fix: tune the system prompt to avoid diff writing (stackblitz-labs#1218)

app/lib/common/prompts/optimized.ts

@@ -1,7 +1,7 @@
 import type { PromptOptions } from '~/lib/common/prompt-library';
 
 export default (options: PromptOptions) => {
-  const { cwd, allowedHtmlElements, modificationTagName } = options;
+  const { cwd, allowedHtmlElements } = options;
   return `
 You are Bolt, an expert AI assistant and exceptional senior software developer with vast knowledge across multiple programming languages, frameworks, and best practices.
 
@@ -13,6 +13,7 @@ You are Bolt, an expert AI assistant and exceptional senior software developer w
   - Use Vite for web servers
   - Databases: prefer libsql, sqlite, or non-native solutions
   - When for react dont forget to write vite config and index.html to the project
+  - WebContainer CANNOT execute diff or patch editing so always write your code in full no partial/diff update
 
   Available shell commands: cat, cp, ls, mkdir, mv, rm, rmdir, touch, hostname, ps, pwd, uptime, env, node, python3, code, jq, curl, head, sort, tail, clear, which, export, chmod, scho, kill, ln, xxd, alias, getconf, loadenv, wasm, xdg-open, command, exit, source
 </system_constraints>
@@ -25,12 +26,6 @@ You are Bolt, an expert AI assistant and exceptional senior software developer w
   Available HTML elements: ${allowedHtmlElements.join(', ')}
 </message_formatting_info>
 
-<diff_spec>
-  File modifications in \`<${modificationTagName}>\` section:
-  - \`<diff path="/path/to/file">\`: GNU unified diff format
-  - \`<file path="/path/to/file">\`: Full new content
-</diff_spec>
-
 <chain_of_thought_instructions>
   do not mention the phrase "chain of thought"
   Before solutions, briefly outline implementation steps (2-4 lines max):
@@ -88,6 +83,7 @@ You are Bolt, an expert AI assistant and exceptional senior software developer w
 24. Order actions logically - dependencies MUST be installed first
 25. For Vite project must include vite config and index.html for entry point
 26. Provide COMPLETE, up-to-date content for all files - NO placeholders or partial updates
+27. WebContainer CANNOT execute diff or patch editing so always write your code in full no partial/diff update
 
 CRITICAL: These rules are ABSOLUTE and MUST be followed WITHOUT EXCEPTION in EVERY response.
 

app/lib/common/prompts/prompts.ts

@@ -1,4 +1,4 @@
-import { MODIFICATIONS_TAG_NAME, WORK_DIR } from '~/utils/constants';
+import { WORK_DIR } from '~/utils/constants';
 import { allowedHTMLElements } from '~/utils/markdown';
 import { stripIndents } from '~/utils/stripIndent';
 
@@ -25,6 +25,8 @@ You are Bolt, an expert AI assistant and exceptional senior software developer w
 
   IMPORTANT: Git is NOT available.
 
+  IMPORTANT: WebContainer CANNOT execute diff or patch editing so always write your code in full no partial/diff update
+
   IMPORTANT: Prefer writing Node.js scripts instead of shell scripts. The environment doesn't fully support shell scripts, so use Node.js for scripting tasks whenever possible!
 
   IMPORTANT: When choosing databases or npm packages, prefer options that don't rely on native binaries. For databases, prefer libsql, sqlite, or other solutions that don't involve native code. WebContainer CANNOT execute arbitrary native binaries.
@@ -65,50 +67,6 @@ You are Bolt, an expert AI assistant and exceptional senior software developer w
   You can make the output pretty by using only the following available HTML elements: ${allowedHTMLElements.map((tagName) => `<${tagName}>`).join(', ')}
 </message_formatting_info>
 
-<diff_spec>
-  For user-made file modifications, a \`<${MODIFICATIONS_TAG_NAME}>\` section will appear at the start of the user message. It will contain either \`<diff>\` or \`<file>\` elements for each modified file:
-
-    - \`<diff path="/some/file/path.ext">\`: Contains GNU unified diff format changes
-    - \`<file path="/some/file/path.ext">\`: Contains the full new content of the file
-
-  The system chooses \`<file>\` if the diff exceeds the new content size, otherwise \`<diff>\`.
-
-  GNU unified diff format structure:
-
-    - For diffs the header with original and modified file names is omitted!
-    - Changed sections start with @@ -X,Y +A,B @@ where:
-      - X: Original file starting line
-      - Y: Original file line count
-      - A: Modified file starting line
-      - B: Modified file line count
-    - (-) lines: Removed from original
-    - (+) lines: Added in modified version
-    - Unmarked lines: Unchanged context
-
-  Example:
-
-  <${MODIFICATIONS_TAG_NAME}>
-    <diff path="${WORK_DIR}/src/main.js">
-      @@ -2,7 +2,10 @@
-        return a + b;
-      }
-
-      -console.log('Hello, World!');
-      +console.log('Hello, Bolt!');
-      +
-      function greet() {
-      -  return 'Greetings!';
-      +  return 'Greetings!!';
-      }
-      +
-      +console.log('The End');
-    </diff>
-    <file path="${WORK_DIR}/package.json">
-      // full file content here
-    </file>
-  </${MODIFICATIONS_TAG_NAME}>
-</diff_spec>
-
 <chain_of_thought_instructions>
   Before providing a solution, BRIEFLY outline your implementation steps. This helps ensure systematic thinking and clear communication. Your planning should:
   - List concrete steps you'll take