Root Cause

Summary

Normalized message utilities to operate on tinyagent dict messages (role + content[type]) only. Token estimation and resume sanitization no longer attempt to interpret legacy pydantic-ai message objects, aligning with the “full rip-out” direction.

Context

During the tun-1658 tinyagent migration, history is persisted as tinyagent dicts:

• assistant: {role: "assistant", content: [{type: "text"|"thinking"|"tool_call"|"image", ...}]}
• tool result: {role: "tool_result", tool_call_id: "...", content: [...]}

Older utilities still had defensive support for pydantic-ai style parts/part_kind shapes.

Root Cause

Utility modules (notably token counting and some sanitize logic) were written to accept polymorphic message inputs and silently “do something” for objects with .parts/.content. With tinyagent dict messages, this both (a) masked stale session formats and (b) caused unnecessary canonicalization overhead.

Changes

• src/tunacode/utils/messaging/token_counter.py
  • Now supports only tinyagent dict messages and CanonicalMessage.
  • Token estimation runs via to_canonical() + canonical parts, and counts tool-call metadata (tool_name, tool_call_id, args) heuristically.
• src/tunacode/core/agents/resume/sanitize.py
  • _is_request_message() is now role-based on dict messages (no canonical conversion).
  • Removed to_canonical dependency from sanitize (canonicalization remains in find_dangling_tool_calls() only).
• src/tunacode/utils/messaging/adapter.py
  • Refactored to_canonical() / from_canonical() into smaller helpers to satisfy ruff complexity constraints (no behavior change intended).
• Tests updated to use tinyagent message shapes:
  • tests/unit/utils/test_token_counter.py
  • tests/unit/test_sanitize_canonicalization.py

Behavioral Impact

• Token estimation now fails loudly if non-tinyagent message objects appear in history.
• Resume sanitization no longer performs redundant canonical conversions when scanning for consecutive request messages.
• No user-facing UI rendering changes yet (handled in Phase 7).

Related Cards

• [[tun-1658-phase5-cleanup]]