[aspiers]

Summary

• add the [Bugsnag] namespace to each message before handing it to the configured logger, so formatters that discard progname retain attribution
• preserve lazy logging, logger call arity, and the existing default output format
• keep prefixing idempotent, including space, colon, and exact-prefix forms
• cover the session delivery warning from Error Message: "Not delivering sessions due to an invalid api_key" needs to clarify it's coming from Bugsnag Gem #725 and update logger contract/integration coverage

Fixes #725

Testing

• affected specs: 236 examples, 0 failures
• logger and Rake integrations: 12 examples, 0 failures on Ruby 3.3.12
• RuboCop: lib/bugsnag/configuration.rb clean
• LSP diagnostics: 8 changed files, 0 errors
• broad non-integration suite: 694 passed; one unrelated metadata truncation threshold failure reproduces identically on the untouched base checkout under Ruby 3.3.12

[Copilot]

🟡 Changes recommended

It introduces an API/contract behavior change for logger progname handling and includes a small but concrete formatting bug for empty/nil messages that should be addressed before approval.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR aims to ensure Bugsnag attribution is preserved in log output by embedding the [Bugsnag] namespace directly into log messages (rather than relying on progname), and expands spec coverage around logging behavior and session-delivery warnings.

Changes:

• Prefix Bugsnag log messages with [Bugsnag] before passing them to the configured logger.
• Update default logger formatter to avoid duplicate [Bugsnag] prefixes (including : variants).
• Update/add specs to validate attribution behavior across multiple logging scenarios (on_error, breadcrumbs, sessions).

File summaries

File	Description
lib/bugsnag/configuration.rb	Prefixes log messages and adjusts default formatter to keep output attribution consistent/idempotent.
spec/session_tracker_spec.rb	Adds coverage asserting session-delivery invalid API key warnings include [Bugsnag].
spec/on_error_spec.rb	Updates expectations to assert [Bugsnag] appears in the emitted message (not via progname).
spec/integrations/logger_spec.rb	Updates expected API key warning format to match new prefixing style.
spec/configuration_spec.rb	Adjusts formatter expectations and adds coverage for default formatter idempotency.
spec/bugsnag_spec.rb	Updates expectations for internal notify error logging to include [Bugsnag] in message body.
spec/breadcrumbs/validator_spec.rb	Updates breadcrumb ignore logging to include [Bugsnag] attribution in message body.
spec/breadcrumbs/on_breadcrumb_callback_list_spec.rb	Updates callback error logging expectations to include [Bugsnag] in message body.

Review details

• Files reviewed: 8/8 changed files
• Comments generated: 2
• Review effort level: Lite

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[hannah-smartbear]

Hi @aspiers,

Thanks for taking the time to raise this PR!

Our engineers will take a look, and leave any comments or updates on this PR accordingly.