v0.20.0

.claude/commands/ir-reference.md

@@ -39,6 +39,8 @@ DFMember  (sealed)
 │   ├── DFDesignBlock           — module / design definition
 │   ├── DomainBlock             — clock-domain grouping
 │   ├── ProcessBlock            — always / process block
+│   ├── ForkBlock               — fork-join (forkJoin/forkJoinAny/forkJoinNone); join mode
+│   ├── LocalBlock              — local statement block (locally:); a fork branch when owned by ForkBlock
 │   ├── StepBlock               — FSM step
 │   ├── DFConditional.Block     — if / match clause
 │   │   ├── DFIfElseBlock
@@ -49,7 +51,6 @@ DFMember  (sealed)
 ├── DFConditional.Header    — if / match header expression
 │   ├── DFIfHeader
 │   └── DFMatchHeader
-├── DFInterfaceOwner        — interface abstraction
 └── DFRange                 — for-loop range
 ```
 
@@ -372,7 +373,7 @@ type PortByNameSelect.Ref = DFRef.TwoWay[DFDesignInst, PortByNameSelect]
 
 ```scala
 final case class DFNet(
-    lhsRef:   DFNet.Ref,   // DFRef.TwoWay[DFVal | DFInterfaceOwner, DFNet]
+    lhsRef:   DFNet.Ref,   // DFRef.TwoWay[DFVal, DFNet]
     op:       DFNet.Op,
     rhsRef:   DFNet.Ref,
     ownerRef: DFOwner.Ref,
@@ -396,8 +397,8 @@ DFNet.Assignment(toVal, fromVal)   // Assignment or NBAssignment; toVal and from
 DFNet.BAssignment(toVal, fromVal)  // blocking only (op == Assignment)
 DFNet.NBAssignment(toVal, fromVal) // non-blocking only (op == NBAssignment)
 DFNet.Connection(toVal, fromVal, swapped)
-  // toVal: DFVal.Dcl | DFVal.Special | DFInterfaceOwner
-  // fromVal: DFVal | DFInterfaceOwner
+  // toVal: DFVal.Dcl | DFVal.PortByNameSelect | DFVal.Special
+  // fromVal: DFVal
   // swapped: Boolean — true if lhs/rhs were physically reversed
 ```
 
@@ -468,7 +469,6 @@ enum InstMode.BlackBox: NA, Files(path), Library(libName, nameSpace), VendorIP(v
 
 **Extension methods:**
 ```scala
-design.isDuplicate          // tagged DuplicateTag — has NO members in DB (ports/domains removed)
 design.isBlackBox           // instMode is BlackBox
 design.isVendorIPBlackbox
 design.inSimulation         // instMode is Simulation
@@ -511,6 +511,29 @@ final case class ProcessBlock.Sensitivity.List(refs: List[DFVal.Ref])  // proces
 
 ---
 
+### ForkBlock & LocalBlock
+```scala
+final case class ForkBlock(
+    join:     ForkBlock.Join,   // All | Any | None
+    ownerRef: DFOwner.Ref,
+    meta:     Meta,
+    tags:     DFTags
+)
+enum ForkBlock.Join: All, Any, None   // forkJoin / forkJoinAny / forkJoinNone
+
+final case class LocalBlock(            // produced by `locally:`
+    ownerRef: DFOwner.Ref,
+    meta:     Meta,
+    tags:     DFTags
+)
+```
+ED-domain only (for now). A `LocalBlock` whose `getOwner` is a `ForkBlock` is a concurrent
+fork branch; elsewhere it is a plain local statement scope. SystemVerilog emits both natively
+(`fork…join[_any|_none]`, `begin[: name]…end`); `DropForkJoins` lowers forks to processes +
+handshake signals for VHDL/old-Verilog, and `DropLocalBlocks` flattens local blocks for VHDL.
+
+---
+
 ### StepBlock
 ```scala
 final case class StepBlock(
@@ -783,7 +806,6 @@ DFTags.empty
 
 **Built-in tags:**
 ```scala
-case object DuplicateTag      // duplicate design instance — NO members in DB
 case object IteratorTag       // Dcl is a for-loop iterator variable
 case object IdentTag          // Alias.AsIs is a pure identity (named alias of itself)
 case object BindTag           // Alias is a pattern-match bind variable
@@ -863,10 +885,6 @@ db.inSimulation           // top has no ports (simulation context)
 db.inBuild                // top has a device constraint tag
 ```
 
-**Design duplication properties:**
-
-Duplicate designs (tagged `DuplicateTag`) have **no members** in the DB — their ports, domain blocks, and other members are removed during immutable DB creation. 
-
 **Patching:**
 ```scala
 db.patch(patches: List[(DFMember, Patch)]): DB

