fix: resume BLOCKED tasks in preserved sandbox so Claude finds its session

When a task ran in a sandbox (/tmp/claudomator-sandbox-*) and went BLOCKED,
Claude stored its session under the sandbox path as the project slug. The
resume execution was running in project_dir, causing Claude to look for the
session in the wrong project directory and fail with "No conversation found".

Fix: carry SandboxDir through BlockedError → Execution → resume execution,
and run the resume in that directory so the session lookup succeeds.

- BlockedError gains SandboxDir field; claude.go sets it on BLOCKED exit
- storage.Execution gains SandboxDir (persisted via new sandbox_dir column)
- executor.go stores blockedErr.SandboxDir in the execution record
- server.go copies SandboxDir from latest execution to the resume execution
- claude.go uses e.SandboxDir as working dir for resume when set

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

1 files changed, 13 insertions, 4 deletions

diff --git a/internal/executor/claude.go b/internal/executor/claude.go
index 4839a90..0e29f7f 100644
--- a/internal/executor/claude.go
+++ b/internal/executor/claude.go
@@ -32,6 +32,7 @@ type ClaudeRunner struct {
 type BlockedError struct {
 	QuestionJSON string // raw JSON from the question file
 	SessionID    string // claude session to resume once the user answers
+	SandboxDir   string // preserved sandbox path; resume must run here so Claude finds its session files
 }
 
 func (e *BlockedError) Error() string { return fmt.Sprintf("task blocked: %s", e.QuestionJSON) }
@@ -98,10 +99,16 @@ func (r *ClaudeRunner) Run(ctx context.Context, t *task.Task, e *storage.Executi
 	}
 
 	// For new (non-resume) executions with a project_dir, clone into a sandbox.
-	// Resume executions run directly in project_dir to pick up the previous session.
+	// Resume executions run in the preserved sandbox (e.SandboxDir) so Claude
+	// finds its session files under the same project slug. If no sandbox was
+	// preserved (e.g. task had no project_dir), fall back to project_dir.
 	var sandboxDir string
 	effectiveWorkingDir := projectDir
-	if projectDir != "" && e.ResumeSessionID == "" {
+	if e.ResumeSessionID != "" {
+		if e.SandboxDir != "" {
+			effectiveWorkingDir = e.SandboxDir
+		}
+	} else if projectDir != "" {
 		var err error
 		sandboxDir, err = setupSandbox(projectDir)
 		if err != nil {
@@ -137,8 +144,10 @@ func (r *ClaudeRunner) Run(ctx context.Context, t *task.Task, e *storage.Executi
 	data, readErr := os.ReadFile(questionFile)
 	if readErr == nil {
 		os.Remove(questionFile) // consumed
-		// Preserve sandbox on BLOCKED — agent may have partial work.
-		return &BlockedError{QuestionJSON: strings.TrimSpace(string(data)), SessionID: e.SessionID}
+		// Preserve sandbox on BLOCKED — agent may have partial work and its
+		// Claude session files are stored under the sandbox's project slug.
+		// The resume execution must run in the same directory.
+		return &BlockedError{QuestionJSON: strings.TrimSpace(string(data)), SessionID: e.SessionID, SandboxDir: sandboxDir}
 	}
 
 	// Merge sandbox back to project_dir and clean up.