feat(aikit): declare tool changes as transcript system messages

CHANGELOG.md

@@ -25,10 +25,12 @@ This file is the canonical source for unreleased changes and published release n
 
 - A turn started for a prompt that was cancelled just before it joined the conversation no longer asks the model anything.
 - A prompt changed, cancelled or sent again while it was being taken in no longer fails the run; the run takes in the prompt as it now stands.
+- GitHub Copilot lists only the models its login can reach, by the `availableModelIds` recorded at login. A settings model that aliases another is matched by its API id.
 
 #### Internal
 
 - Migrations add `session_input.cancelled_seq`, and `session.execution` and `session.restarts`.
+- Stored context messages are user and assistant messages only; a stored system message fails to decode with "system messages are not stored as entries".
 - Tests use `gpt-6-luna` in place of the deprecated `gpt-5.5`.
 
 ### @codeworksh/cli
@@ -43,15 +45,39 @@ This file is the canonical source for unreleased changes and published release n
 #### Fixed
 
 - Ctrl+C on `codework run` without `--server` stops the run as a user stop, so `codework serve` does not resume it later.
+- `model.list` lists only the GitHub Copilot models the login can reach.
 
 #### Internal
 
 - Tests use `gpt-6-luna` in place of the deprecated `gpt-5.5`.
 
 ### @codeworksh/aikit
 
+#### Added
+
+- Transcript system messages change the tools mid-conversation: `Message.createSystemMessage({ toolsAdded?, toolsRemoved?, metadata? })`. `Context.tools` is the initial set. OpenAI Codex and GitHub Copilot Responses models that support it declare every tool in place, in `additional_tools` items, and announce removals as text, so the cached prompt prefix holds across tool changes; models with tool search only get later additions as a tool search result; every other model gets the current tools top-level.
+- `Transcript` helpers: `getCurrentTools`, `getDeclaredTools`, `getToolStateChanges`, `declarationsEqual`, `toToolDeclaration` and `resolveTranscriptTools`.
+- `filterGitHubCopilotModels` keeps the catalog models a Copilot login can reach.
+- GitHub Copilot GPT models turn reasoning off with `reasoning.effort: "none"` where OpenAI accepts it, such as gpt-5.3-codex, gpt-5.6-luna and gpt-6-luna.
+
+#### Changed
+
+- GitHub Copilot Responses requests go through aikit's own Responses model, shared with OpenAI Codex. They carry `prompt_cache_key` from the session id, put the system prompt in a developer message, and send `max_output_tokens` of at least 16.
+- Copilot's 1M-token context list now holds claude-fable-5, claude-opus-4.8, claude-opus-5, claude-opus-5.5, claude-sonnet-4.6, claude-sonnet-5, gpt-5.3-codex, gpt-6-astra, gpt-6-luna and gpt-6-sol.
+
+#### Removed
+
+- `ToolCall.addedToolNames`. A system message's `toolsAdded` takes its place, and token estimates count it.
+
 #### Fixed
 
+- GitHub Copilot Claude models that cannot disable thinking (Opus 5.5, Sonnet 5.5, Fable 5) no longer fail with thinking off; the request leaves thinking out.
+- A GitHub Copilot Responses tool call no longer splits into an empty call and a call with the arguments; Copilot changes the item id on every stream event.
+- GitHub Copilot Grok models no longer fail on a request without tools: `tool_choice` and `parallel_tool_calls` are sent only when the call names a tool choice. OpenAI Codex still sends both on every request.
+- A provider error the adapter cannot parse keeps its message and code, read from the response body. Copilot's Claude route reported "bad Request" for a model the account cannot use.
+- A grammar tool's earlier calls replay as grammar calls after the tool is removed.
+- A request limited by `activeTools` sends no tools outside that list.
+
 - `modelgen` leaves out providers with no models instead of writing them as empty entries.
 - Images in a failed tool result reach the model instead of being dropped. On the Anthropic wire the result is sent as text with `(image attached after the tool results)`, and the images follow the turn's tool results under `Images from the error result of tool call <id> (<name>):`. Other wires keep the images in the result; there the AI SDK sends it without an error flag.
 - On Chat Completions wires (OpenAI-compatible, Copilot chat, OpenAI with `method: chat`) and Gemini before 3, tool result images are sent in a user message after the tool results. Chat Completions sent them as JSON text, and Gemini before 3 lost the function response of a result with only images.

packages/aikit/src/cli/modelgen.ts

@@ -288,6 +288,13 @@ const OPENAI_LONG_CONTEXT_PRICING_MODELS = new Set([
 	"gpt-5.5-pro",
 ]);
 
