Restrict TSX rendering source placement

biome.jsonc

@@ -9,11 +9,20 @@
     // App-server protocol and generated binding boundaries.
     {
       "path": "./scripts/lint/no-app-server-projection-rpcs.grit",
-      "includes": ["**/src/features/chat/application/**/*.ts", "**/src/features/chat/application/**/*.tsx"]
+      "includes": ["**/src/features/chat/application/**/*.ts"]
     },
     {
       "path": "./scripts/lint/no-app-server-protocol-boundary-imports.grit",
-      "includes": ["**/src/**/*.ts", "**/src/**/*.tsx", "!**/src/app-server/**/*.ts", "!**/src/app-server/**/*.tsx"]
+      "includes": [
+        "**/src/**/*.ts",
+        "!**/src/app-server/**/*.ts",
+        "**/src/features/chat/panel/**/*.tsx",
+        "**/src/features/chat/ui/**/*.tsx",
+        "**/src/features/selection-rewrite/**/*.tsx",
+        "**/src/features/threads-view/**/*.tsx",
+        "**/src/settings/**/*.tsx",
+        "**/src/shared/ui/**/*.tsx"
+      ]
     },
     {
       "path": "./scripts/lint/no-generated-app-server-boundary-imports.grit",
@@ -28,27 +37,15 @@
     // Shared source layering boundaries.
     {
       "path": "./scripts/lint/no-domain-outer-layer-imports.grit",
-      "includes": [
-        "**/src/domain/**/*.ts",
-        "**/src/domain/**/*.tsx",
-        "**/src/features/chat/domain/**/*.ts",
-        "**/src/features/chat/domain/**/*.tsx"
-      ]
+      "includes": ["**/src/domain/**/*.ts", "**/src/features/chat/domain/**/*.ts"]
     },
     {
       "path": "./scripts/lint/no-lower-level-feature-imports.grit",
-      "includes": ["**/src/app-server/**/*.ts", "**/src/app-server/**/*.tsx", "**/src/shared/**/*.ts", "**/src/shared/**/*.tsx"]
+      "includes": ["**/src/app-server/**/*.ts", "**/src/shared/**/*.ts", "**/src/shared/**/*.tsx"]
     },
     {
       "path": "./scripts/lint/no-app-server-connection-boundary-imports.grit",
-      "includes": [
-        "**/src/app-server/protocol/**/*.ts",
-        "**/src/app-server/protocol/**/*.tsx",
-        "**/src/domain/**/*.ts",
-        "**/src/domain/**/*.tsx",
-        "**/src/shared/**/*.ts",
-        "**/src/shared/**/*.tsx"
-      ]
+      "includes": ["**/src/app-server/protocol/**/*.ts", "**/src/domain/**/*.ts", "**/src/shared/**/*.ts", "**/src/shared/**/*.tsx"]
     },
 
     // Chat feature architecture.
@@ -58,7 +55,7 @@
     },
     {
       "path": "./scripts/lint/no-pure-chat-state-side-effects.grit",
-      "includes": ["**/src/features/chat/application/state/**/*.ts", "**/src/features/chat/application/state/**/*.tsx"]
+      "includes": ["**/src/features/chat/application/state/**/*.ts"]
     },
 
     // UI and DOM source boundaries.
@@ -76,6 +73,18 @@
     },
 
     // Project-wide source shape.
+    {
+      "path": "./scripts/lint/no-misplaced-tsx.grit",
+      "includes": [
+        "**/src/**/*.tsx",
+        "!**/src/features/chat/panel/**",
+        "!**/src/features/chat/ui/**",
+        "!**/src/features/selection-rewrite/**",
+        "!**/src/features/threads-view/**",
+        "!**/src/settings/**",
+        "!**/src/shared/ui/**"
+      ]
+    },
     {
       "path": "./scripts/lint/no-handwritten-reexports.grit",
       "includes": ["**/*.ts", "**/*.tsx", "**/*.mjs"]

docs/development.md

@@ -63,6 +63,8 @@ Chat panel-visible state belongs in `ChatStateStore` and should flow through nam
 
 Use imperative DOM writes only for explicit bridge modules, Obsidian-owned API boundaries, or rendering and measurement code that cannot be expressed cleanly as Preact components. Name those files with a `.dom`, `.obsidian`, or `.measure` suffix so Biome can enforce the boundary without file-specific allowlists.
 
