Hash-based IDs | Beads 简体中文

Understanding beads' collision-resistant ID system.

The Problem

Traditional sequential IDs (#1, #2, #3) break when:

Multiple agents create issues simultaneously
Different branches have independent numbering
Forks diverge and later merge

flowchart TD
    subgraph seq["Sequential IDs — collision on merge"]
        a1["agent A creates #7"] --> m1["merge: two different #7s ✗"]
        b1["agent B creates #7"] --> m1
    end
    subgraph hash["Hash IDs — no coordination needed"]
        a2["agent A creates bd-a1b2"] --> m2["merge: both IDs survive ✓"]
        b2["agent B creates bd-f14c"] --> m2
    end

The Solution

Beads uses hash-based IDs:

bd-a1b2c3    # Short hash
bd-f14c      # Even shorter
bd-a3f8e9.1  # Hierarchical (child of bd-a3f8e9)

Properties:

Globally unique (content-based hash)
No coordination needed between creators
Merge-friendly across branches
Predictable length (configurable)

How Hashes Work

IDs are generated from:

Issue title
Creation timestamp
Random salt

# Create issue - ID assigned automatically
bd create "Fix authentication bug"
# Returns: bd-7x2f

# The ID is deterministic for same content+timestamp

Hierarchical IDs

For epics and subtasks:

# Parent epic
bd create "Auth System" -t epic
# Returns: bd-a3f8e9

# Children auto-increment
bd create "Design UI" --parent bd-a3f8e9    # bd-a3f8e9.1
bd create "Backend" --parent bd-a3f8e9      # bd-a3f8e9.2
bd create "Tests" --parent bd-a3f8e9        # bd-a3f8e9.3

Benefits:

Clear parent-child relationship
No namespace collision (parent hash is unique)
Up to 3 levels of nesting

ID Configuration

Configure ID prefix and length:

# Set prefix (default: bd)
bd config set id.prefix myproject

# Set hash length (default: 4)
bd config set id.hash_length 6

# New issues use new format
bd create "Test"
# Returns: myproject-a1b2c3

Collision Handling

While rare, collisions are handled automatically:

On import, if hash collision detected
Beads appends disambiguator
Both issues preserved

# Check for collisions
bd info --schema --json | jq '.collision_count'

Working with IDs

# Partial ID matching
bd show a1b2     # Finds bd-a1b2...
bd show auth     # Fuzzy match by title

# Full ID required for ambiguous cases
bd show bd-a1b2c3d4

# List with full IDs
bd list --full-ids

Migration from Sequential IDs

If migrating from a system with sequential IDs:

# Bootstrap from a JSONL export (preserves original IDs in metadata)
bd init --from-jsonl old-issues.jsonl

# View original ID
bd show bd-new --json | jq '.original_id'

Best Practices

Use short references - bd-a1b2 is usually unique enough
Use --json for scripts - Parse full ID programmatically
Reference by hash in commits - Fixed bd-a1b2 in commit messages
Let hierarchies form naturally - Create epics, add children as needed