Summary

• Problem: extractTextFromChatContent returned raw JSON strings like [{"type":"output_text","text":"..."}] instead of extracting the text, because it didn't detect JSON-stringified content block arrays and didn't recognize "output_text" blocks from the OpenAI Responses API.
• Why it matters: Heartbeat replies were delivered to Discord as unreadable JSON walls; recursive serialization amplified this into exponentially growing backslash escaping.
• What changed: Added isTextBlockType() (accepts both "text" and "output_text"), tryParseStringifiedContentBlocks() (detects and extracts text from stringified arrays), and 14 new tests.
• What did NOT change (scope boundary): No changes to the heartbeat runner, agent runner, session storage, or delivery pipeline — the fix is isolated to the shared text extraction utility.

Change Type (select all)

• Bug fix
• Feature
• Refactor
• Docs
• Security hardening
• Chore/infra

Scope (select all touched areas)

• Gateway / orchestration
• Skills / tool execution
• Auth / tokens
• Memory / storage
• Integrations
• API / contracts
• UI / DX
• CI/CD / infra

Linked Issue/PR

• Closes [Bug]: Heartbeat responses serialized as raw JSON in Discord delivery — recursive escaping / slash loop #29028

User-visible / Behavior Changes

• Heartbeat responses using OpenAI Responses API models are now delivered as plain text instead of raw JSON content block arrays.
• Recursive escaping / slash loops in heartbeat messages are eliminated.

Security Impact (required)

• New permissions/capabilities? No
• Secrets/tokens handling changed? No
• New/changed network calls? No
• Command/tool execution surface changed? No
• Data access scope changed? No

Repro + Verification

Environment

• OS: Ubuntu 24.04 (reporter), macOS (dev)
• Runtime/container: Node 22+
• Model/provider: OpenAI Responses API (any model)
• Integration/channel: Discord (heartbeat delivery)
• Relevant config: Heartbeat enabled with OpenAI Responses API model

Steps

1. Configure a heartbeat with an OpenAI Responses API model
2. Wait for heartbeat to trigger and generate a response
3. Observe the delivered message in Discord

Expected

• Plain text heartbeat message (e.g. "Everything looks good")

Actual

• Raw JSON: [{"type":"output_text","text":"Everything looks good"}]
• In severe cases: recursive escaping with walls of \ characters

Evidence

• Failing test/log before + passing after — 14 new tests covering stringified content arrays, output_text blocks, mixed types, sanitizer pass-through, recursive escaping, and edge cases. All 28 tests pass.
• Trace/log snippets
• Screenshot/recording
• Perf numbers (if relevant)

Human Verification (required)

• Verified scenarios: All 28 unit tests pass including 14 new tests for the fix
• Edge cases checked: plain strings starting with [, JSON arrays of non-objects, arrays missing type field, whitespace-only text blocks, doubly-stringified content, sanitizer applied to stringified blocks
• What you did not verify: Live heartbeat delivery to Discord with a real OpenAI Responses API model

Compatibility / Migration

• Backward compatible? Yes
• Config/env changes? No
• Migration needed? No

Failure Recovery (if this breaks)

• How to disable/revert this change quickly: Revert the single commit on src/shared/chat-content.ts
• Files/config to restore: src/shared/chat-content.ts
• Known bad symptoms reviewers should watch for: Regular plain-text strings being incorrectly parsed as content block arrays (mitigated by requiring every array element to have a type field)

Risks and Mitigations

• Risk: A plain string that happens to be valid JSON matching the content block shape could be incorrectly parsed.
  • Mitigation: Strict validation requires every element to be an object with a type field — this pattern is extremely unlikely in natural text. The function returns the extracted text either way, so the worst case is equivalent output.