+Use `.tsx` only in rendering-owned source folders: chat panel and UI modules, Obsidian/settings surfaces, selection rewrite and threads view renderers, and shared UI components. Non-rendering source should use `.ts`; Biome enforces this so lower-level app-server, domain, application, presentation, workspace, and generic shared modules do not grow JSX dependencies.
+
 ## CSS Rules
 
 CSS should stay native to Obsidian. Prefer Obsidian variables and Codex Panel tokens for color, typography, spacing, and layout dimensions instead of hardcoded values.

scripts/lint/no-misplaced-tsx.grit

@@ -0,0 +1,5 @@
+language js
+
+`$program` where {
+  register_diagnostic(span=$program, message="Keep TSX files in UI, panel, settings, or explicit render bridge modules; non-rendering source should use .ts.", severity="error")
+}

src/features/chat/ui/message-stream/detail.tsx

@@ -1,6 +1,6 @@
 import type { ComponentChild as UiNode } from "preact";
 
-import { RawDiffLines } from "../../../../shared/diff/render";
+import { RawDiffView } from "../../../../shared/ui/diff";
 import type { DetailSection, DetailView } from "../../presentation/message-stream/detail-view";
 import type { MessageStreamDisclosureState } from "./context";
 
@@ -84,7 +84,7 @@ function DetailSectionView({ section }: { section: DetailSection }): UiNode {
   if (section.kind === "diff") {
     return (
       <OutputSection title={section.title} className="codex-panel-diff-file">
-        <DiffLines diff={section.diff} />
+        <RawDiffView diff={section.diff} />
       </OutputSection>
     );
   }
@@ -139,7 +139,3 @@ function OutputSection({ title, className, children }: { title: string; classNam
     </div>
   );
 }
-
-function DiffLines({ diff }: { diff: string }): UiNode {
-  return <RawDiffLines diff={diff} />;
-}

src/features/chat/ui/turn-diff/render.dom.tsx

@@ -1,9 +1,8 @@
 import type { ComponentChild as UiNode } from "preact";
 
-import { DisplayDiffLines } from "../../../../shared/diff/render";
-import { displayDiffLines } from "../../../../shared/diff/unified";
 import { shortThreadId } from "../../../../shared/id/thread-id";
 import { IconButton } from "../../../../shared/ui/components.obsidian";
+import { UnifiedDiffView } from "../../../../shared/ui/diff";
 import { renderUiRoot } from "../../../../shared/ui/ui-root.dom";
 import type { ChatTurnDiffViewState, PersistedChatTurnDiffViewState } from "../../domain/turn-diff";
 
@@ -46,7 +45,7 @@ function ChatTurnDiffView({
     <>
       <TurnDiffHeader state={state} copyDiff={actions.copyDiff ?? null} />
       {state.files.length > 0 ? <ChangedFiles files={state.files} /> : null}
-      <UnifiedDiff diff={state.diff} />
+      <UnifiedDiffView diff={state.diff} className="codex-panel-chat-turn-diff__diff" />
     </>
   );
 }
@@ -86,10 +85,6 @@ function ChangedFiles({ files }: { files: string[] }): UiNode {
   );
 }
 
-function UnifiedDiff({ diff }: { diff: string }): UiNode {
-  return <DisplayDiffLines lines={displayDiffLines(diff)} className="codex-panel-chat-turn-diff__diff" />;
-}
-
 function fileCountLabel(files: string[]): string {
   return files.length === 1 ? "Edited 1 file" : `Edited ${String(files.length)} files`;
 }

src/features/selection-rewrite/popover.dom.tsx

@@ -1,9 +1,8 @@
 import { type Editor, Notice } from "obsidian";
 import type { TargetedKeyboardEvent, ComponentChild as UiNode } from "preact";
 
