executor: persist log paths at execution create time, not just at end

Add LogPather interface; ClaudeRunner implements it via ExecLogDir().
Pool pre-populates stdout_path/stderr_path/artifact_dir on the execution
record before CreateExecution, so paths are in the DB from the moment
a task starts running.

ClaudeRunner.Run() skips path assignment when already set by the pool.

Also update scripts/debug-execution to derive paths from the known
convention (<data-dir>/executions/<exec-id>/) as a fallback for
historical records that predate this change.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/internal/executor/executor.go b/internal/executor/executor.go
index 51f468e..eb23c02 100644
--- a/internal/executor/executor.go
+++ b/internal/executor/executor.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"log/slog"
+	"path/filepath"
 	"sync"
 	"time"
 
@@ -12,6 +13,13 @@ import (
 	"github.com/google/uuid"
 )
 
+// LogPather is an optional interface runners can implement to provide the log
+// directory for an execution before it starts. The pool uses this to persist
+// log paths at CreateExecution time rather than waiting until execution ends.
+type LogPather interface {
+	ExecLogDir(execID string) string
+}
+
 // Runner executes a single task and returns the result.
 type Runner interface {
 	Run(ctx context.Context, t *task.Task, exec *storage.Execution) error
@@ -115,6 +123,16 @@ func (p *Pool) execute(ctx context.Context, t *task.Task) {
 		Status:    "RUNNING",
 	}
 
+	// Pre-populate log paths so they're available in the DB immediately —
+	// before the subprocess starts — enabling live tailing and debugging.
+	if lp, ok := p.runner.(LogPather); ok {
+		if logDir := lp.ExecLogDir(execID); logDir != "" {
+			exec.StdoutPath = filepath.Join(logDir, "stdout.log")
+			exec.StderrPath = filepath.Join(logDir, "stderr.log")
+			exec.ArtifactDir = logDir
+		}
+	}
+
 	// Record execution start.
 	if err := p.store.CreateExecution(exec); err != nil {
 		p.logger.Error("failed to create execution record", "error", err)