFromContextMenu(event: MouseEvent): number | null {
+  for (const node of event.composedPath()) {
+    if (!(node instanceof Element)) continue;
+    const raw = node.getAttribute("data-column-number");
+    if (raw === null) continue;
+    const n = Number(raw);
+    if (Number.isFinite(n) && n >= 1) return n;
+  }
+  return null;
+}
+
 export const CodeMenuFrame: Component<CodeMenuFrameProps> = (props) => {
   let menuCtrl: CodeContextMenuController | undefined;
   const selection = useLineSelection(() => props.path, {
     initialRange: () => props.initialSelectedLines,
+    onOpen: () => props.onOpen,
   });
   return (
     <div
       // Attach contextmenu via addEventListener so the host div doesn't
       // carry interactive JSX props — the inner Pierre canvas is the
       // actual interactive surface; the host is layout only.
-      ref={(el) => el.addEventListener("contextmenu", (e) => menuCtrl?.open(e))}
+      ref={(el) =>
+        el.addEventListener("contextmenu", (e) => {
+          // Right-click on a gutter line is the single entry point for
+          // the context menu: it both selects the line and opens the
+          // menu in one gesture. Right-clicks elsewhere (whitespace,
+          // scrollbar, decoration row) clear the range and produce no
+          // menu — `buildItems` returns empty when no range is set,
+          // so `menuCtrl.open` short-circuits without preventing the
+          // browser default.
+          const line = lineFromContextMenu(e);
+          selection.handleSelect(
+            line === null ? null : { start: line, end: line },
+          );
+          menuCtrl?.open(e);
+        })
+      }
       class="h-full w-full"
     >
       {props.children(selection)}

packages/client/src/right-panel/CodeTab.tsx

@@ -41,8 +41,12 @@ import {
 } from "../ui/pierreTheme";
 import { resolveLineRefPath } from "../ui/lineRef";
 import BrowseFileView from "./BrowseFileView";
-import { type CodeOpenRequest, pendingCodeOpen } from "./codeNavigation";
 import CodeMenuFrame from "./CodeMenuFrame";
+import {
+  openInCodeTab,
+  type OpenInCodeTabRequest,
+  pendingOpen,
+} from "./openInCodeTab";
 import { projectFileTreeSearch } from "./fileSearch";
 import FileSearchInput from "./FileSearchInput";
 import ModeChipPicker, { type ModeOption } from "./ModeChipPicker";
@@ -176,57 +180,66 @@ const CodeTab: Component<{ meta: TerminalMetadata | null }> = (props) => {
   // absolute path or `null`, never the empty string that would alias
   // null.
   const resetKey = createMemo(() => `${repoPath() ?? ""}::${view()}`);
+
+  /** The resetKey effect runs BEFORE the pendingOpen effect by
+   *  registration order. When a navigation request is about to land in
+   *  the new (repo, mode) — same repoRoot, target mode equals the
+   *  freshly-ticked `view()`, and the request hasn't already been
+   *  consumed by `handled()` — the resetKey effect must skip its clear,
+   *  or the pendingOpen effect would null what we're about to set.
+   *  This predicate names the cross-effect temporal coupling so the
+   *  guard isn't a wall of inline conjunctions a future editor has to
+   *  re-derive. The `batch()` in `openInCodeTab` ensures both writes
+   *  (`view` and `pendingOpen`) commit before either effect fires; the
+   *  registration-order discipline survives ABOVE that. */
+  const isPendingOpenAboutToLand = (): boolean => {
+    const req = pendingOpen();
+    return (
+      req !== null &&
+      req.repoRoot === repoPath() &&
+      req.targetMode === view() &&
+      handled()?.request !== req
+    );
+  };
+
   createEffect(
     on(
       resetKey,
       () => {
         setSearchQuery("");
-        // Skip the selectedPath clear when an incoming request is
-        // about to land in the new mode — the resetKey effect runs
-        // before the pendingCodeOpen effect (registration order), and
-        // an unconditional clear would null what we're about to set.
-        // Reading `req.targetMode` (not `view()`) makes the guard
-        // robust to user-driven mode flips that race the click.
-        const req = pendingCodeOpen();
-        if (
-          req &&
-          req.repoRoot === repoPath() &&
-          req.targetMode === view() &&
-          handled()?.request !== req
-        ) {
-          return;
-        }
+        if (isPendingOpenAboutToLand()) return;
         setSelectedPath(null);
       },
       { defer: true },
     ),
   );
 