+function openAiAcceptsNoReasoning(id: string): boolean {
+	return (
+		OPENAI_RESPONSES_NONE_REASONING_MODELS.has(id) ||
+		(OPENAI_GPT6_MODELS.has(id) && !OPENAI_GPT6_NO_NONE_MODELS.has(id))
+	);
+}
+
 function isOpenAiResponses(model: Model.Info): boolean {
 	return model.protocol === Model.KnownProviderEnum.openai || model.protocol === Model.KnownProviderEnum.openaiCodex;
 }
@@ -494,6 +501,20 @@ const OPENAI_CODEX_ADDITIONAL_TOOLS_MODEL_IDS = new Set([
 	"gpt-6-sol",
 	"gpt-6.1-sol",
 ]);
+// Copilot passes `additional_tools` items through to OpenAI for these Responses models.
+const GITHUB_COPILOT_ADDITIONAL_TOOLS_MODEL_IDS = new Set([
+	"gpt-5.4",
+	"gpt-5.4-mini",
+	"gpt-5.4-pro",
+	"gpt-5.5",
+	"gpt-5.6-sol",
+	"gpt-5.6-terra",
+	"gpt-5.6-luna",
+	"gpt-6-astra",
+	"gpt-6-sol",
+	"gpt-6-luna",
+	"gpt-6.1-sol",
+]);
 // Checked live: the Codex backend accepts reasoning.effort "none" for these.
 const OPENAI_CODEX_NONE_REASONING_MODEL_IDS = new Set(["gpt-5.6-luna", "gpt-6-luna", "gpt-6-sol"]);
 
@@ -557,21 +578,20 @@ const GITHUB_COPILOT_EXTENDED_CONTEXT = 1_000_000;
 // models as supporting the extended 1 million token context window (pi).
 const GITHUB_COPILOT_EXTENDED_CONTEXT_MODELS = new Set([
 	"claude-fable-5",
-	"claude-opus-4.6",
-	"claude-opus-4.7",
 	"claude-opus-4.8",
 	"claude-opus-5",
+	"claude-opus-5.5",
 	"claude-sonnet-4.6",
 	"claude-sonnet-5",
 	"gpt-5.3-codex",
-	"gpt-5.4",
-	"gpt-5.5",
+	"gpt-6-astra",
+	"gpt-6-luna",
+	"gpt-6-sol",
 ]);
 
 // Checked manually against the authenticated GitHub Copilot /models endpoint
 // (pi). Narrow corrections over models.dev metadata, not a catalog snapshot.
 const GITHUB_COPILOT_THINKING_LEVEL_OVERRIDES: Record<string, ThinkingLevelMap> = {
-	"claude-opus-4.7": { minimal: "low" },
 	"claude-opus-4.8": { minimal: "low" },
 	"claude-opus-5": { minimal: "low" },
 	"claude-sonnet-4.6": { minimal: "low", max: "max" },
@@ -610,8 +630,8 @@ function githubCopilotThinkingLevels(model: ModelsDevModel, method: Model.APIMet
 	const listed = modelsDevEfforts(model);
 	const efforts = listed ? new Set(listed) : undefined;
 	const map: ThinkingLevelMap = {};
-	// Copilot rejects `reasoningEffort: "none"` (pi), and the chat route has no
-	// reasoning control, so only Messages models can disable thinking.
+	// Off is opt-in per model on Responses (Grok and MAI reject "none"), and the chat route
+	// has no reasoning control.
 	if (method !== Model.APIMethodEnum.messages) map.off = null;
 	if (!efforts) return Object.keys(map).length > 0 ? map : undefined;
 
@@ -650,19 +670,6 @@ export function githubCopilotBuiltInModels(provider: ModelsDevProvider | undefin
 			api: { id, url: GITHUB_COPILOT_BASE_URL, method },
 			providerOptionsKey: GITHUB_COPILOT_PROVIDER_ID,
 			protocol: Model.KnownProviderEnum.githubCopilot,
-			// Copilot's Responses route requires store=false + encrypted reasoning
-			// content for thinking to round-trip.
-			...(method === Model.APIMethodEnum.responses
-				? {
-						providerOptions: {
-							...base.providerOptions,
-							[GITHUB_COPILOT_PROVIDER_ID]: {
-								store: false,
-								include: ["reasoning.encrypted_content"],
-							},
-						},
-					}
-				: {}),
 		};
 
