Function createCtxReduceTool

packages/pi-plugin/src/tools/ctx-reduce.ts:65–183

(
	deps: CtxReduceToolDeps,
)

}

export function createCtxReduceTool(
	deps: CtxReduceToolDeps,
): ToolDefinition<typeof ParamsSchema> {
	return {
		name: "ctx_reduce",
		label: "Magic Context: Reduce",
		description: CTX_REDUCE_DESCRIPTION,
		parameters: ParamsSchema,
		async execute(
			_toolCallId,
			params: CtxReduceParams,
			_signal,
			_onUpdate,
			ctx,
		) {
			const sessionId = ctx.sessionManager.getSessionId();

			if (!params.drop) {
				return err("Error: 'drop' must be provided.");
			}

			let dropIds: number[] = [];
			try {
				dropIds = parseRangeString(params.drop);
			} catch (e) {
				return err(`Error: Invalid range syntax. ${(e as Error).message}`);
			}

			const allIds = [...new Set(dropIds)];

			const allTags = getTagsBySession(deps.db, sessionId);
			const foundSet = new Set(allTags.map((tag) => tag.tagNumber));
			const unknownIds = allIds.filter((id) => !foundSet.has(id));
			if (unknownIds.length > 0) {
				return err(
					`Error: Unknown tag(s) ${formatIds(unknownIds)}. Check available tags in conversation.`,
				);
			}

			const activeTags = allTags.filter((tag) => tag.status === "active");
			const protectedTagIds = activeTags
				.map((tag) => tag.tagNumber)
				.sort((left, right) => right - left)
				.slice(0, deps.protectedTags);
			const protectedSet = new Set(protectedTagIds);

			const tagStatusMap = new Map(
				allTags.map((tag) => [tag.tagNumber, tag.status]),
			);

			const pendingOps = getPendingOps(deps.db, sessionId);
			const pendingMap = new Map(
				pendingOps.map((op) => [op.tagId, op.operation]),
			);

			// Reject drops on compaction-survivor tags. Mirrors OpenCode's
			// `tagStatusMap.get(id) === "compacted"` guard — those tags are
			// the synthesized survivors of an OpenCode compaction marker and