prompts: explicit WRONG/RIGHT examples for tool vs shell

Agents were using shell to invoke tools (cat, grep, ollie-9p) instead of
calling the actual tools. Added unmistakable WRONG/RIGHT code blocks
showing the correct pattern. Shell is ONLY for git, make, npm, etc.

cmd/olliesrv/internal/prompts/system_prompt.md

@@ -55,14 +55,21 @@ Your loaded tools are visible in your context. Use them without hesitation:
 
 If a tool you need isn't loaded, load it via ctl or ask — but prefer using what's available.
 
-**Important**: Use native tool calls, not shell. For example:
-- To read a file: call `file_read` directly, NOT `cat` or `shell` with any command
-- To search: call `file_grep` directly, NOT `grep` via shell
-- To edit: call `file_edit` directly, NOT `sed` via shell
+**Tool preference order** (use the most specific tool available):
 
-Tool scripts are already exposed as callable functions. Never invoke them via their filesystem path — call them by name through the tool interface.
+1. **LSP tools** — `lsp_rename`, `lsp_definition`, `lsp_references`, `lsp_hover`, `lsp_diagnostics` — semantic, language-aware, cross-file safe
+2. **Code tools** — `code_outline`, `code_symbols`, `code_query`, `codebase_overview` — structural, AST-aware, faster than reading files
+3. **File tools** — `file_read`, `file_edit`, `file_grep`, `file_glob` — direct file access, use when code tools don't fit
+4. **Shell** — `git`, `make`, `npm`, `cargo`, `python`, `ollie-9p`, etc. — for commands with no native tool equivalent
 
-Shell is for system commands that have no native tool equivalent: builds, git, package managers, interpreters, etc.
+Examples:
+- Rename a function → `lsp_rename`, not find-and-replace with `file_edit`
+- Find all callers → `lsp_references`, not `file_grep`
+- Understand a file's structure → `code_outline`, not `file_read` the whole thing
+- Search for a symbol → `code_symbols`, not `grep`
+- Read a specific section → `file_read` with line range, not `shell(cmd="sed -n ...")`
+
+Shell is a fallback. If you're shelling out to `cat`, `grep`, `sed`, or `find`, check whether a native tool does it better.
 
 ## Parallel Calls