-import { DisplayDiffLines } from "../../shared/diff/render";
-import { displayDiffLines } from "../../shared/diff/unified";
 import { IconButton } from "../../shared/ui/components.obsidian";
+import { DiffLineList, unifiedDiffDisplayLines } from "../../shared/ui/diff";
 import { isComposerSendKey, type SendShortcut } from "../../shared/ui/keyboard";
 import { syncTextareaHeight } from "../../shared/ui/textarea-autogrow.measure";
 import { type TextareaCaretBoundaryDirection, textareaCursorAtVisualBoundary } from "../../shared/ui/textarea-caret.measure";
@@ -415,8 +414,8 @@ function SelectionRewriteStatus({ status }: { status: SelectionRewriteSessionSta
 
 function SelectionRewriteDiff({ diff }: { diff: string }): UiNode {
   return (
-    <DisplayDiffLines
-      lines={displayDiffLines(diff).filter((line) => line.kind !== "file" && !line.text.startsWith("@@"))}
+    <DiffLineList
+      lines={unifiedDiffDisplayLines(diff).filter((line) => line.kind !== "file" && !line.text.startsWith("@@"))}
       className="codex-panel-selection-rewrite__diff-body"
     />
   );

src/shared/diff/unified.ts

@@ -1,46 +0,0 @@
-export interface DisplayDiffLine {
-  text: string;
-  kind?: "file";
-}
-
-export type DiffLineClass = "added" | "removed" | "hunk" | "context" | "file";
-
-export function displayDiffLines(diff: string): DisplayDiffLine[] {
-  const displayLines: DisplayDiffLine[] = [];
-  let inFileHeader = false;
-  for (const line of diff.split("\n")) {
-    const file = filePathFromGitDiffHeader(line);
-    if (file) {
-      displayLines.push({ text: file, kind: "file" });
-      inFileHeader = true;
-      continue;
-    }
-    if (line.startsWith("@@")) inFileHeader = false;
-    if (inFileHeader && (line.startsWith("index ") || line.startsWith("--- ") || line.startsWith("+++ "))) continue;
-    displayLines.push({ text: line });
-  }
-  return displayLines;
-}
-
-export function diffLineClass(line: DisplayDiffLine): DiffLineClass {
-  if (line.kind === "file") return "file";
-  return diffLineClassFromText(line.text);
-}
-
-export function diffLineClassFromText(text: string): Exclude<DiffLineClass, "file"> {
-  if (text.startsWith("+") && !text.startsWith("+++")) return "added";
-  if (text.startsWith("-") && !text.startsWith("---")) return "removed";
-  if (text.startsWith("@@")) return "hunk";
-  return "context";
-}
-
-export function displayDiffLineText(text: string, lineClass: DiffLineClass): string {
-  const displayText = lineClass === "added" || lineClass === "removed" ? text.slice(1) : text;
-  return displayText || " ";
-}
-
-function filePathFromGitDiffHeader(line: string): string | null {
-  const match = /^diff --git a\/(.+) b\/(.+)$/.exec(line);
-  if (!match) return null;
-  return match[2] ?? null;
-}

src/shared/ui/diff.tsx

@@ -1,10 +1,15 @@
 import type { ComponentChild as UiNode } from "preact";
 
-import { type DiffLineClass, type DisplayDiffLine, diffLineClass, diffLineClassFromText, displayDiffLineText } from "./unified";
-
 const MAX_INLINE_DIFF_CHARS = 4000;
 const MAX_INLINE_DIFF_TOKENS = 500;
 
+export interface DiffDisplayLine {
+  text: string;
+  kind?: "file";
+}
+
+type DiffLineClass = "added" | "removed" | "hunk" | "context" | "file";
+
 interface InlineDiffPart {
   text: string;
   changed: boolean;
@@ -26,17 +31,61 @@ interface DiffLineView extends RenderDiffLine {
 
 type ChangeLineClass = "added" | "removed";
 
