fix(web): review comments keep a trailing blank line in their diff

apps/web/src/reviewCommentContext.test.ts

@@ -5,6 +5,7 @@ import { describe, expect, it } from "vite-plus/test";
 import {
   buildDiffReviewComment,
   buildFileReviewComment,
+  buildReviewCommentRenderablePatch,
   formatReviewCommentFence,
   resolveDiffReviewAnchor,
   resolveDiffReviewPosition,
@@ -75,6 +76,38 @@ describe("review comment context parsing", () => {
     );
   });
 
+  it("keeps a selection's trailing blank line and whitespace in the rendered excerpt", () => {
+    const fileDiff = parsePatchFiles(
+      [
+        "diff --git a/src/app.ts b/src/app.ts",
+        "--- a/src/app.ts",
+        "+++ b/src/app.ts",
+        "@@ -1,4 +1,4 @@",
+        " one",
+        "-two",
+        "+two\t",
+        " ",
+        " four",
+      ].join("\n"),
+      "review-comment-trailing-blank",
+    )[0]!.files[0]!;
+    const comment = (end: number) =>
+      buildDiffReviewComment({
+        id: "comment-blank",
+        sectionId: "turn:1",
+        sectionTitle: "Turn 1",
+        filePath: "src/app.ts",
+        fileDiff,
+        range: { start: 2, side: "additions", end, endSide: "additions" },
+        text: "Insert here.",
+      })!;
+
+    expect(buildReviewCommentRenderablePatch(comment(2))).toMatch(/\n\+two\t$/);
+    expect(buildReviewCommentRenderablePatch(comment(3))).toMatch(
+      /\n@@ -3,1 \+2,2 @@\n\+two\t\n $/,
+    );
+  });
+
   it("restores Pierre line selections from persisted diff comment row indexes", () => {
     const fileDiff = parsePatchFiles(
       [

apps/web/src/reviewCommentContext.ts

@@ -512,10 +512,10 @@ export function buildReviewCommentRenderablePatch(comment: ReviewCommentContext)
   if ((comment.fenceLanguage ?? "diff") !== "diff") {
     return "";
   }
-  const diff = comment.diff.trim();
-  if (diff.length === 0) {
+  if (comment.diff.trim().length === 0) {
     return "";
   }
+  const diff = comment.diff.trimStart().replace(/\n+$/, "");
   if (diff.startsWith("diff --git ")) {
     return diff;
   }

packages/shared/src/composerContextReferences.test.ts

@@ -221,6 +221,29 @@ describe("provider projection", () => {
     expect(project("a\n")).toContain("3 | a\n4 | \n</context>");
   });
 
+  it("keeps a review excerpt's trailing blank line and whitespace", () => {
+    const projected = projectComposerContextForProvider({
+      text: "[Comment](t3-context://v1/review-comment/ctx_r)",
+      records: [
+        {
+          version: 1,
+          contextId: ctx("ctx_r"),
+          kind: "review-comment",
+          label: "Comment",
+          sectionId: "turn:1",
+          sectionTitle: "Turn 1",
+          filePath: "src/app.ts",
+          startIndex: 1,
+          endIndex: 2,
+          rangeLabel: "2 to 3",
+          text: "Insert here.",
+          diff: "@@ -3,1 +2,2 @@\n+two\t\n \n",
+        },
+      ],
+    });
+    expect(projected).toContain("diff:\n  @@ -3,1 +2,2 @@\n  +two\t\n   \n</context>");
+  });
+
   it("emits no terminal lines when the captured range is inverted", () => {
     const projected = projectComposerContextForProvider({
       text: "[log](t3-context://v1/terminal/ctx_t)",

packages/shared/src/composerContextReferences.ts

@@ -289,7 +289,7 @@ function formatComposerContextProviderPayload(record: KnownComposerContextRecord
       ];
       if (record.text.trim()) lines.push("comment:", indent(record.text.trim()));
       if (record.diff.trim()) {
-        lines.push(`${record.fenceLanguage ?? "diff"}:`, indent(record.diff.trimEnd()));
+        lines.push(`${record.fenceLanguage ?? "diff"}:`, indent(record.diff.replace(/\n+$/, "")));
       }
       return lines.join("\n");
     }