refactor(telemetry): pull settings into src/settings, simplify sink and tests

Move readTelemetryLevel and readLocalJsonlConfig (with the setting
key constants and defaults) into src/settings/telemetry.ts, matching
the existing notifications and cli settings pattern. Both functions
take a WorkspaceConfiguration argument so they are easy to test.

LocalJsonlSink keeps its static start() factory but the constructor
is now side-effect-free: it just assigns fields. start() is the
single place that reads the config, subscribes the watcher, schedules
the flush timer, and kicks off cleanup. The class implements
vscode.Disposable explicitly.

Tighten comments on the sink and on cleanupFiles. Inline #fileName
into #doFlush since it had only one caller.

Tests: per-test setup() harness instead of beforeEach-installed
helpers. Module-level state is gone, all setup happens inside each
test through setup(), and afterEach disposes any active sinks. The
"warns once" log-side-effect assertion is dropped from the buffer
overflow test (the file content already proves the behavior).
fileCleanup tests use path.basename instead of split("/") for
cross-platform safety.

Author: EhabY

src/settings/telemetry.ts

@@ -0,0 +1,69 @@
+import type { WorkspaceConfiguration } from "vscode";
+
+import type { TelemetryLevel } from "../telemetry/event";
+
+export const TELEMETRY_LEVEL_SETTING = "coder.telemetry.level";
+export const LOCAL_JSONL_SETTING = "coder.telemetry.localJsonl";
+
+/** Telemetry level. Falls back to `local` for any invalid value. */
+export function readTelemetryLevel(
+	cfg: Pick<WorkspaceConfiguration, "get">,
+): TelemetryLevel {
+	const value = cfg.get<string>(TELEMETRY_LEVEL_SETTING);
+	return value === "off" || value === "local" ? value : "local";
+}
+
+export interface LocalJsonlConfig {
+	flushIntervalMs: number;
+	flushBatchSize: number;
+	bufferLimit: number;
+	maxFileBytes: number;
+	maxAgeDays: number;
+	maxTotalBytes: number;
+}
+
+export const LOCAL_JSONL_DEFAULTS: LocalJsonlConfig = {
+	flushIntervalMs: 15_000,
+	flushBatchSize: 100,
+	bufferLimit: 500,
+	maxFileBytes: 5 * 1024 * 1024,
+	maxAgeDays: 30,
+	maxTotalBytes: 100 * 1024 * 1024,
+};
+
+/** Reads the local JSONL sink config, defaulting any missing or invalid
+ *  field. Each field must be a positive number to override the default. */
+export function readLocalJsonlConfig(
+	cfg: Pick<WorkspaceConfiguration, "get">,
+): LocalJsonlConfig {
+	const raw = cfg.get(LOCAL_JSONL_SETTING);
+	const obj =
+		raw && typeof raw === "object" ? (raw as Record<string, unknown>) : {};
+	return {
+		flushIntervalMs: positiveNumber(
+			obj.flushIntervalMs,
+			LOCAL_JSONL_DEFAULTS.flushIntervalMs,
+		),
+		flushBatchSize: positiveNumber(
+			obj.flushBatchSize,
+			LOCAL_JSONL_DEFAULTS.flushBatchSize,
+		),
+		bufferLimit: positiveNumber(
+			obj.bufferLimit,
+			LOCAL_JSONL_DEFAULTS.bufferLimit,
+		),
+		maxFileBytes: positiveNumber(
+			obj.maxFileBytes,
+			LOCAL_JSONL_DEFAULTS.maxFileBytes,
+		),
+		maxAgeDays: positiveNumber(obj.maxAgeDays, LOCAL_JSONL_DEFAULTS.maxAgeDays),
+		maxTotalBytes: positiveNumber(
+			obj.maxTotalBytes,
+			LOCAL_JSONL_DEFAULTS.maxTotalBytes,
+		),
+	};
+}
+
+function positiveNumber(value: unknown, fallback: number): number {
+	return typeof value === "number" && value > 0 ? value : fallback;
+}

src/telemetry/service.ts

@@ -2,6 +2,10 @@ import * as vscode from "vscode";
 
 import { watchConfigurationChanges } from "../configWatcher";
 import { type Logger } from "../logging/logger";
+import {
+	TELEMETRY_LEVEL_SETTING,
+	readTelemetryLevel,
+} from "../settings/telemetry";
 
 import {
 	buildSession,
@@ -15,13 +19,14 @@ import {
 } from "./event";
 import { NOOP_SPAN, type Span } from "./span";
 
-const TELEMETRY_LEVEL_SETTING = "coder.telemetry.level";
-
 const LEVEL_ORDER: Readonly<Record<TelemetryLevel, number>> = {
 	off: 0,
 	local: 1,
 };
 
+const readLevel = (): TelemetryLevel =>
+	readTelemetryLevel(vscode.workspace.getConfiguration());
+
 /** Trace context shared by all events in one trace. */
 interface SpanOptions {
 	traceId: string;
@@ -280,13 +285,3 @@ export class TelemetryService implements vscode.Disposable {
 	}
 }
 
-function readLevel(): TelemetryLevel {
-	const value = vscode.workspace
-		.getConfiguration()
-		.get<string>(TELEMETRY_LEVEL_SETTING);
-	return isTelemetryLevel(value) ? value : "local";
-}
-
-function isTelemetryLevel(value: unknown): value is TelemetryLevel {
-	return value === "off" || value === "local";
-}