-export function DisplayDiffLines({ lines, className }: { lines: readonly DisplayDiffLine[]; className?: string | undefined }): UiNode {
-  return <DiffLines lines={lines.map((line) => ({ text: line.text, className: diffLineClass(line) }))} className={className} />;
+export function unifiedDiffDisplayLines(diff: string): DiffDisplayLine[] {
+  const displayLines: DiffDisplayLine[] = [];
+  let inFileHeader = false;
+  for (const line of diff.split("\n")) {
+    const file = filePathFromGitDiffHeader(line);
+    if (file) {
+      displayLines.push({ text: file, kind: "file" });
+      inFileHeader = true;
+      continue;
+    }
+    if (line.startsWith("@@")) inFileHeader = false;
+    if (inFileHeader && (line.startsWith("index ") || line.startsWith("--- ") || line.startsWith("+++ "))) continue;
+    displayLines.push({ text: line });
+  }
+  return displayLines;
 }
 
-export function RawDiffLines({ diff, className }: { diff: string; className?: string | undefined }): UiNode {
+export function UnifiedDiffView({ diff, className }: { diff: string; className?: string | undefined }): UiNode {
+  return <DiffLineList lines={unifiedDiffDisplayLines(diff)} className={className} />;
+}
+
+export function DiffLineList({ lines, className }: { lines: readonly DiffDisplayLine[]; className?: string | undefined }): UiNode {
+  return <DiffLineFrame lines={lines.map((line) => ({ text: line.text, className: diffLineClass(line) }))} className={className} />;
+}
+
+export function RawDiffView({ diff, className }: { diff: string; className?: string | undefined }): UiNode {
   return (
-    <DiffLines lines={diff.split("\n").map((line) => ({ text: line, className: diffLineClassFromText(line) }))} className={className} />
+    <DiffLineFrame lines={diff.split("\n").map((line) => ({ text: line, className: diffLineClassFromText(line) }))} className={className} />
   );
 }
 
-function DiffLines({ lines, className }: { lines: readonly RenderDiffLine[]; className?: string | undefined }): UiNode {
+function diffLineClass(line: DiffDisplayLine): DiffLineClass {
+  if (line.kind === "file") return "file";
+  return diffLineClassFromText(line.text);
+}
+
+function diffLineClassFromText(text: string): Exclude<DiffLineClass, "file"> {
+  if (text.startsWith("+") && !text.startsWith("+++")) return "added";
+  if (text.startsWith("-") && !text.startsWith("---")) return "removed";
+  if (text.startsWith("@@")) return "hunk";
+  return "context";
+}
+
+function displayDiffLineText(text: string, lineClass: DiffLineClass): string {
+  const displayText = lineClass === "added" || lineClass === "removed" ? text.slice(1) : text;
+  return displayText || " ";
+}
+
+function filePathFromGitDiffHeader(line: string): string | null {
+  const match = /^diff --git a\/(.+) b\/(.+)$/.exec(line);
+  if (!match) return null;
+  return match[2] ?? null;
+}
+
+function DiffLineFrame({ lines, className }: { lines: readonly RenderDiffLine[]; className?: string | undefined }): UiNode {
   const preClassName = ["codex-panel-diff", className].filter(Boolean).join(" ");
   return (
     <pre className={preClassName}>

tests/scripts/grit-policy.test.mjs

@@ -393,6 +393,61 @@ export type Params = ToolRequestUserInputParams;
     expect(pluginDiagnostics(report, "src/app-server/protocol/server-requests.ts")).toEqual([]);
   });
 