-  // Consume-once record for the latest pendingCodeOpen tick. Holds
-  // the full request object (reference identity discriminates two
-  // structurally-identical clicks — `requestCodeOpen` mints a fresh
+  // Consume-once record for the latest pendingOpen tick. Holds the
+  // full request object (reference identity discriminates two
+  // structurally-identical clicks — `openInCodeTab` mints a fresh
   // object per call) alongside the resolved path. Storing the
   // request here lets `selectedRange` derive its value without
   // re-running `resolveLineRefPath` (single resolution site per
   // request) and lets `resetKey` know whether a pending request
   // has already been applied.
   const [handled, setHandled] = createSignal<{
-    request: CodeOpenRequest;
+    request: OpenInCodeTabRequest;
     resolvedPath: string | null;
   } | null>(null);
 
-  // Honor terminal file-ref clicks. The effect waits for the live
-  // `fsListAll` stream to settle so resolution can validate against
-  // a complete file list — otherwise a request fired during boot
-  // would toast "not found" on a path that just hasn't been
-  // enumerated yet. The terminal click handler is the sole site that
-  // flips the panel to browse mode; this effect only sets
+  // Honor every `openInCodeTab` request — terminal file-ref clicks,
+  // right-click "Open path:N" entries, and any future producer. The
+  // effect waits for the live `fsListAll` stream to settle so
+  // resolution can validate against a complete file list — otherwise
+  // a request fired during boot would toast "not found" on a path
+  // that just hasn't been enumerated yet. `openInCodeTab` flips the
+  // panel to browse mode itself; this effect only sets
   // `selectedPath`. The `resetKey` effect above guards against
   // clearing selectedPath when this effect is about to set it.
   createEffect(
     on(
       () => {
-        const req = pendingCodeOpen();
+        const req = pendingOpen();
         const paths = treePaths();
         const isPending = allPaths.pending();
         return { req, repo: repoPath(), paths, isPending };
@@ -263,7 +276,7 @@ const CodeTab: Component<{ meta: TerminalMetadata | null }> = (props) => {
   //
   // No `equals` override: two clicks on the same `path:line` produce
   // structurally identical `{start, end}` but distinct request
-  // objects (`requestCodeOpen` mints a fresh one per call), so the
+  // objects (`openInCodeTab` mints a fresh one per call), so the
   // memo emits a fresh value on every click. Pierre's
   // `InteractionManager.setSelection` re-renders when the selection
   // is "dirty" — and tearing down the gutter (panel collapse,
@@ -275,7 +288,7 @@ const CodeTab: Component<{ meta: TerminalMetadata | null }> = (props) => {
     start: number;
     end: number;
   } | null>(() => {
-    const req = pendingCodeOpen();
+    const req = pendingOpen();
     if (!req) return null;
     const h = handled();
     if (!h || h.request !== req || h.resolvedPath === null) return null;
@@ -538,7 +551,19 @@ const CodeTab: Component<{ meta: TerminalMetadata | null }> = (props) => {
                     </Match>
                     <Match when={diff()}>
                       {(d) => (
-                        <CodeMenuFrame path={path}>
+                        <CodeMenuFrame
+                          path={path}
+                          onOpen={(ref) => {
+                            // Diff paths are repo-relative; cwd is irrelevant.
+                            const repo = repoPath();
+                            if (repo === null) return;
+                            openInCodeTab({
+                              ref,
+                              repoRoot: repo,
+                              targetMode: "browse",
+                            });
+                          }}
+                        >
                           {(selection) => (
                             // `<Virtualizer>` is the scroll container —
                             // `<FileDiff>` consumes its context and

packages/client/src/right-panel/codeNavigation.ts

@@ -13,6 +13,8 @@
  *  the directories the wrapper should ensure are open so matches don't
  *  hide behind a collapsed parent on first paint. */
 
+import { ancestorDirectoryPaths } from "@kolu/solid-pierre";
+
 type FileTreeSearchProjection = {
   projectedPaths: string[];
   expandedAncestors: string[];
@@ -39,21 +41,6 @@ function pathContainsTokensInOrder(
   return true;
 }
 
-/** Pierre uses `getAncestorDirectoryPaths` internally to drive
- *  expansion in `hide-non-matches` mode. Mirror that exact shape so
- *  the wrapper's expansion request reaches every dir Pierre infers
- *  from the projected paths. */
-function ancestorDirectoryPaths(path: string): string[] {
-  const normalized = path.endsWith("/") ? path.slice(0, -1) : path;
-  if (normalized.length === 0) return [];
-  const segments = normalized.split("/");
-  const out: string[] = [];
-  for (let i = 1; i < segments.length; i += 1) {
-    out.push(`${segments.slice(0, i).join("/")}/`);
-  }
-  return out;
-}
-
 export function projectFileTreeSearch(
   paths: string[],
   query: string,

