fix: clean up Codex thinking level handling

- Remove per-thinking-level model variants (gpt-5.2-codex-high, etc.)
- Remove thinkingLevels from Model type
- Provider clamps reasoning effort internally
- Omit reasoning field when thinking is off

fixes #472

packages/coding-agent/src/core/agent-session.ts

@@ -1007,16 +1007,10 @@ export class AgentSession {
 
 	/**
 	 * Get available thinking levels for current model.
+	 * The provider will clamp to what the specific model supports internally.
 	 */
 	getAvailableThinkingLevels(): ThinkingLevel[] {
 		if (!this.supportsThinking()) return ["off"];
-
-		const modelLevels = this.model?.thinkingLevels;
-		if (modelLevels && modelLevels.length > 0) {
-			const withOff: ThinkingLevel[] = ["off", ...modelLevels];
-			return THINKING_LEVELS_WITH_XHIGH.filter((level) => withOff.includes(level));
-		}
-
 		return this.supportsXhighThinking() ? THINKING_LEVELS_WITH_XHIGH : THINKING_LEVELS;
 	}
 

packages/coding-agent/src/core/model-registry.ts

@@ -18,16 +18,6 @@ import type { AuthStorage } from "./auth-storage.js";
 
 const Ajv = (AjvModule as any).default || AjvModule;
 
-const ThinkingLevelsSchema = Type.Array(
-	Type.Union([
-		Type.Literal("minimal"),
-		Type.Literal("low"),
-		Type.Literal("medium"),
-		Type.Literal("high"),
-		Type.Literal("xhigh"),
-	]),
-);
-
 // Schema for OpenAI compatibility settings
 const OpenAICompatSchema = Type.Object({
 	supportsStore: Type.Optional(Type.Boolean()),
@@ -50,7 +40,6 @@ const ModelDefinitionSchema = Type.Object({
 		]),
 	),
 	reasoning: Type.Boolean(),
-	thinkingLevels: Type.Optional(ThinkingLevelsSchema),
 	input: Type.Array(Type.Union([Type.Literal("text"), Type.Literal("image")])),
 	cost: Type.Object({
 		input: Type.Number(),
@@ -118,14 +107,6 @@ function resolveApiKeyConfig(keyConfig: string): string | undefined {
 	return keyConfig;
 }
 
-function normalizeCodexModelId(modelId: string): string {
-	const suffixes = ["-none", "-minimal", "-low", "-medium", "-high", "-xhigh"];
-	const normalized = modelId.toLowerCase();
-	const matchedSuffix = suffixes.find((suffix) => normalized.endsWith(suffix));
-	if (!matchedSuffix) return modelId;
-	return modelId.slice(0, modelId.length - matchedSuffix.length);
-}
-
 /**
  * Model registry - loads and manages models, resolves API keys via AuthStorage.
  */
@@ -349,7 +330,6 @@ export class ModelRegistry {
 					provider: providerName,
 					baseUrl: providerConfig.baseUrl!,
 					reasoning: modelDef.reasoning,
-					thinkingLevels: modelDef.thinkingLevels,
 					input: modelDef.input as ("text" | "image")[],
 					cost: modelDef.cost,
 					contextWindow: modelDef.contextWindow,
@@ -383,15 +363,7 @@ export class ModelRegistry {
 	 * Find a model by provider and ID.
 	 */
 	find(provider: string, modelId: string): Model<Api> | undefined {
-		const exact = this.models.find((m) => m.provider === provider && m.id === modelId);
-		if (exact) return exact;
-		if (provider === "openai-codex") {
-			const normalized = normalizeCodexModelId(modelId);
-			if (normalized !== modelId) {
-				return this.models.find((m) => m.provider === provider && m.id === normalized) ?? undefined;
-			}
-		}
-		return undefined;
+		return this.models.find((m) => m.provider === provider && m.id === modelId);
 	}
 
 	/**

packages/coding-agent/src/core/model-resolver.ts

@@ -102,18 +102,6 @@ export interface ParsedModelResult {
 	warning: string | undefined;
 }
 
-const THINKING_SUFFIXES = ["-none", "-minimal", "-low", "-medium", "-high", "-xhigh"];
-
-function stripThinkingSuffix(pattern: string): string {
-	const normalized = pattern.toLowerCase();
-	for (const suffix of THINKING_SUFFIXES) {
-		if (normalized.endsWith(suffix)) {
-			return pattern.slice(0, pattern.length - suffix.length);
-		}
-	}
-	return pattern;
-}
-
 /**
  * Parse a pattern to extract model and thinking level.
  * Handles models with colons in their IDs (e.g., OpenRouter's :exacto suffix).
@@ -134,14 +122,6 @@ export function parseModelPattern(pattern: string, availableModels: Model<Api>[]
 		return { model: exactMatch, thinkingLevel: "off", warning: undefined };
 	}
 
-	const normalizedPattern = stripThinkingSuffix(pattern);
-	if (normalizedPattern !== pattern) {
-		const normalizedMatch = tryMatchModel(normalizedPattern, availableModels);
-		if (normalizedMatch) {
-			return { model: normalizedMatch, thinkingLevel: "off", warning: undefined };
-		}
-	}
-
 	// No match - try splitting on last colon if present
 	const lastColonIndex = pattern.lastIndexOf(":");
 	if (lastColonIndex === -1) {