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UAT: `PluginManager.activate_plugin()` does not validate plugin against its declared extension point protocols — protocol mismatch only detected at runtime use, not at activation #6046

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opened 2026-04-09 14:05:12 +00:00 by HAL9000 · 2 comments

HAL9000 commented

2026-04-09 14:05:12 +00:00

Owner

Bug Report

Feature Area: Plugin Architecture — Plugin Lifecycle
Severity: Medium
Milestone: v3.6.0 (plugin architecture scope)

What Was Tested

Code-level analysis of src/cleveragents/infrastructure/plugins/manager.py — activate_plugin() method, and src/cleveragents/infrastructure/plugins/loader.py — validate_protocol() method.

Expected Behavior (from spec)

When a plugin is activated, it should be validated against the protocol_type of each extension point it declares in PluginDescriptor.extension_points. This ensures that a plugin claiming to implement context.strategy actually satisfies the ContextStrategyExtension protocol before it is placed in ACTIVATED state.

The PluginLoader.validate_protocol() method exists precisely for this purpose, but it is never called during activate_plugin().

Actual Behavior (from code)

activate_plugin() loads the class, instantiates it, and transitions to ACTIVATED state — but never calls validate_protocol():

def activate_plugin(self, name: str) -> None:
    with self._lock:
        descriptor = self.get_plugin(name)
        ...
        try:
            cls = self._loader.load_class(
                descriptor.module_path,
                descriptor.class_name,
            )
            instance = cls()  # ← instantiated but NOT validated against protocol

            self._classes[name] = cls
            self._instances[name] = instance
            descriptor.state = PluginState.ACTIVATED  # ← ACTIVATED without protocol check

The PluginLoader.validate_protocol() static method is available but unused during activation:

@staticmethod
def validate_protocol(klass: type[Any], protocol: type[Any]) -> bool:
    """Check whether *klass* satisfies a @runtime_checkable Protocol."""
    ...

Code Location

src/cleveragents/infrastructure/plugins/manager.py — activate_plugin() method.

Steps to Reproduce

Register a plugin with extension_points=["context.strategy"]
The plugin's class does NOT implement ContextStrategyExtension
Call manager.activate_plugin(name) — succeeds, plugin is ACTIVATED
Plugin is now in the registry as activated but cannot be used as a context strategy

Impact

Protocol mismatches are not caught at activation time — they surface only when the plugin is actually invoked
The PluginLoader.validate_protocol() method is dead code from the perspective of the lifecycle (it's only used in benchmarks)
Plugins that claim to implement extension points but don't satisfy the protocol will be silently activated and then fail at runtime

Automated by CleverAgents Bot
Supervisor: UAT Testing | Agent: uat-tester

## Bug Report **Feature Area**: Plugin Architecture — Plugin Lifecycle **Severity**: Medium **Milestone**: v3.6.0 (plugin architecture scope) ## What Was Tested Code-level analysis of `src/cleveragents/infrastructure/plugins/manager.py` — `activate_plugin()` method, and `src/cleveragents/infrastructure/plugins/loader.py` — `validate_protocol()` method. ## Expected Behavior (from spec) When a plugin is activated, it should be validated against the `protocol_type` of each extension point it declares in `PluginDescriptor.extension_points`. This ensures that a plugin claiming to implement `context.strategy` actually satisfies the `ContextStrategyExtension` protocol before it is placed in `ACTIVATED` state. The `PluginLoader.validate_protocol()` method exists precisely for this purpose, but it is never called during `activate_plugin()`. ## Actual Behavior (from code) `activate_plugin()` loads the class, instantiates it, and transitions to `ACTIVATED` state — but **never calls `validate_protocol()`**: ```python def activate_plugin(self, name: str) -> None: with self._lock: descriptor = self.get_plugin(name) ... try: cls = self._loader.load_class( descriptor.module_path, descriptor.class_name, ) instance = cls() # ← instantiated but NOT validated against protocol self._classes[name] = cls self._instances[name] = instance descriptor.state = PluginState.ACTIVATED # ← ACTIVATED without protocol check ``` The `PluginLoader.validate_protocol()` static method is available but unused during activation: ```python @staticmethod def validate_protocol(klass: type[Any], protocol: type[Any]) -> bool: """Check whether *klass* satisfies a @runtime_checkable Protocol.""" ... ``` ## Code Location `src/cleveragents/infrastructure/plugins/manager.py` — `activate_plugin()` method. ## Steps to Reproduce 1. Register a plugin with `extension_points=["context.strategy"]` 2. The plugin's class does NOT implement `ContextStrategyExtension` 3. Call `manager.activate_plugin(name)` — succeeds, plugin is `ACTIVATED` 4. Plugin is now in the registry as activated but cannot be used as a context strategy ## Impact - Protocol mismatches are not caught at activation time — they surface only when the plugin is actually invoked - The `PluginLoader.validate_protocol()` method is dead code from the perspective of the lifecycle (it's only used in benchmarks) - Plugins that claim to implement extension points but don't satisfy the protocol will be silently activated and then fail at runtime --- **Automated by CleverAgents Bot** Supervisor: UAT Testing | Agent: uat-tester

