Summary

• Add connection error patterns (ECONNREFUSED, ECONNRESET, socket hang up, fetch failed, APIConnectionError, etc.) to ERROR_PATTERNS
• Wire isConnectionErrorMessage() into classifyFailoverReason() as "timeout" (retryable), so the failover mechanism can retry on a different provider
• Return a friendly user-facing message instead of leaking raw error text to channels

Test plan

• New isConnectionErrorMessage test suite (3 tests: SDK message, common patterns, negative cases)
• New formatAssistantErrorText tests for connection error messages (2 tests)
• All 269 existing tests pass
• pnpm build && pnpm check clean

Fixes #15083

lobster-biscuit

🤖 Generated with Claude Code

Greptile Overview

Greptile Summary

This change adds a new connection bucket to the agent error pattern matcher, exposes it via isConnectionErrorMessage(), and uses it in two places:

• formatAssistantErrorText() now rewrites connection-related failures (e.g., ECONNREFUSED, ECONNRESET, socket hang up, fetch failed, APIConnectionError) into a stable, user-friendly message.
• classifyFailoverReason() treats those connection errors as retryable transport failures by mapping them to the existing "timeout" failover reason.

New Vitest suites cover both the message classifier and the formatting behavior.

Confidence Score: 5/5

• This PR is safe to merge with minimal risk.
• Changes are localized to error classification/formatting, are covered by new unit tests, and preserve existing failover reason types by mapping connection errors to the already-supported "timeout" category.
• No files require special attention

_{Last reviewed commit: 932a781}

_{(4/5) You can add custom instructions or style guidelines for the agent here!}