/**
 * Core Chi Commons types.
 *
 * A "source" is one discoverable unit of historical context for the current
 * project: a raw Pi session or a reduced artifact. Artifacts remain ordinary
 * Pi v3 JSONL sessions with custom reduction-metadata entries; reducer
 * metadata is the source of truth for lineage and titles.
 *
 * z is the zoom/reduction level (python-style tree depth indexing, see
 * DESIGN.md): z >= 0 is leaf-relative (z=0 raw records, z=1 adjacent pairs),
 * z < 0 is root-relative (z=-1 the single root record).
 */

export type ZLevel = -1 | 0 | 1;

/** Lineage carried by reduced artifacts; every field survives reload. */
export interface SourceLineage {
	sourceRepo?: string;
	sourceSessionIds: string[];
	sourceEntryIds: string[];
	reducerVersion?: string;
	promptVersion?: string;
	model?: string;
	/** Content hash / reduction key from the reducer or planner. */
	contentHash?: string;
}

/** One discoverable Commons source for the current project. */
export interface CommonsSource {
	/** Session UUID from the JSONL header. */
	id: string;
	/** Absolute path of the JSONL file. */
	path: string;
	z: ZLevel;
	/** Source title: session name, reducer title, or pre-reduction first-request fallback. */
	title: string;
	/** ISO timestamp of the most recent entry (recency ordering key). */
	timestamp: string;
	/** Number of tree entries in the file (excluding the header). */
	entryCount: number;
	/**
	 * Rough token estimate (~4 chars/token) of the model-visible content:
	 * text, thinking, and tool-call arguments — what replaying the session
	 * costs in context, approximating the statusline count (minus system
	 * prompt and tool schemas, which belong to the resuming runtime).
	 */
	approxTokens: number;
	/** Present for reduced (z != 0) artifacts. */
	lineage?: SourceLineage;
}