packages/client/src/right-panel/fileSearch.ts

@@ -0,0 +1,59 @@
+/** Front door for "open this file:line in the Code tab". Every producer
+ *  — terminal-link click, right-click "Open path:N" context-menu entry,
+ *  future surfaces — calls `openInCodeTab(...)` instead of writing the
+ *  preferences patch and pending-request signal separately. The function
+ *  encapsulates the paired writes (panel-uncollapse + tab + browse-mode +
+ *  pending request) so the SolidJS effect-ordering invariant lives here,
+ *  not at every call site.
+ *
+ *  Latest request wins; callers don't clear it. Each call mints a fresh
+ *  request object — two clicks on the same `path:line` are distinct by
+ *  reference, which is what lets `CodeTab` tell them apart even when
+ *  their `ref` content matches and re-paint the highlight. */
+
+import type { CodeTabView } from "kolu-common/surface";
+import { batch, createSignal } from "solid-js";
+import type { LineRef } from "../ui/lineRef";
+import { useRightPanel } from "./useRightPanel";
+
+export interface OpenInCodeTabRequest {
+  /** Parsed `path:line[-end]` to navigate to. The path is interpreted
+   *  relative to `repoRoot` (or, when present, cwd-relative under
+   *  `repoRoot`) by `CodeTab` via `resolveLineRefPath`. */
+  ref: LineRef;
+  /** Per-terminal git repo root that `ref.path` is relative to (when
+   *  relative). Absolute paths beneath this root are also accepted —
+   *  the resolver normalizes both shapes. */
+  repoRoot: string;
+  /** Terminal cwd at the time of the request. Drives the "user typed
+   *  `bar.ts:42` while standing in a subdirectory of the repo" case;
+   *  undefined falls back to repo-relative interpretation only. */
+  cwd?: string;
+  /** Which Code-tab sub-mode the request expects to land in.
+   *  Producers that don't track an authoring mode pass `"browse"`. */
+  targetMode: CodeTabView;
+}
+
+// Module-level singleton. Right-panel state is a singleton in Kolu —
+// one panel, one CodeTab — and the navigation request is meant for
+// the unique consumer. If kolu ever mounts multiple CodeTab instances
+// (split panels, multi-window), this signal must move into a
+// SolidJS context or scope to a per-panel store, otherwise concurrent
+// consumers will race on each other's pending requests.
+const [pending, setPending] = createSignal<OpenInCodeTabRequest | null>(null);
+
+export const pendingOpen = pending;
+
+/** Open the right panel's Code tab at `req.targetMode` showing `req.ref`.
+ *  The two reactive writes (preferences patch + pending-request signal)
+ *  are wrapped in `batch()` so SolidJS defers dependent effects until
+ *  both have committed. Without the batch, the preferences optimistic
+ *  update ticks `view()` first, fires `CodeTab`'s `resetKey` effect
+ *  when `pendingOpen()` is still null, the guard fails, and the
+ *  selectedPath the user navigated to gets cleared. */
+export function openInCodeTab(req: OpenInCodeTabRequest): void {
+  batch(() => {
+    useRightPanel().openCodeAt(req.targetMode);
+    setPending(req);
+  });
+}

packages/client/src/right-panel/openInCodeTab.ts

@@ -42,18 +42,26 @@ export function useRightPanel() {
           ...(mode !== undefined && { codeMode: mode }),
         },
       }),
-    /** Atomic "open the code browser at this file" — uncollapse the
-     *  panel, switch to Code, force browse mode. Single patch so the
-     *  UI ticks once instead of three times when callers need all
-     *  three transitions together. */
-    openCodeBrowser: () =>
+    /** Atomic "open the Code tab at `mode`" — uncollapse the panel,
+     *  switch to Code, set the requested sub-mode. Single preferences
+     *  patch so the UI ticks once instead of three times when callers
+     *  need all three transitions together. Skips the patch when the
+     *  panel is already in the target state (every diff→browse and
+     *  browse→browse `openInCodeTab` would otherwise round-trip a
+     *  three-field preferences write to the server). */
+    openCodeAt: (mode: CodeTabView) => {
+      const cur = rp();
+      if (!cur.collapsed && cur.activeTab === "code" && cur.codeMode === mode) {
+        return;
+      }
       updatePreferences({
         rightPanel: {
           collapsed: false,
           activeTab: "code",
-          codeMode: "browse",
+          codeMode: mode,
         },
-      }),
+      });
+    },
     /** Change the sub-mode within the Code tab. */
     setCodeMode: (mode: CodeTabView) =>
       updatePreferences({ rightPanel: { codeMode: mode } }),