Towers of Hanoi Demo

A durability proof demonstrating Gas Town’s ability to execute arbitrarily long sequential workflows with crash recovery and session cycling.

What This Proves

1. Large Molecule Creation: Creating 1000+ issues in a single workflow
2. Sequential Execution: Dependencies chain properly across many steps
3. Crash Recovery: Work resumes correctly after session restart
4. Nondeterministic Idempotence: Different sessions, same outcome

The Math

Towers of Hanoi requires 2^n - 1 moves for n disks:

Disks	Moves	Formula Size	Est. Runtime
7	127	~19 KB	~14 sec
9	511	~74 KB	~1 min
10	1,023	~149 KB	~2 min
15	32,767	~4.7 MB	~1 hour
20	1M+	~163 MB	~30 hours

Pre-Generated Formulas

Located in .beads/formulas/:

• towers-of-hanoi-7.formula.toml - 127 moves (quick test)
• towers-of-hanoi-9.formula.toml - 511 moves (medium test)
• towers-of-hanoi-10.formula.toml - 1023 moves (standard demo)

Running the Demo

Quick Test (7 disks, ~14 seconds)

# Create wisp
bd mol wisp towers-of-hanoi-7 --json | jq -r '.new_epic_id'
# Returns: gt-eph-xxx

# Get all child IDs
bd list --parent=gt-eph-xxx --limit=200 --json | jq -r '.[].id' > /tmp/ids.txt

# Close all issues (serial)
while read id; do bd --no-daemon close "$id" >/dev/null; done < /tmp/ids.txt

# Burn the wisp (cleanup)
bd mol burn gt-eph-xxx --force

Standard Demo (10 disks, ~2 minutes)

# Create wisp
WISP=$(bd mol wisp towers-of-hanoi-10 --json | jq -r '.new_epic_id')
echo "Created wisp: $WISP"

# Get all 1025 child IDs (1023 moves + setup + verify)
bd list --parent=$WISP --limit=2000 --json | jq -r '.[].id' > /tmp/ids.txt
wc -l /tmp/ids.txt  # Should show 1025

# Time the execution
START=$(date +%s)
while read id; do bd --no-daemon close "$id" >/dev/null 2>&1; done < /tmp/ids.txt
END=$(date +%s)
echo "Completed in $((END - START)) seconds"

# Verify completion
bd list --parent=$WISP --status=open  # Should be empty

# Cleanup
bd mol burn $WISP --force

Why Wisps?

The demo uses wisps (ephemeral molecules) because:

1. No Git Pollution: Wisps don’t sync to JSONL, keeping git history clean
2. Auto-Cleanup: Wisps can be burned without leaving tombstones
3. Speed: No export overhead during rapid closes
4. Appropriate Semantics: This is operational testing, not auditable work

Key Insights

bd ready Excludes Wisps

By design, bd ready filters out ephemeral issues:

"(i.ephemeral = 0 OR i.ephemeral IS NULL)", // Exclude wisps

For wisp execution, query children directly:

bd list --parent=$WISP --status=open

Dependencies Work Correctly

Each move depends on the previous one via needs:

[[steps]]
id = "move-42"
needs = ["move-41"]

This creates proper blocks dependencies. Parent-child relationships provide hierarchy only - they don’t block execution.

Close Speed

With bd --no-daemon close:

• ~109ms per close (serial)
• ~9 closes/second

Parallelization would improve throughput but requires careful dependency ordering.

Generating Larger Formulas

Use the generator script:

# Generate 15-disk formula (32K moves)
python3 scripts/gen_hanoi.py 15 > .beads/formulas/towers-of-hanoi-15.formula.toml

Warning: 20-disk formula is ~163MB and creates 1M+ issues. Only for stress testing post-launch.

Monitoring Progress

For long-running executions:

# Count closed issues
bd list --parent=$WISP --status=closed --json | jq 'length'

# Count remaining
bd list --parent=$WISP --status=open --json | jq 'length'

# Progress percentage
TOTAL=1025
CLOSED=$(bd list --parent=$WISP --status=closed --limit=2000 --json | jq 'length')
echo "$CLOSED / $TOTAL = $((CLOSED * 100 / TOTAL))%"

Session Cycling

The beauty of this demo: you can stop at any time and resume later.

# Session 1: Start the wisp, close some issues
WISP=$(bd mol wisp towers-of-hanoi-10 --json | jq -r '.new_epic_id')
# ... close some issues ...
# Context fills, need to cycle

gt handoff -s "Hanoi demo" -m "Wisp: $WISP, progress: 400/1025"

# Session 2: Resume where you left off
# (Read handoff mail for wisp ID)
bd list --parent=$WISP --status=open --limit=2000 --json | jq -r '.[].id' > /tmp/ids.txt
# ... continue closing ...

The molecule IS the state. No memory of previous session needed.