refactor(coding-agent): streamlined codebase by deduplicating helper logic and shims

- Consolidated duplicated inline thinking level comparisons into a unified `concreteThinkingLevel` helper.
- Enhanced legacy tool shims to respect isolated session settings and support legacy options.
- Cleaned up redundant UI render requests and extra status-line updates.
- Refactored `grep` tool shim to configure context dynamically via isolated settings.
- Disabled platform-incompatible shell shim tests on Windows environments.

packages/coding-agent/src/utils/commit-message-generator.ts

@@ -12,7 +12,7 @@ import { getModelMatchPreferences, resolveModelRoleValue } from "../config/model
 import type { Settings } from "../config/settings";
 import MODEL_PRIO from "../priority.json" with { type: "json" };
 import commitSystemPrompt from "../prompts/system/commit-message-system.md" with { type: "text" };
-import { AUTO_THINKING, toReasoningEffort } from "../thinking";
+import { concreteThinkingLevel, toReasoningEffort } from "../thinking";
 
 const COMMIT_SYSTEM_PROMPT = prompt.render(commitSystemPrompt);
 const MAX_DIFF_CHARS = 4000;
@@ -56,10 +56,7 @@ function getSmolModelCandidates(
 		settings,
 		matchPreferences,
 	});
-	addCandidate(
-		configuredSmol.model,
-		configuredSmol.thinkingLevel === AUTO_THINKING ? undefined : configuredSmol.thinkingLevel,
-	);
+	addCandidate(configuredSmol.model, concreteThinkingLevel(configuredSmol.thinkingLevel));
 
 	for (const pattern of MODEL_PRIO.smol) {
 		const needle = pattern.toLowerCase();