Core capabilities
Snapshot
Full design-state snapshot at any moment. Agents roll back to any snapshot when exploring optimization strategies and compare branch outcomes—snapshots anchor the Agent experiment loop.
Typed Delta
Structured difference between snapshots—not a raw diff but typed change records: which cells moved, nets rewired, timing paths affected. Agents use delta to understand precise change impact.
DirtySet
Tracks objects modified since last oracle verification. Incremental analysis scans only the dirty region, minimizing incremental compute cost.
CAS Commit
Compare-and-swap commit semantics. Multiple candidate plans cannot modify main head concurrently—CAS ensures one successful commit; others rebase to the latest snapshot and re-verify.
Stable ID
Stable object IDs across snapshots. Agents track the same cell/net across versions—position in snap_0001, move in snap_0007, timing slack in snap_0012.
Agent calling patterns
from ieda import AgentClient
client = AgentClient()
design = client.load_design("aes_core", tech="sky130")
# take a snapshot
snap = client.call("iDB.snapshot", design=design)
print(f"Snapshot: {snap.id}, cells={snap.cell_count}")
# compute delta between two snapshots
delta = client.call("iDB.delta", from_snap=snap1.id, to_snap=snap2.id)
print(f"Moved: {len(delta.moved_cells)}, New nets: {len(delta.new_nets)}")
# commit with CAS
result = client.call("iDB.commit",
design=design,
proposal=proposal,
expected_head="snap_7f3a")
assert result.committed, "CAS failed — rebase required"
{
"tool": "iDB.snapshot",
"arguments": {
"design_ref": "aes_core@sky130",
"label": "before iPL placement"
}
}
// Response
{ "snapshot": { "id": "snap_7f3a", "cell_count": 125430 } }
{
"tool": "iDB.delta",
"arguments": {
"from": "snap_7f3a",
"to": "snap_8b2c"
}
}
{
"tool": "iDB.commit",
"arguments": {
"proposal_id": "prop_a3k9",
"expected_head": "snap_7f3a"
}
}
# take a snapshot iDB::snapshot -label "before placement" # Returns: snap_7f3a # compute delta iDB::delta -from snap_7f3a -to snap_8b2c # CAS commit — only if head unchanged iDB::commit -proposal prop_a3k9 -expected_head snap_7f3a
Input / output contract
SnapshotRequest → SnapshotRef
SnapshotRequest {
design_ref: DesignRef // Design reference
label?: str // Optional snapshot label
}
SnapshotRef {
id: str // Unique snapshot ID, e.g. "snap_7f3a"
time: Timestamp // ISO 8601 timestamp
cell_count: int // Cell count at snapshot
net_count: int // Net count at snapshot
label?: str // Snapshot label
}DeltaRequest → DesignDelta
DeltaRequest {
from: SnapshotRef // Source snapshot
to: SnapshotRef // Target snapshot
scope?: DeltaScope // Optional scope filter (CELL | NET | TIMING | ALL)
}
DesignDelta {
moved_cells: []CellMove // Moved cells
new_nets: []NetChange // New or changed nets
timing_changes: []TimingDelta // Timing changes
drc_changes: []DRCDelta // DRC violation changes
}CommitRequest (CAS) → CommitResult
CommitRequest {
proposal_id: str // Proposal identifier
expected_head: str // Expected head snapshot for CAS
delta: DesignDelta // Proposed change delta
}
CommitResult {
committed: bool // Whether CAS succeeded
new_head?: str // New head snapshot ID on success
conflict_with?: str // Conflicting head snapshot ID on failure
reason?: str // Failure reason
}Place in architecture
┌──────────────────────────────────────┐
│ iDB │
│ (Unified design database—single source of truth) │
│ │
│ ┌─────────┐ ┌──────────┐ │
│ │Snapshot │ │ Delta │ │
│ │ Manager │ │ Engine │ │
│ └─────────┘ └──────────┘ │
│ ┌─────────┐ ┌──────────┐ │
│ │DirtySet │ │ CAS │ │
│ │ Tracker │ │ Service │ │
│ └─────────┘ └──────────┘ │
│ ┌─────────────────────────┐ │
│ │ Stable ID Registry │ │
│ └─────────────────────────┘ │
└──┬───────┬───────┬───────┬──────────┘
│ │ │ │
┌────────┴──┐ ┌──┴───┐ ┌─┴─────┐ └───┬──────
│ iPL │ │ iRT │ │ iSTA │ ... │
│ placement │ │route │ │timing │ │
└───────────┘ └──────┘ └───────┘ │
┌──────┴──────┐
│ Interface │
│ MCP/Py/Tcl │
└──────┬──────┘
│
LLM Agent