 		if (GITHUB_COPILOT_EXTENDED_CONTEXT_MODELS.has(id)) info.contextWindow = GITHUB_COPILOT_EXTENDED_CONTEXT;
@@ -675,13 +682,21 @@ export function githubCopilotBuiltInModels(provider: ModelsDevProvider | undefin
 		if (method === Model.APIMethodEnum.responses && gpt !== null && Number(gpt[1]) >= 5) {
 			mergeCompat(info, { supportsOpenAIGrammarTools: true });
 		}
+		if (method === Model.APIMethodEnum.responses && GITHUB_COPILOT_ADDITIONAL_TOOLS_MODEL_IDS.has(id)) {
+			mergeCompat(info, { supportsAdditionalTools: true });
+		}
 		if (id.startsWith("gpt-5")) mergeThinkingLevelMap(info, { off: null, minimal: "low" });
 		if (id.includes("fable-5")) mergeThinkingLevelMap(info, { off: null, xhigh: "xhigh", max: "max" });
 
 		const levels = githubCopilotThinkingLevels(source, method);
 		if (levels) mergeThinkingLevelMap(info, levels);
 		const override = GITHUB_COPILOT_THINKING_LEVEL_OVERRIDES[id];
 		if (override) mergeThinkingLevelMap(info, override);
+		// Copilot forwards reasoning.effort to OpenAI unchanged, so the GPT models OpenAI lets
+		// turn reasoning off take "none" here too (checked live).
+		if (method === Model.APIMethodEnum.responses && openAiAcceptsNoReasoning(id)) {
+			mergeThinkingLevelMap(info, { off: "none" });
+		}
 
 		models[id] = info;
 	}

packages/aikit/src/index.ts

@@ -5,6 +5,7 @@ export * as Protocol from "./llm/protocol.ts";
 export { getEnvApiKey } from "./llm/runtime.ts";
 export { ThinkingBudgets } from "./llm/shared.ts";
 export * as Message from "./message/message.ts";
+export * as Transcript from "./message/transcript.ts";
 export * as Model from "./model/model.ts";
 export { stream } from "./stream.ts";
 export { createAssistantMessageEventStream, EventStream } from "./utils/eventstream.ts";

packages/aikit/src/llm/failure.ts

@@ -78,9 +78,20 @@ const retryAfter = (headers: Record<string, string> | undefined): number | undef
 	if (Number.isFinite(date)) return Math.max(0, date - Date.now());
 };
 
+const parseJson = (text: string | undefined): unknown => {
+	if (text === undefined) return undefined;
+	try {
+		return JSON.parse(text);
+	} catch {
+		return undefined;
+	}
+};
+
 const apiMetadata = (error: APICallError): Metadata => {
-	const code = errorCode(error.data);
-	const data = record(error.data);
+	// An adapter fronting another vendor's error shape (Copilot's OpenAI-style errors on the
+	// Anthropic route) leaves `data` unset; the raw body still carries the message and code.
+	const data = record(error.data) ?? record(parseJson(error.responseBody));
+	const code = errorCode(data);
 	const nested = record(data?.error);
 	const structuredMessage = nonEmptyString(data?.message) ?? nonEmptyString(nested?.message);
 	const message = normalizeMessage(

packages/aikit/src/llm/options.ts

@@ -18,7 +18,8 @@ import type { OpenRouterProviderOptions, OpenRouterProviderSettings } from "@ope
 import { Type, type Static } from "typebox";
 import * as Model from "../model/model.ts";
 import type { GitHubCopilotProviderSettings } from "../providers/github-copilot/index.ts";
-import type { OpenAICodexLanguageModelOptions, OpenAICodexProviderSettings } from "../providers/openai-codex/index.ts";
+import type { OpenAICodexProviderSettings } from "../providers/openai-codex/index.ts";
+import type { ResponsesLanguageModelOptions } from "../providers/responses/model.ts";
 import type * as Protocol from "./protocol.ts";
 import { SharedOptions, ThinkingBudgets } from "./shared.ts";
 
@@ -68,7 +69,7 @@ type OpenAICompatibleLanguageOptions =
 type XaiLanguageOptions = XaiLanguageModelResponsesOptions;
 type GitHubCopilotLanguageOptions =
 	| AnthropicLanguageModelOptions
-	| OpenAILanguageModelResponsesOptions
+	| ResponsesLanguageModelOptions
 	| OpenAICompatibleLanguageModelChatOptions;
 