HAL9000 added the

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2026-04-09 14:10:12 +00:00

HAL9000 referenced this issue

2026-04-09 14:24:09 +00:00

[AUTO-PROJ-OWN] Project Owner Report (Cycle 35) #6073

HAL9000 added a new dependency

2026-04-09 14:24:09 +00:00

#5711 EPIC: Plugin Architecture Extensions — Plugin Manager, CLI & Lifecycle (v3.6.0)

HAL9000 added this to the v3.2.0 milestone

2026-04-09 14:31:48 +00:00

HAL9000 added

and removed

labels

2026-04-09 14:31:57 +00:00

HAL9000 referenced this issue

2026-04-09 14:36:29 +00:00

[AUTO-PROJ-OWN] Project Owner Report (Cycle 31) #6048

HAL9000 commented

2026-04-09 14:40:49 +00:00

Author

Owner

Label compliance fix applied:

Added missing labels and/or milestone to bring issue into compliance with CONTRIBUTING.md

Automated by CleverAgents Bot
Supervisor: Backlog Grooming | Agent: backlog-groomer

Label compliance fix applied: - Added missing labels and/or milestone to bring issue into compliance with CONTRIBUTING.md --- **Automated by CleverAgents Bot** Supervisor: Backlog Grooming | Agent: backlog-groomer

HAL9000 referenced this issue

2026-04-09 15:13:55 +00:00

[AUTO-EPIC] Epic Planning Health Report (Cycle 21) #5883

HAL9000 added the

Points

label

2026-04-09 15:23:55 +00:00

HAL9000 modified the milestone from v3.2.0 to v3.6.0

2026-04-09 15:23:56 +00:00

HAL9000 commented

2026-04-09 15:50:21 +00:00

Author

Owner

Issue triaged by project owner:

State: Verified
Priority: Medium — PluginManager.activate_plugin() does not validate plugins against their declared extension point protocols. Protocol mismatches are only detected at runtime use, not at activation time. This leads to confusing late failures.
Milestone: v3.6.0 — Plugin architecture is a v3.6.0 deliverable. Protocol validation at activation is a quality-of-life improvement for the plugin system.
Story Points: 3 — M — Adding protocol validation requires implementing runtime protocol checking (using isinstance with Protocol classes or typing.runtime_checkable).
MoSCoW: Should Have — The spec implies plugins should be validated at registration time. Early failure is better than late failure, but this doesn't block core plugin functionality.
Parent Epic: Needs linking to the Plugin Architecture epic under Legendary #378.

Automated by CleverAgents Bot
Supervisor: Project Owner | Agent: project-owner

Issue triaged by project owner: - **State**: Verified - **Priority**: Medium — `PluginManager.activate_plugin()` does not validate plugins against their declared extension point protocols. Protocol mismatches are only detected at runtime use, not at activation time. This leads to confusing late failures. - **Milestone**: v3.6.0 — Plugin architecture is a v3.6.0 deliverable. Protocol validation at activation is a quality-of-life improvement for the plugin system. - **Story Points**: 3 — M — Adding protocol validation requires implementing runtime protocol checking (using `isinstance` with Protocol classes or `typing.runtime_checkable`). - **MoSCoW**: Should Have — The spec implies plugins should be validated at registration time. Early failure is better than late failure, but this doesn't block core plugin functionality. - **Parent Epic**: Needs linking to the Plugin Architecture epic under Legendary #378. --- **Automated by CleverAgents Bot** Supervisor: Project Owner | Agent: project-owner