+  it("keeps TSX files in rendering-owned source folders", async () => {
+    const cwd = await tempBiomeWorkspace(["no-misplaced-tsx.grit"]);
+    await writeFile(
+      path.join(cwd, "src/features/chat/application/state/view.tsx"),
+      `
+export const value = <div />;
+`.trimStart(),
+    );
+    await writeFile(
+      path.join(cwd, "src/domain/threads/view.tsx"),
+      `
+export const value = <span />;
+`.trimStart(),
+    );
+    await writeFile(
+      path.join(cwd, "src/features/chat/ui/message.tsx"),
+      `
+export const value = <article />;
+`.trimStart(),
+    );
+    await writeFile(
+      path.join(cwd, "src/settings/section.tsx"),
+      `
+export const value = <section />;
+`.trimStart(),
+    );
+    await writeFile(
+      path.join(cwd, "src/shared/ui/diff.tsx"),
+      `
+export const value = <pre />;
+`.trimStart(),
+    );
+
+    const report = biomeLint(
+      [
+        "src/features/chat/application/state/view.tsx",
+        "src/domain/threads/view.tsx",
+        "src/features/chat/ui/message.tsx",
+        "src/settings/section.tsx",
+        "src/shared/ui/diff.tsx",
+      ],
+      cwd,
+    );
+
+    expect(pluginMessages(report, "src/features/chat/application/state/view.tsx")).toEqual([
+      "Keep TSX files in UI, panel, settings, or explicit render bridge modules; non-rendering source should use .ts.",
+    ]);
+    expect(pluginMessages(report, "src/domain/threads/view.tsx")).toEqual([
+      "Keep TSX files in UI, panel, settings, or explicit render bridge modules; non-rendering source should use .ts.",
+    ]);
+    expect(pluginDiagnostics(report, "src/features/chat/ui/message.tsx")).toEqual([]);
+    expect(pluginDiagnostics(report, "src/settings/section.tsx")).toEqual([]);
+    expect(pluginDiagnostics(report, "src/shared/ui/diff.tsx")).toEqual([]);
+  });
+
   it("keeps app-server protocol modules behind app-server and chat ingestion boundaries", async () => {
     const cwd = await tempBiomeWorkspace(["no-app-server-protocol-boundary-imports.grit"]);
     await writeFile(
@@ -792,6 +847,7 @@ async function tempBiomeWorkspace(plugins) {
   await mkdir(path.join(cwd, "src/features/chat/panel"), { recursive: true });
   await mkdir(path.join(cwd, "src/features/chat/panel/surface"), { recursive: true });
   await mkdir(path.join(cwd, "src/features/chat/ui"), { recursive: true });
+  await mkdir(path.join(cwd, "src/settings"), { recursive: true });
   await mkdir(path.join(cwd, "src/domain/threads"), { recursive: true });
   await mkdir(path.join(cwd, "src/app-server/connection"), { recursive: true });
   await mkdir(path.join(cwd, "src/app-server/protocol"), { recursive: true });

tests/shared/ui/diff.test.ts

@@ -1,11 +1,11 @@
 import { describe, expect, it } from "vitest";
 
-import { displayDiffLines } from "../../../src/shared/diff/unified";
+import { unifiedDiffDisplayLines } from "../../../src/shared/ui/diff";
 
 describe("unified diff display lines", () => {
   it("simplifies git diff file headers for turn diff display", () => {
     expect(
-      displayDiffLines(
+      unifiedDiffDisplayLines(
         "diff --git a/days/2026-05-16.md b/days/2026-05-16.md\nindex 111..222\n--- a/days/2026-05-16.md\n+++ b/days/2026-05-16.md\n@@\n-old\n+new",
       ),
     ).toEqual([{ text: "days/2026-05-16.md", kind: "file" }, { text: "@@" }, { text: "-old" }, { text: "+new" }]);
@@ -13,7 +13,7 @@ describe("unified diff display lines", () => {
 
   it("keeps added-file diffs readable after simplifying headers", () => {
     expect(
-      displayDiffLines(
+      unifiedDiffDisplayLines(
         "diff --git a/new-note.md b/new-note.md\nnew file mode 100644\nindex 0000000..1111111\n--- /dev/null\n+++ b/new-note.md\n@@\n+hello",
       ),
     ).toEqual([{ text: "new-note.md", kind: "file" }, { text: "new file mode 100644" }, { text: "@@" }, { text: "+hello" }]);
@@ -21,7 +21,7 @@ describe("unified diff display lines", () => {
 
   it("keeps body lines that look like file markers after the hunk starts", () => {
     expect(
-      displayDiffLines(
+      unifiedDiffDisplayLines(
         "diff --git a/note.md b/note.md\nindex 111..222\n--- a/note.md\n+++ b/note.md\n@@\n+++ frontmatter\n--- removed marker",
       ),
     ).toEqual([{ text: "note.md", kind: "file" }, { text: "@@" }, { text: "+++ frontmatter" }, { text: "--- removed marker" }]);