Align Chronicle session store schema with actual stored data

[jeffreybulanadi]

Fixes #313640.

Two divergences between the documented schema and stored data:

1. Truncation marker

The schema description stated truncated content ends with the unicode ellipsis (U+2026 ...), but truncateForStore appended three ASCII periods (...). This caused queries like assistant_response LIKE '%...' to return 0 rows while LIKE '%...' returned 36 - the opposite of what the documentation implied.

Change the ellipsis constant from '...' to the single unicode character so the stored marker matches the documented value. A secondary benefit: the suffix shrinks from 3 code units to 1, freeing 2 more characters of content per truncated value without exceeding maxLength.

2. session_files tool_name scope

read_file, list_dir, and view_image were included in FILE_TRACKING_TOOLS, so every file the agent read was inserted into session_files. In practice read_file alone accounted for 90% of rows (165 out of ~183). The intent of session_files is to record files the agent wrote, not every file it inspected.

Remove those three read-only tools from FILE_TRACKING_TOOLS. Only write operations (replace_string_in_file, insert_edit_into_file, create_file, edit_notebook_file, apply_patch, str_replace_editor, create, create_directory, multi_replace_string_in_file) now populate session_files.

Update the schema description in chronicleIntent.ts and the JSDoc on FILE_TRACKING_TOOLS to match.

Tests

• read_file and list_dir cases updated to assert undefined (not tracked).
• view_image added to the read-only/unknown assertion group.
• Length-based truncation tests in sessionReindexer.spec.ts are unaffected because they only check .length <= max, not the specific suffix character.

[Copilot]

Pull request overview

Aligns Chronicle’s documented session-store schema with what is actually persisted, focusing on truncation markers and the intended semantics of session_files (write-tracking vs read-tracking).

Changes:

• Switch truncation marker used by truncateForStore from ASCII ... to Unicode ellipsis ….
• Limit session_files population to write tools only by removing read-only tools (read_file, list_dir, view_image) from FILE_TRACKING_TOOLS.
• Update the Chronicle schema description and adjust extractFilePath unit tests to reflect the new write-only tracking behavior.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
extensions/copilot/src/extension/intents/node/chronicleIntent.ts	Updates the schema description strings to match the new truncation marker and write-only session_files semantics.
extensions/copilot/src/extension/chronicle/common/test/sessionStoreTracking.spec.ts	Updates tests to assert read-only tools are not tracked in session_files, and adds view_image to the non-tracked group.
extensions/copilot/src/extension/chronicle/common/sessionStoreTracking.ts	Implements the Unicode ellipsis truncation marker and restricts file tracking to write tools only.

Comments suppressed due to low confidence (3)

extensions/copilot/src/extension/chronicle/common/sessionStoreTracking.ts:70

• After dropping list_dir from FILE_TRACKING_TOOLS, the inline comment in extractFilePath still says “list_dir uses 'path'”. Please update that comment so it no longer references tools that are intentionally not tracked, to avoid future confusion while maintaining/expanding tool tracking.

/** Tools whose arguments contain a file path being written (created or modified). */
const FILE_TRACKING_TOOLS = new Set([
	// VS Code model-facing tool names (from ToolName enum)
	'replace_string_in_file',
	'multi_replace_string_in_file',

extensions/copilot/src/extension/chronicle/common/sessionStoreTracking.ts:41

• truncateForStore now uses the Unicode ellipsis (…) as the truncation marker, but there’s no unit test asserting the exact suffix (only length-based assertions elsewhere). Adding a small test here would prevent regressions back to '...' and ensure the documented schema marker stays aligned with stored data.

/**
 * Truncate a string to at most `maxLength` stored characters, appending '…' if truncated.
 * The returned value, including the truncation suffix, never exceeds `maxLength`.
 * Returns `undefined` for falsy input.
 */
export function truncateForStore(value: string | undefined, maxLength: number): string | undefined {
	if (!value) {
		return undefined;
	}
	if (value.length <= maxLength) {
		return value;
	}
	const ellipsis = '…';
	if (maxLength <= ellipsis.length) {
		return ellipsis.slice(0, maxLength);
	}
	return value.slice(0, maxLength - ellipsis.length).trimEnd() + ellipsis;

extensions/copilot/src/extension/chronicle/common/sessionStoreTracking.ts:70

• Removing read_file/list_dir/view_image from FILE_TRACKING_TOOLS will change extractFilePath() behavior and currently breaks existing tests that still expect read-only tools to populate session_files (e.g. extensions/copilot/src/extension/chronicle/node/test/sessionReindexer.spec.ts and .../common/test/standupPrompt.spec.ts). Update those tests/fixtures to only assert tracking for write tools (e.g. create_file, apply_patch, etc.).

/** Tools whose arguments contain a file path being written (created or modified). */
const FILE_TRACKING_TOOLS = new Set([
	// VS Code model-facing tool names (from ToolName enum)
	'replace_string_in_file',
	'multi_replace_string_in_file',