RFC: allow users to pass a custom logger to init

[dwwoelfel]

This is an attempt to address #2742 without making the logs harder to read in the devtools console.

Users can pass a custom logger where they format things however they like. If you wanted to JSON stringify, you might do:

const db = init({
  ...config,
  schema,
  verbose: true,
  logger: {
    debug: (...args) => console.debug(JSON.stringify(args)),
    info: (...args) => console.info(JSON.stringify(args)),
    error: (...args) => console.error(JSON.stringify(args)),
  },
});

Or if you just wanted to json.stringify objects, you could do:

const db = init({
  ...config,
  schema,
  verbose: true,
  logger: {
    debug: (...args) =>
      console.debug(
        ...args.map((a) => (typeof a === 'object' ? JSON.stringify(a) : a)),
      ),
    info: (...args) =>
      console.info(
        ...args.map((a) => (typeof a === 'object' ? JSON.stringify(a) : a)),
      ),
    error: (...args) =>
      console.error(
        ...args.map((a) => (typeof a === 'object' ? JSON.stringify(a) : a)),
      ),
  },
});

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Reviewing files that changed from the base of the PR and between 0afe605 and 66be1fb.

📒 Files selected for processing (1)

• client/packages/version/src/version.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• client/packages/version/src/version.ts

---

📝 Walkthrough

Walkthrough

Adds an injectable Logger across client packages: core logging accepts a baseLogger, Config/InstantConfig types gain an optional logger field, Reactor and admin database wire the injected logger, framework packages re-export the Logger type, and the package version is bumped.

Changes

Custom Logger Injection

Layer / File(s)	Summary
Core logger function enhancement client/packages/core/src/utils/log.ts	createLogger now accepts an optional baseLogger parameter (defaulting to console) and routes info, debug, and error calls to that logger instead of hard-coded console references.
Core configuration types client/packages/core/src/index.ts	Config and InstantConfig types are extended with optional logger?: Logger field, and Logger type is imported and exported from core's public API.
Reactor logger integration client/packages/core/src/Reactor.js	Reactor constructor passes config.logger to createLogger, enabling the injected logger in core reactor initialization.
Admin package implementation client/packages/admin/src/index.ts	Admin package imports Logger, adds optional logger to Config/InstantConfig, replaces the local logger factory with the core-compatible createLogger(isEnabled, baseLogger), wires config.logger into InstantAdminDatabase, and re-exports Logger.
Framework package type exports client/packages/react/src/index.ts, client/packages/react-native/src/index.ts, client/packages/solidjs/src/index.ts, client/packages/svelte/src/lib/index.ts, client/packages/vue/src/index.ts	Each framework package imports and re-exports the Logger type from core to expose it in their public type surfaces.
Version bump client/packages/version/src/version.ts	Package version updated from v1.0.44 to v1.0.45.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• instantdb/instant#2537: Overlaps changes to admin config/logging initialization surface where verbose and logger wiring interact.

Suggested reviewers

• stopachka
• nezaj

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: allowing users to pass a custom logger to the init function, which aligns with all modifications across the codebase.
Description check	✅ Passed	The description clearly explains the feature's purpose, provides concrete usage examples, and addresses the referenced issue, directly relating to the changeset.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch custom-logger

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[github-actions]

View Vercel preview at instant-www-js-custom-logger-jsv.vercel.app.

[coderabbitai]

🧹 Nitpick comments (1)

client/packages/admin/src/index.ts (1)

1107-1116: ⚡ Quick win

Consider importing createLogger from core to reduce duplication.

The admin package defines its own createLogger helper, but the core package already exports a similar function (see client/packages/core/src/utils/log.ts). The core version includes a getStats parameter for appending diagnostic info to logs, which the admin version omits.

If the admin package doesn't need stats, you could:

1. Import the core createLogger and pass a no-op getStats: () => ({}), or
2. Propose making getStats optional in the core version with a default no-op

This would eliminate duplication and ensure consistent logger behavior across packages.

♻️ Example: Import from core

+import createLogger from '`@instantdb/core/src/utils/log`';
+
 class InstantAdminDatabase<...> {
   ...
   constructor(_config: Config) {
     ...
-    this.#log = createLogger(!!this.config.verbose, this.config.logger);
+    this.#log = createLogger(
+      !!this.config.verbose,
+      () => ({}),  // no-op getStats
+      this.config.logger,
+    );
   }
 }
-
-function createLogger(
-  isEnabled: boolean,
-  baseLogger: Logger = console,
-): Logger {
-  return {
-    info: isEnabled ? (...args: any[]) => baseLogger.info(...args) : () => {},
-    debug: isEnabled ? (...args: any[]) => baseLogger.debug(...args) : () => {},
-    error: isEnabled ? (...args: any[]) => baseLogger.error(...args) : () => {},
-  };
-}

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@client/packages/admin/src/index.ts` around lines 1107 - 1116, The admin
package redefines createLogger, duplicating logic from core's createLogger (see
client/packages/core/src/utils/log.ts) which accepts an additional getStats
parameter; fix by removing the local createLogger and importing the core
createLogger into client/packages/admin/src/index.ts, calling it with the same
isEnabled and baseLogger arguments and supplying a no-op getStats (() => ({}))
if admin doesn't need stats — alternatively, change the core createLogger
signature to make getStats optional with a default no-op so admin can import and
call it unchanged.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@client/packages/admin/src/index.ts`:
- Around line 1107-1116: The admin package redefines createLogger, duplicating
logic from core's createLogger (see client/packages/core/src/utils/log.ts) which
accepts an additional getStats parameter; fix by removing the local createLogger
and importing the core createLogger into client/packages/admin/src/index.ts,
calling it with the same isEnabled and baseLogger arguments and supplying a
no-op getStats (() => ({})) if admin doesn't need stats — alternatively, change
the core createLogger signature to make getStats optional with a default no-op
so admin can import and call it unchanged.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 0ce2225d-e475-4fa7-ab8d-70c53f6fc755

📥 Commits

Reviewing files that changed from the base of the PR and between 6d97f6d and 50f9652.

📒 Files selected for processing (9)

• client/packages/admin/src/index.ts
• client/packages/core/src/Reactor.js
• client/packages/core/src/index.ts
• client/packages/core/src/utils/log.ts
• client/packages/react-native/src/index.ts
• client/packages/react/src/index.ts
• client/packages/solidjs/src/index.ts
• client/packages/svelte/src/lib/index.ts
• client/packages/vue/src/index.ts

[nezaj]

LGTM!