feat(executor): introduce AgentChannel seam for runner signals

Defines AgentChannel — the normalized interface by which a runner reports
agent-originated signals (AskUser, ReportSummary, SpawnSubtask,
RecordProgress) — plus a default storeChannel implementation backed by
storage. Runner.Run now takes an AgentChannel; the pool constructs one
per execution.

The file transport routes its post-exit summary detection through
ch.ReportSummary (buffered onto the execution so the pool still applies
its extract/synthesize fallbacks, no double-write). AskUser returns
ErrAgentBlocked since write-and-exit cannot answer in-session; question
persistence stays with the pool's BlockedError handling. SpawnSubtask
and RecordProgress are implemented and tested, ready for the MCP
transport in Phase 2 where the channel becomes fully load-bearing.

Store gains CreateEvent so the channel can emit agent_message events.

https://claude.ai/code/session_01SESwn7kQ7oP62trWw6pc39

1 files changed, 5 insertions, 3 deletions

diff --git a/internal/executor/executor_test.go b/internal/executor/executor_test.go
index 9214872..d98efbf 100644
--- a/internal/executor/executor_test.go
+++ b/internal/executor/executor_test.go
@@ -12,6 +12,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/thepeterstone/claudomator/internal/event"
 	"github.com/thepeterstone/claudomator/internal/storage"
 	"github.com/thepeterstone/claudomator/internal/task"
 )
@@ -63,7 +64,7 @@ type mockRunner struct {
 	onRun    func(*task.Task, *storage.Execution) error
 }
 
-func (m *mockRunner) Run(ctx context.Context, t *task.Task, e *storage.Execution) error {
+func (m *mockRunner) Run(ctx context.Context, t *task.Task, e *storage.Execution, _ AgentChannel) error {
 	m.mu.Lock()
 	m.calls++
 	cb := m.onRun
@@ -391,11 +392,11 @@ func (m *logPatherMockRunner) ExecLogDir(execID string) string {
 	return filepath.Join(m.logDir, execID)
 }
 
-func (m *logPatherMockRunner) Run(ctx context.Context, t *task.Task, e *storage.Execution) error {
+func (m *logPatherMockRunner) Run(ctx context.Context, t *task.Task, e *storage.Execution, ch AgentChannel) error {
 	m.mu.Lock()
 	m.capturedPath = e.StdoutPath
 	m.mu.Unlock()
-	return m.mockRunner.Run(ctx, t, e)
+	return m.mockRunner.Run(ctx, t, e, ch)
 }
 
 // TestPool_Execute_LogPathsPreSetBeforeRun verifies that when the runner
@@ -1194,6 +1195,7 @@ func (m *minimalMockStore) GetStory(_ string) (*task.Story, error)
 func (m *minimalMockStore) ListTasksByStory(_ string) ([]*task.Task, error)     { return nil, nil }
 func (m *minimalMockStore) UpdateStoryStatus(_ string, _ task.StoryState) error { return nil }
 func (m *minimalMockStore) CreateTask(_ *task.Task) error                      { return nil }
+func (m *minimalMockStore) CreateEvent(_ *event.Event) error                   { return nil }
 func (m *minimalMockStore) UpdateTaskCheckerReport(_ string, _ string) error   { return nil }
 func (m *minimalMockStore) GetCheckerTask(_ string) (*task.Task, error)        { return nil, nil }