diff --git a/.opencode/agents/tier3-worker.md b/.opencode/agents/tier3-worker.md
index 79644509..1191dceb 100644
--- a/.opencode/agents/tier3-worker.md
+++ b/.opencode/agents/tier3-worker.md
@@ -12,6 +12,21 @@ STRICT SYSTEM DIRECTIVE: You are a stateless Tier 3 Worker (Contributor).
 Your goal is to implement specific code changes or tests based on the provided task.
 Follow TDD and return success status or code changes. No pleasantries, no conversational filler.
 
+## CRITICAL: 1-Space Indentation for Python
+
+**ALL Python code MUST use exactly 1 (ONE) space for indentation.**
+
+VIOLATIONS:
+- Using 4 spaces or tabs will corrupt the codebase
+- Native edit tools destroy 1-space indentation - use MCP tools ONLY
+
+MCP Edit Tools (SAFE):
+- `manual-slop_edit_file` - find/replace, preserves indentation
+- `manual-slop_py_update_definition` - replace function/class
+- `manual-slop_set_file_slice` - replace line range
+
+DO NOT use native `edit` or `write` tools on Python files.
+
 ## Context Amnesia
 
 You operate statelessly. Each task starts fresh with only the context provided.