Implement unified plugin system from RFC #166

CLAUDE.md

@@ -107,6 +107,7 @@ with pointers to the deep-dive docs:
 - [dev-docs/teammates.md](dev-docs/teammates.md) - Teammates feature deep-dive
 - [dev-docs/message-hierarchy.md](dev-docs/message-hierarchy.md) - Fold/unfold state machine
 - [dev-docs/implementing-a-tool-renderer.md](dev-docs/implementing-a-tool-renderer.md) - How-to: add a new tool
+- [dev-docs/plugins.md](dev-docs/plugins.md) - Plugin system reference + author guide
 
 User-facing docs live in [docs/](docs/); plans and TODOs live in [work/](work/).
 

claude_code_log/factories/priorities.py

@@ -0,0 +1,46 @@
+"""Priority constants for plugin transformer ordering.
+
+Built-in factory detectors run in a fixed sequence; these constants
+expose their notional positions on a numeric priority scale so plugin
+transformers can declare where they sit relative to the built-ins
+without renumbering on every core change. Gaps of 100 leave room for
+plugin insertion.
+
+Convention (lower number = higher priority = runs first):
+
+- ``0`` through ``999``  — user/system entry classification
+- ``1000``               — generic text fallback (UserTextMessage)
+- ``5000`` through ``9999`` — tool input / output classification
+- ``10000`` and up       — never used by built-ins; reserved for plugin fallbacks
+
+See ``work/tool-renderer-plugins.md`` §Priority + ordering for the
+RFC discussion and worked examples.
+"""
+
+# User-entry detector chain (see factories/user_factory.py::create_user_message)
+COMMAND_MESSAGE: int = 100
+LOCAL_COMMAND_OUTPUT: int = 200
+BASH_INPUT_OUTPUT: int = 300
+TEAMMATE_MESSAGE: int = 400
+TASK_NOTIFICATION: int = 500
+HOOK_NOTIFICATION: int = 600  # PR #167's seat
+SLASH_COMMAND_ISMETA: int = 700
+TEXT_FALLBACK: int = 1000  # generic UserTextMessage
+
+# Tool-entry classification
+TOOL_INPUT_GENERIC: int = 5000
+TOOL_OUTPUT_GENERIC: int = 5100
+
+
+__all__ = [
+    "BASH_INPUT_OUTPUT",
+    "COMMAND_MESSAGE",
+    "HOOK_NOTIFICATION",
+    "LOCAL_COMMAND_OUTPUT",
+    "SLASH_COMMAND_ISMETA",
+    "TASK_NOTIFICATION",
+    "TEAMMATE_MESSAGE",
+    "TEXT_FALLBACK",
+    "TOOL_INPUT_GENERIC",
+    "TOOL_OUTPUT_GENERIC",
+]

claude_code_log/factories/tool_factory.py

@@ -18,6 +18,7 @@
 from pydantic import BaseModel
 
 from .agent_metadata_factory import parse_agent_result_metadata
+from ..plugins import apply_transformers
 from ..models import (
     # Tool input models
     AskUserQuestionInput,
@@ -1349,13 +1350,18 @@ def create_tool_use_message(
 
     # Create ToolUseMessage wrapper with parsed input for specialized formatting
     # Use ToolUseContent as fallback when no specialized parser exists
-    tool_use_message = ToolUseMessage(
+    tool_use_message: MessageContent = ToolUseMessage(
         meta,
         input=parsed if parsed is not None else tool_use,
         tool_use_id=tool_use.id,
         tool_name=tool_use.name,
     )
 
+    # Plugin transformer pass: lets a plugin rewrite the ToolUseMessage
+    # into a specialized subclass (e.g. ClmailCommunicateInputMessage)
+    # carrying its own format/title methods. No-op when no plugin matches.
+    tool_use_message = apply_transformers(tool_use_message, meta)
+
     return ToolItemResult(
         message_type="tool_use",
         content=tool_use_message,
@@ -1401,7 +1407,7 @@ def create_tool_result_message(
     )
 
     # Create content model with rendering context
-    content_model = ToolResultMessage(
+    content_model: MessageContent = ToolResultMessage(
         meta,
         tool_use_id=tool_result.tool_use_id,
         output=parsed_output,
@@ -1410,6 +1416,10 @@ def create_tool_result_message(
         file_path=result_file_path,
     )
 
+    # Plugin transformer pass: lets a plugin rewrite the ToolResultMessage
+    # into a specialized subclass with its own format/title methods.
+    content_model = apply_transformers(content_model, meta)
+
     return ToolItemResult(
         message_type="tool_result",
         content=content_model,

claude_code_log/factories/user_factory.py

@@ -42,6 +42,7 @@
     UserSlashCommandMessage,
     UserTextMessage,
 )
+from ..plugins import apply_transformers
 from .task_notification_factory import (
     create_task_notification_message,
     has_task_notification,
@@ -467,6 +468,30 @@ def create_user_message(
     content_list: list[ContentItem],
     text_content: str,
     is_slash_command: bool = False,
+) -> Optional[UserMessageContent]:
+    """Wrapper: build the candidate, then run plugin transformers.
+
+    The body lives in :func:`_classify_user_message`; this wrapper
+    applies the plugin transformer pass to the result so every
+    classification path (slash-command, bash, teammate, ...) becomes
+    rewriteable by a plugin, not just the generic-text fallback.
+    Transformers whose ``applies_to`` doesn't subclass-match the
+    candidate's type pass through with no-op cost.
+    """
+    candidate = _classify_user_message(
+        meta, content_list, text_content, is_slash_command
+    )
+    if candidate is None:
+        return None
+    transformed = apply_transformers(candidate, meta)
+    return cast("UserMessageContent", transformed)
+
+
+def _classify_user_message(
+    meta: MessageMeta,
+    content_list: list[ContentItem],
+    text_content: str,
+    is_slash_command: bool = False,
 ) -> Optional[UserMessageContent]:
     """Create a user message content model from content items.
 

claude_code_log/html/renderer.py

@@ -264,6 +264,14 @@ def _to_posix(s: str) -> str:
 class HtmlRenderer(Renderer):
     """HTML renderer for Claude Code transcripts."""
 
+    # Consulted by Renderer._dispatch_format Strategy 2: plugin-defined
+    # content classes contributing a ``format_html`` method get picked up
+    # here. See work/tool-renderer-plugins.md §`_dispatch_format`
+    # resolution order. Class-side ``format_html`` may return None to
+    # opt for mistune-derived HTML; that fallback is handled by callers
+    # of format_content, not by the dispatcher itself.
+    _class_dispatch_format: str = "html"
+
     def __init__(self, image_export_mode: str = "embedded"):
         """Initialize the HTML renderer.