fix(atlas): tighten SHORT/LONG format instructions in description prompts

Small local models drifted off the two-section format. Restate it as an
explicit rule list instead of prose.

Author: cloudbridgeuy

crates/core/src/atlas/prompts.rs

@@ -15,15 +15,16 @@ fn format_symbol(sym: &Symbol) -> String {
 
 /// System prompt instructing the LLM to output SHORT:/LONG: format.
 pub fn file_system_prompt() -> &'static str {
-    "You are a code documentation assistant.\n\
-     Your response MUST start with SHORT: on the very first line. No preamble.\n\
-     Output exactly two sections:\n\n\
-     SHORT: A brief one-line description of the file (under 80 characters).\n\
-     LONG: A detailed description weaving in patterns, dependencies, and relationships.\n\n\
-     Example format:\n\
+    "You describe source code files. Respond ONLY in this exact format:\n\n\
+     SHORT: <one line, under 80 chars>\n\
+     LONG: <detailed description>\n\n\
+     Rules:\n\
+     - First line must be SHORT: followed by a brief description\n\
+     - Second line must be LONG: followed by a detailed description\n\
+     - No other text before SHORT:\n\
+     - Be factual, not creative\n\n\
      SHORT: CLI argument parser and validation\n\
-     LONG: Defines the command-line interface using clap, validates input flags, and maps them to internal config types.\n\n\
-     Be factual, not creative. Do not invent information beyond what the code shows."
+     LONG: Defines the command-line interface using clap, validates input flags, and maps them to internal config types."
 }
 
 /// Assemble an LLM prompt for describing a single file.
@@ -83,16 +84,16 @@ pub fn build_file_prompt(
 
 /// System prompt for directory descriptions. Static string.
 pub fn directory_system_prompt() -> &'static str {
-    "You are a code documentation assistant.\n\
-     Your response MUST start with SHORT: on the very first line. No preamble.\n\
-     Output exactly two sections:\n\n\
-     SHORT: A brief one-line description of the directory (under 80 characters).\n\
-     LONG: A detailed description covering the directory's role, what it contains, \
-     and how its contents relate to each other.\n\n\
-     Example format:\n\
+    "You describe source code directory contents. Respond ONLY in this exact format:\n\n\
+     SHORT: <one line, under 80 chars>\n\
+     LONG: <detailed description>\n\n\
+     Rules:\n\
+     - First line must be SHORT: followed by a brief description\n\
+     - Second line must be LONG: followed by a detailed description\n\
+     - No other text before SHORT:\n\
+     - Be factual, not creative\n\n\
      SHORT: Database access layer and query builders\n\
-     LONG: Contains the SQLite connection wrapper, CRUD methods for files and directories, and query helpers for tree and peek views.\n\n\
-     Be factual, not creative. Do not invent information beyond what the contents show."
+     LONG: Contains the SQLite connection wrapper, CRUD methods for files and directories, and query helpers for tree and peek views."
 }
 
 /// Build the user prompt for a directory description.