Fix workspace diff multi-patch rendering

packages/plugins/plugin-workspace-diff/src/diff-model.ts

@@ -7,6 +7,17 @@ import type {
 
 export type DiffRenderMode = "unified" | "split";
 
+export interface DiffPatchViewModel {
+  kind: WorkspaceDiffFilePatch["kind"];
+  patch: string | null;
+  additions: number;
+  deletions: number;
+  binary: boolean;
+  oversized: boolean;
+  truncated: boolean;
+  warnings: WorkspaceDiffWarning[];
+}
+
 export interface DiffFileViewModel {
   path: string;
   oldPath: string | null;
@@ -18,6 +29,7 @@ export interface DiffFileViewModel {
   truncated: boolean;
   warnings: WorkspaceDiffWarning[];
   patchKinds: WorkspaceDiffFilePatch["kind"][];
+  patches: DiffPatchViewModel[];
   patch: string | null;
 }
 
@@ -47,17 +59,30 @@ export function fileName(filePath: string) {
   return filePath.split("/").filter(Boolean).pop() ?? filePath;
 }
 
+export function buildFilePatches(file: WorkspaceDiffFile): DiffPatchViewModel[] {
+  return file.patches.map((patch) => {
+    const textPatch = patch.patch?.trimEnd() ?? null;
+    return {
+      kind: patch.kind,
+      patch: textPatch && textPatch.length > 0 ? textPatch : null,
+      additions: patch.additions,
+      deletions: patch.deletions,
+      binary: patch.binary,
+      oversized: patch.oversized,
+      truncated: patch.truncated,
+      warnings: patch.warnings,
+    };
+  });
+}
+
 export function buildFilePatch(file: WorkspaceDiffFile): string | null {
-  const patches = file.patches
-    .map((patch) => patch.patch?.trimEnd() ?? "")
-    .filter(Boolean);
-  if (patches.length === 0) return null;
-  return patches.join("\n");
+  return buildFilePatches(file).find((patch) => patch.patch)?.patch ?? null;
 }
 
 export function toFileViewModels(diff: WorkspaceDiffResponse | null | undefined): DiffFileViewModel[] {
   return (diff?.files ?? []).map((file) => {
     const patchWarnings = file.patches.flatMap((patch) => patch.warnings);
+    const patches = buildFilePatches(file);
     return {
       path: file.path,
       oldPath: file.oldPath,
@@ -69,7 +94,8 @@ export function toFileViewModels(diff: WorkspaceDiffResponse | null | undefined)
       truncated: file.truncated,
       warnings: [...file.warnings, ...patchWarnings],
       patchKinds: file.patches.map((patch) => patch.kind),
-      patch: buildFilePatch(file),
+      patches,
+      patch: patches.find((patch) => patch.patch)?.patch ?? null,
     };
   });
 }

packages/plugins/plugin-workspace-diff/src/ui/index.tsx

@@ -10,6 +10,7 @@ import {
   statusLabel,
   toFileViewModels,
   type DiffFileViewModel,
+  type DiffPatchViewModel,
   type DiffRenderMode,
 } from "../diff-model.js";
 
@@ -38,7 +39,27 @@ function warningText(file: DiffFileViewModel) {
   if (file.oversized) return "Too large to render";
   if (file.truncated) return "Patch truncated";
   if (file.warnings.length > 0) return file.warnings[0]?.message ?? "Diff warning";
-  if (!file.patch) return "No text patch";
+  if (file.patches.every((patch) => !patch.patch)) return "No text patch";
+  return null;
+}
+
+const PATCH_KIND_LABELS: Record<DiffPatchViewModel["kind"], string> = {
+  staged: "Staged",
+  unstaged: "Unstaged",
+  head: "Head",
+  untracked: "Untracked",
+};
+
+function patchKindLabel(kind: DiffPatchViewModel["kind"]) {
+  return PATCH_KIND_LABELS[kind] ?? "Patch";
+}
+
+function patchWarningText(patch: DiffPatchViewModel) {
+  if (patch.binary) return "Binary file";
+  if (patch.oversized) return "Too large to render";
+  if (patch.truncated) return "Patch truncated";
+  if (patch.warnings.length > 0) return patch.warnings[0]?.message ?? "Diff warning";
+  if (!patch.patch) return "No text patch";
   return null;
 }
 
