Implemented the next missing parity slice around clearing session env vars on /clear.

Wires clear_session_env_vars() into LocalCodingAgent.clear_runtime_state so the
/clear slash command now drops session-scoped env vars alongside the rest of the
ephemeral runtime state, matching commands/clear/caches.ts:127.

PARITY_CHECKLIST.md

@@ -707,7 +707,7 @@ Done:
 - [x] Basic git status snapshot
 - [x] Basic shell/subprocess handling
 - [x] Bundled small portable utilities — `utils/array.ts`, `utils/set.ts`, `utils/objectGroupBy.ts`, `utils/xml.ts`, `utils/uuid.ts` ported in `src/small_utils.py`
-- [x] Session-scoped env-var registry (`utils/sessionEnvVars.ts`) ported in `src/session_env_vars.py` and merged into spawned subprocess env via `_build_subprocess_env` (mirrors `utils/shell/bashProvider.ts`)
+- [x] Session-scoped env-var registry (`utils/sessionEnvVars.ts`) ported in `src/session_env_vars.py`, merged into spawned subprocess env via `_build_subprocess_env` (mirrors `utils/shell/bashProvider.ts`), and dropped on `/clear` via `clear_runtime_state` (mirrors `commands/clear/caches.ts`)
 - [x] Display formatters from `utils/format.ts` (`formatFileSize`, `formatSecondsShort`, `formatDuration`, `formatNumber`, `formatTokens`) ported in `src/format_utils.py`
 
 Missing major utility categories:

src/agent_runtime.py

@@ -67,6 +67,7 @@ from .team_runtime import TeamRuntime
 from .tokenizer_runtime import describe_token_counter
 from .workflow_runtime import WorkflowRuntime
 from .worktree_runtime import WorktreeRuntime
+from .session_env_vars import clear_session_env_vars
 from .session_store import (
     StoredAgentSession,
     load_agent_session,
@@ -249,6 +250,8 @@ class LocalCodingAgent:
         self.resume_source_session_id = None
         if self.plugin_runtime is not None:
             self.plugin_runtime.restore_session_state({})
+        # Mirror commands/clear/caches.ts: drop session-scoped env vars on /clear.
+        clear_session_env_vars()
 
     def build_prompt_context(self, scratchpad_directory: Path | None = None):
         return build_prompt_context(

tests/test_agent_runtime.py

@@ -318,6 +318,27 @@ class AgentRuntimeTests(unittest.TestCase):
         self.assertEqual(result.tool_calls, 0)
         self.assertIn('# Permissions', result.final_output)
 
+    def test_clear_runtime_state_drops_session_env_vars(self) -> None:
+        from src.session_env_vars import (
+            clear_session_env_vars,
+            get_session_env_vars,
+            set_session_env_var,
+        )
+
+        clear_session_env_vars()
+        try:
+            with tempfile.TemporaryDirectory() as tmp_dir:
+                agent = LocalCodingAgent(
+                    model_config=ModelConfig(model='Qwen/Qwen3-Coder-30B-A3B-Instruct'),
+                    runtime_config=AgentRuntimeConfig(cwd=Path(tmp_dir)),
+                )
+                set_session_env_var('CLAW_CLEAR_TEST', 'before')
+                self.assertEqual(get_session_env_vars()['CLAW_CLEAR_TEST'], 'before')
+                agent.clear_runtime_state()
+                self.assertNotIn('CLAW_CLEAR_TEST', get_session_env_vars())
+        finally:
+            clear_session_env_vars()
+
     def test_agent_persists_session_and_can_resume(self) -> None:
         responses = [
             {