 export type OpenAIOptions = AISDKOptions<OpenAIProviderSettings, { openai?: OpenAILanguageOptions }>;
@@ -82,7 +83,7 @@ export type OpenAICompatibleOptions = AISDKOptions<
 >;
 export type OpenAICodexOptions = AISDKOptions<
 	OpenAICodexProviderSettings,
-	{ "openai-codex"?: OpenAICodexLanguageModelOptions }
+	{ "openai-codex"?: ResponsesLanguageModelOptions }
 >;
 export type GitHubCopilotOptions = AISDKOptions<
 	GitHubCopilotProviderSettings,

packages/aikit/src/llm/provider.ts

@@ -79,22 +79,28 @@ export async function resolveAISDKLanguageModel(
 		}
 	}
 
+	const cacheDisabled =
+		options.cacheRetention === "none" ||
+		(typeof process !== "undefined" && process.env.CODEWORK_CACHE_RETENTION === "none");
+	// Our own Responses model (Codex, Copilot `/responses`) reads image support from compat.
+	const responsesCompat = () => ({
+		...model.compat,
+		supportsImages: model.input.includes("image"),
+		...(typeof factoryOptions.compat === "object" && factoryOptions.compat !== null ? factoryOptions.compat : {}),
+	});
+
 	if (npm === "@codeworksh/ai-sdk-openai-codex") {
 		// Codex uses the session id for the session-id header and prompt cache key.
-		const cacheDisabled =
-			options.cacheRetention === "none" ||
-			(typeof process !== "undefined" && process.env.CODEWORK_CACHE_RETENTION === "none");
 		if (options.sessionId && !cacheDisabled) factoryOptions.sessionId ??= options.sessionId;
-		factoryOptions.compat = {
-			...model.compat,
-			supportsImages: model.input.includes("image"),
-			...(typeof factoryOptions.compat === "object" && factoryOptions.compat !== null ? factoryOptions.compat : {}),
-		};
+		factoryOptions.compat = responsesCompat();
 	}
 
 	if (npm === "@codeworksh/ai-sdk-github-copilot") {
-		// Copilot uses the session id for X-Interaction-Id request grouping.
+		// Copilot uses the session id for X-Interaction-Id request grouping, and as the
+		// Responses prompt cache key.
 		if (options.sessionId) factoryOptions.sessionId ??= options.sessionId;
+		if (options.sessionId && !cacheDisabled) factoryOptions.promptCacheKey ??= options.sessionId;
+		factoryOptions.compat = responsesCompat();
 
 		const budgetField = Model.thinkingTokenBudgetField(model);
 		if (budgetField && thinkingTokenBudget !== undefined && thinkingTokenBudget > 0) {

packages/aikit/src/llm/stream.ts

@@ -1,6 +1,7 @@
 import { APICallError } from "@ai-sdk/provider";
 import { RetryError, streamText, type TextStreamPart, type ToolSet } from "ai";
 import * as Message from "../message/message.ts";
+import * as Transcript from "../message/transcript.ts";
 import * as Model from "../model/model.ts";
 import { AssistantMessageEventStream } from "../utils/eventstream.ts";
 import { compact } from "../utils/helpers.ts";
@@ -15,9 +16,11 @@ import * as Thinking from "./thinking.ts";
 import {
 	googleThoughtSignature,
 	convertMessages,
+	isOwnResponses,
 	convertTools,
 	createAssistantMessage,
 	encodeOpenAIReasoningSignature,
+	grammarToolInputProperties,
 	mapFinishReason,
 	mapUsage,
 	toolCallFromPart,
@@ -79,11 +82,18 @@ function cacheProviderOptions(model: Model.Info, options: RuntimeOptions): Provi
 	return {};
 }
 
-function resolveProviderOptions(model: Model.Info, options: RuntimeOptions, plan: Thinking.Plan): ProviderOptionBag {
+function resolveProviderOptions(
+	model: Model.Info,
+	context: Message.Context,
+	options: RuntimeOptions,
+	plan: Thinking.Plan,
+): ProviderOptionBag {
+	const grammars = grammarToolInputProperties(context, model, options.method);
 	return mergeProviderOptions(
 		model.providerOptions as ProviderOptionBag | undefined,
 		cacheProviderOptions(model, options),
 		Thinking.reasoningProviderOptions(model, plan),
+		grammars === undefined ? undefined : { [Model.optionsKey(model)]: { grammarToolInputProperties: grammars } },
 		options.providerOptions as ProviderOptionBag | undefined,
 	);
 }
@@ -92,9 +102,10 @@ function partIndex(output: Message.AssistantMessage, block: StreamBlock): number
 	return output.parts.indexOf(block as Message.AssistantMessage["parts"][number]);
 }
 
