fix(frontend): harden render registry dispatch and test toolResultHasBody

Introduce UNKNOWN_DISPATCH_KEY sentinel with documented non-registration
rule. Guard renderToolUse/renderToolResult against null input; guard
toolResultHasBody similarly. Add Vitest coverage for sentinel, null args,
and toolResultHasBody contract used by sessions.js.

Author: clean6378-max-it

static/js/render/constants.js

@@ -0,0 +1,5 @@
+/**
+ * Sentinel when tool.name or result_type is missing.
+ * Used for fallback routing only — do not add UNKNOWN_DISPATCH_KEY to TOOL_*_RENDERERS.
+ */
+export const UNKNOWN_DISPATCH_KEY = 'unknown';

static/js/render/registry.js

@@ -11,6 +11,7 @@ import { renderWebFetchUse } from './tool_use/web_fetch.js';
 import { renderWebSearchUse } from './tool_use/web_search.js';
 import { renderToolUseFallback } from './tool_use/fallback.js';
 import { getToolSummary } from './tool_use/summary.js';
+import { UNKNOWN_DISPATCH_KEY } from './constants.js';
 
 import { renderBashResult } from './tool_result/bash.js';
 import { renderFileReadResult } from './tool_result/file_read.js';
@@ -71,11 +72,13 @@ function getToolResultRenderer(resultType) {
 }
 
 export function renderToolUse(tool) {
-    const name = tool.name || 'unknown';
+    if (!tool) return '';
+    const name = tool.name || UNKNOWN_DISPATCH_KEY;
     return getToolUseRenderer(name)(tool);
 }
 
 export function renderToolResult(parsed) {
-    const rt = parsed.result_type || 'unknown';
+    if (!parsed) return '';
+    const rt = parsed.result_type || UNKNOWN_DISPATCH_KEY;
     return getToolResultRenderer(rt)(parsed);
 }

static/js/render/registry.test.js

@@ -5,7 +5,9 @@ import {
     renderToolUse,
     renderToolResult,
     getToolSummary,
+    toolResultHasBody,
 } from './registry.js';
+import { UNKNOWN_DISPATCH_KEY } from './constants.js';
 import { renderWebFetchUse } from './tool_use/web_fetch.js';
 
 const CORE_TOOL_USE = ['Bash', 'Read', 'Write', 'Edit', 'Glob', 'Grep', 'Task', 'TodoWrite', 'AskUserQuestion', 'WebFetch', 'WebSearch'];
@@ -32,6 +34,10 @@ describe('TOOL_USE_RENDERERS', () => {
         }
     });
 
+    it('does not register the unknown dispatch sentinel as a tool renderer', () => {
+        expect(Object.prototype.hasOwnProperty.call(TOOL_USE_RENDERERS, UNKNOWN_DISPATCH_KEY)).toBe(false);
+    });
+
     it('renderBashUse escapes HTML in command', () => {
         const html = renderToolUse({
             name: 'Bash',
@@ -41,6 +47,11 @@ describe('TOOL_USE_RENDERERS', () => {
         expect(html).toContain('<script>');
     });
 
+    it('returns empty string for null or undefined tool', () => {
+        expect(renderToolUse(null)).toBe('');
+        expect(renderToolUse(undefined)).toBe('');
+    });
+
     it('renderReadUse escapes file path in body and summary', () => {
         const html = renderToolUse({
             name: 'Read',
@@ -73,6 +84,41 @@ describe('TOOL_RESULT_RENDERERS', () => {
         expect(html).toContain('Bash Result (unknown)');
         expect(html).not.toContain('undefined');
     });
+
+    it('returns empty string for null or undefined parsed', () => {
+        expect(renderToolResult(null)).toBe('');
+        expect(renderToolResult(undefined)).toBe('');
+    });
+});
+
+describe('toolResultHasBody', () => {
+    it('returns false for null or undefined', () => {
+        expect(toolResultHasBody(null)).toBe(false);
+        expect(toolResultHasBody(undefined)).toBe(false);
+    });
+
+    it('returns true for bash with stdout or stderr', () => {
+        expect(toolResultHasBody({ result_type: 'bash', stdout: 'ok' })).toBe(true);
+        expect(toolResultHasBody({ result_type: 'bash', stderr: 'err' })).toBe(true);
+        expect(toolResultHasBody({ result_type: 'bash' })).toBe(false);
+    });
+
+    it('returns false for summary-only result types', () => {
+        expect(toolResultHasBody({ result_type: 'file_read', file_path: '/a' })).toBe(false);
+        expect(toolResultHasBody({ result_type: 'glob', num_files: 3 })).toBe(false);
+    });
+
+    it('returns true for user_input and todo_write with todos', () => {
+        expect(toolResultHasBody({ result_type: 'user_input' })).toBe(true);
+        expect(toolResultHasBody({ result_type: 'todo_write', todos: [{ content: 'x' }] })).toBe(true);
+        expect(toolResultHasBody({ result_type: 'todo_write', todo_count: 1 })).toBe(false);
+    });
+
+    it('returns true for task when duration, retrieval, or description is set', () => {
+        expect(toolResultHasBody({ result_type: 'task', description: 'subagent' })).toBe(true);
+        expect(toolResultHasBody({ result_type: 'task', total_duration_ms: 100 })).toBe(true);
+        expect(toolResultHasBody({ result_type: 'task', status: 'completed' })).toBe(false);
+    });
 });
 
 describe('getToolSummary', () => {

static/js/render/tool_result/fallback.js

@@ -1,7 +1,8 @@
 import { finishToolResult } from './common.js';
+import { UNKNOWN_DISPATCH_KEY } from '../constants.js';
 
 export function renderToolResultFallback(parsed) {
-    const rt = parsed.result_type || 'unknown';
+    const rt = parsed.result_type || UNKNOWN_DISPATCH_KEY;
     const summary = `Tool result (${rt})`;
     return finishToolResult(summary, '');
 }

static/js/render/tool_result/utils.js

@@ -1,5 +1,8 @@
+import { UNKNOWN_DISPATCH_KEY } from '../constants.js';
+
 export function toolResultHasBody(parsed) {
-    const rt = parsed.result_type || 'unknown';
+    if (!parsed) return false;
+    const rt = parsed.result_type || UNKNOWN_DISPATCH_KEY;
     if (rt === 'bash') return !!(parsed.stdout || parsed.stderr);
     if (rt === 'todo_write') return !!(parsed.todos && parsed.todos.length);
     if (rt === 'user_input') return true;

static/js/render/tool_use/fallback.js

@@ -1,9 +1,10 @@
 import { esc, truncate } from '../../shared/utils.js';
 import { getToolSummary } from './summary.js';
 import { wrapToolUse } from './common.js';
+import { UNKNOWN_DISPATCH_KEY } from '../constants.js';
 
 export function renderToolUseFallback(tool) {
-    const name = tool.name || 'unknown';
+    const name = tool.name || UNKNOWN_DISPATCH_KEY;
     const inp = tool.input || {};
     const summary = getToolSummary(name, inp);
     const s = JSON.stringify(inp, null, 2);