@@ -139,7 +160,7 @@ function FileDiffPanel({
   mode: DiffRenderMode;
 }) {
   const warning = warningText(file);
-  if (warning || !file.patch) {
+  if (warning) {
     return (
       <div className="border border-dashed border-border bg-background px-4 py-6 text-sm text-muted-foreground">
         {warning ?? "No renderable patch is available for this file."}
@@ -148,16 +169,36 @@ function FileDiffPanel({
   }
 
   return (
-    <div className="overflow-hidden border border-border bg-background">
-      <PatchDiff
-        patch={file.patch}
-        options={{
-          diffStyle: mode,
-          overflow: "scroll",
-          disableLineNumbers: false,
-          themeType: "system",
-        }}
-      />
+    <div className="space-y-3">
+      {file.patches.map((patch) => {
+        const patchWarning = patchWarningText(patch);
+        return (
+          <div key={patch.kind} className="overflow-hidden border border-border bg-background">
+            {file.patches.length > 1 ? (
+              <div className="flex items-center gap-2 border-b border-border bg-muted/30 px-3 py-2 text-xs text-muted-foreground">
+                <span className="font-medium text-foreground">{patchKindLabel(patch.kind)}</span>
+                <span className="font-mono text-emerald-700 dark:text-emerald-300">+{patch.additions}</span>
+                <span className="font-mono text-red-700 dark:text-red-300">-{patch.deletions}</span>
+              </div>
+            ) : null}
+            {patchWarning || !patch.patch ? (
+              <div className="px-4 py-6 text-sm text-muted-foreground">
+                {patchWarning ?? "No renderable patch is available for this file."}
+              </div>
+            ) : (
+              <PatchDiff
+                patch={patch.patch}
+                options={{
+                  diffStyle: mode,
+                  overflow: "scroll",
+                  disableLineNumbers: false,
+                  themeType: "system",
+                }}
+              />
+            )}
+          </div>
+        );
+      })}
     </div>
   );
 }

packages/plugins/plugin-workspace-diff/tests/diff-model.spec.ts

@@ -1,6 +1,7 @@
 import { describe, expect, it } from "vitest";
 import {
   buildFilePatch,
+  buildFilePatches,
   diffSummary,
   nextExpandedFileSet,
   statusLabel,
@@ -47,6 +48,64 @@ describe("workspace diff UI model", () => {
     });
   });
 
+  it("keeps staged and unstaged patches renderable as separate single-file diffs", () => {
+    const stagedPatch = [
+      "diff --git a/src/app.ts b/src/app.ts",
+      "index 1111111..2222222 100644",
+      "--- a/src/app.ts",
+      "+++ b/src/app.ts",
+      "@@ -1 +1 @@",
+      "-export const value = 1;",
+      "+export const value = 2;",
+      "",
+    ].join("\n");
+    const unstagedPatch = [
+      "diff --git a/src/app.ts b/src/app.ts",
+      "index 2222222..3333333 100644",
+      "--- a/src/app.ts",
+      "+++ b/src/app.ts",
+      "@@ -3 +3 @@",
+      "-export const label = 'old';",
+      "+export const label = 'new';",
+      "",
+    ].join("\n");
+    const file = changedFile({
+      staged: true,
+      unstaged: true,
+      patches: [
+        {
+          kind: "staged",
+          patch: stagedPatch,
+          additions: 1,
+          deletions: 1,
+          binary: false,
+          oversized: false,
+          truncated: false,
+          warnings: [],
+        },
+        {
+          kind: "unstaged",
+          patch: unstagedPatch,
+          additions: 1,
+          deletions: 1,
+          binary: false,
+          oversized: false,
+          truncated: false,
+          warnings: [],
+        },
+      ],
+    });
+
+    const patches = buildFilePatches(file);
+    const viewModel = toFileViewModels(diffResponse({ files: [file] }))[0];
+
+    expect(buildFilePatch(file)).toBe(stagedPatch.trimEnd());
+    expect(patches.map((patch) => patch.kind)).toEqual(["staged", "unstaged"]);
+    expect(patches.map((patch) => patch.patch?.match(/^diff --git/gm)?.length ?? 0)).toEqual([1, 1]);
+    expect(viewModel?.patches).toHaveLength(2);
+    expect(viewModel?.patchKinds).toEqual(["staged", "unstaged"]);
+  });
+
   it("toggles expanded file state without mutating the current set", () => {
     const current = new Set(["a.ts"]);
     const collapsed = nextExpandedFileSet(current, "a.ts");