-function openAICodexMetadata(value: unknown): Record<string, unknown> | undefined {
+/** Metadata our Responses transport attaches under the model's provider key. */
+function responsesMetadata(value: unknown, model: Model.Info): Record<string, unknown> | undefined {
 	if (typeof value !== "object" || value === null || Array.isArray(value)) return undefined;
-	const metadata = (value as Record<string, unknown>)["openai-codex"];
+	const metadata = (value as Record<string, unknown>)[Model.optionsKey(model)];
 	return typeof metadata === "object" && metadata !== null && !Array.isArray(metadata)
 		? (metadata as Record<string, unknown>)
 		: undefined;
@@ -206,6 +217,7 @@ function finishToolInput(output: Message.AssistantMessage, id: string, stream: A
 function finalizeToolCall(
 	output: Message.AssistantMessage,
 	part: Extract<TextStreamPart<ToolSet>, { type: "tool-call" }>,
+	model: Model.Info,
 	stream: AssistantMessageEventStream,
 ): void {
 	const existing = output.parts.find((item) => item.type === "toolCall" && item.callID === part.toolCallId) as
@@ -216,7 +228,7 @@ function finalizeToolCall(
 	block.name = part.toolName;
 	block.arguments =
 		typeof part.input === "object" && part.input !== null ? (part.input as Record<string, unknown>) : {};
-	const namespace = openAICodexMetadata(part.providerMetadata)?.namespace;
+	const namespace = responsesMetadata(part.providerMetadata, model)?.namespace;
 	const thoughtSignature = googleThoughtSignature(part.providerMetadata);
 	if (thoughtSignature) block.thoughtSignature = thoughtSignature;
 	if (typeof namespace === "string") block.namespace = namespace;
@@ -262,7 +274,7 @@ function handlePart(
 			break;
 		}
 		case "text-end": {
-			const messageId = openAICodexMetadata(part.providerMetadata)?.messageId;
+			const messageId = responsesMetadata(part.providerMetadata, model)?.messageId;
 			finishTextBlock(output, part.id, stream, typeof messageId === "string" ? messageId : undefined);
 			break;
 		}
@@ -288,7 +300,7 @@ function handlePart(
 			break;
 		}
 		case "reasoning-end": {
-			const reasoningItem = openAICodexMetadata(part.providerMetadata)?.reasoningItem;
+			const reasoningItem = responsesMetadata(part.providerMetadata, model)?.reasoningItem;
 			const openAISignature = encodeOpenAIReasoningSignature(part.providerMetadata);
 			finishThinkingBlock(
 				output,
@@ -317,7 +329,7 @@ function handlePart(
 			finishToolInput(output, part.id, stream);
 			break;
 		case "tool-call":
-			finalizeToolCall(output, part, stream);
+			finalizeToolCall(output, part, model, stream);
 			break;
 		case "start-step":
 			stampProviderThinkingLevel(output, part.request.body);
@@ -402,9 +414,10 @@ export const stream: Protocol.StreamFunction<Model.KnownProviderEnum, typeof Opt
 		try {
 			const plan = Thinking.resolvePlan(model, context, runtimeOptions);
 			const languageModel = await resolveAISDKLanguageModel(model, runtimeOptions, plan.budget);
-			const tools = convertTools(context.tools, model);
-			const messages = convertMessages(context, model, runtimeOptions.method);
-			const providerOptions = resolveProviderOptions(model, runtimeOptions, plan) as Parameters<
+			// Every tool callable now, so calls to tools declared in place still parse.
+			const tools = convertTools(Transcript.getCurrentTools(context), model, runtimeOptions.method);
+			const messages = convertMessages(context, model, runtimeOptions.method, runtimeOptions.activeTools);
+			const providerOptions = resolveProviderOptions(model, context, runtimeOptions, plan) as Parameters<
 				typeof streamText<ToolSet>
 			>[0]["providerOptions"];
 			const pricing: Pricing = {
@@ -418,8 +431,11 @@ export const stream: Protocol.StreamFunction<Model.KnownProviderEnum, typeof Opt
 
 			let params: Parameters<typeof streamText<ToolSet>>[0] = compact({
 				model: languageModel,
-				system: context.systemPrompt,
+				// Our own Responses transport receives the system prompt among the messages.
+				system: isOwnResponses(model, runtimeOptions.method) ? undefined : context.systemPrompt,
 				messages,
+				// Tool changes declared in place travel as system messages.
+				allowSystemInMessages: messages.some((message) => message.role === "system") || undefined,
 				tools,
 				toolChoice: runtimeOptions.toolChoice as Parameters<typeof streamText<ToolSet>>[0]["toolChoice"],
 				activeTools,