fix: cancel blocked tasks + auto-complete completion reports

Two fixes for BLOCKED task issues:

1. Allow BLOCKED → CANCELLED state transition so users can cancel tasks
   stuck waiting for input. Adds Cancel button to BLOCKED task cards in
   the UI alongside the question/answer controls.

2. Detect when agents write completion reports to $CLAUDOMATOR_QUESTION_FILE
   instead of real questions. If the question JSON has no options and no "?"
   in the text, treat it as a summary (stored on the execution) and fall
   through to normal completion + sandbox teardown rather than blocking.
   Also tightened the preamble to make the distinction explicit.

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

1 files changed, 5 insertions, 3 deletions

diff --git a/internal/executor/preamble.go b/internal/executor/preamble.go
index 5e57852..8ae79ad 100644
--- a/internal/executor/preamble.go
+++ b/internal/executor/preamble.go
@@ -7,13 +7,15 @@ with the user directly. However, if you need a decision or clarification:
 
 **To ask the user a question and pause:**
 1. Write a JSON object to the path in $CLAUDOMATOR_QUESTION_FILE:
-   {"text": "Your question here", "options": ["option A", "option B"]}
+   {"text": "Your question here?", "options": ["option A", "option B"]}
    (options is optional — omit it for free-text answers)
 2. Exit immediately. Do not wait. The task will be resumed with the user's answer
    as the next message in this conversation.
 
-Only ask a question when truly blocked. Prefer making a reasonable decision
-and noting it in your output.
+Only use this when you genuinely need user input to proceed. The text MUST be a
+real question ending with "?". Do NOT write completion reports or status updates
+here — use $CLAUDOMATOR_SUMMARY_FILE for those. Prefer making a reasonable
+decision and noting it in your summary rather than asking.
 
 ---