.claude/commands/new-stage.md

@@ -129,7 +129,6 @@ DFMember (sealed)
 │   ├── StepBlock        ─ RT step (FSM state)
 │   └── DFConditional.Block ─ if/match/while clause
 ├── DFConditional.Header ─ if/match/while header
-├── DFInterfaceOwner
 └── DFRange
 ```
 
@@ -1072,9 +1071,7 @@ abstract class StageSpec(stageCreatesUnrefAnons: Boolean = false)
     fails with "wrong number of argument patterns" because `DFForBlock` has multiple fields. Use a
     type pattern instead: `case x: DFLoop.DFForBlock`. The same applies to other multi-field IR
     case classes that have no dedicated single-argument unapply.
-16. **Assuming duplicate designs have members** — designs tagged `DuplicateTag` have **no members**
-    in the DB (ports, domain blocks, and values are removed during immutable DB creation). 
-17. **Rewriting nested same-kind constructs in one pass** — if your stage rewrites a construct that
+16. **Rewriting nested same-kind constructs in one pass** — if your stage rewrites a construct that
     can nest inside another of the same kind (nested `for` loops, steps-in-conditionals nested in
     steps, etc.) via a `Move` / `ReplaceWithLast(ChangeRefAndRemove)` plus a body-anchored satellite
     patch, doing the outer and inner in one patch list conflicts: the inner appears both in the

CLAUDE.md

@@ -16,7 +16,7 @@ Outputs: Verilog, SystemVerilog, VHDL.
 
 ## Build System
 
-**Tool**: SBT 1.12.9 — **Scala**: 3.8.3 (nightly resolver enabled)
+**Tool**: SBT 1.12.12 — **Scala**: 3.8.4 (nightly resolver enabled)
 
 ```bash
 sbtn compile          # compile all subprojects

build.sbt

@@ -6,7 +6,7 @@ commands += DFHDLCommands.docExamplesRefUpdate
 
 // format: off
 val projectName = "dfhdl"
-val compilerVersion = "3.8.3"
+val compilerVersion = "3.8.4"
 
 inThisBuild(
   List(

compiler/ir/src/main/scala/dfhdl/compiler/analysis/DFOwnerAnalysis.scala

@@ -2,7 +2,6 @@ package dfhdl.compiler
 package analysis
 import dfhdl.internals.*
 import ir.*
-import scala.annotation.tailrec
 import scala.collection.mutable
 extension (owner: DFOwner)
   def members(memberView: MemberView)(using MemberGetSet): List[DFMember] =
@@ -12,7 +11,6 @@ extension (owner: DFOwner)
     val last = owner match
       case block: DFDesignBlock => designDB.designMemberTable(block).lastOption
       case block: DFBlock       => designDB.blockMemberTable(block).lastOption
-      case _                    => designDB.ownerMemberTable(owner).lastOption
     last match
       // if last member is an owner then we search further
       case Some(o: DFOwner) =>
@@ -22,15 +20,6 @@ extension (owner: DFOwner)
       case x => x
 end extension
 
-extension (domainOwner: DFDomainOwner)
-  // true if the domainOwner is dependent at any level of thatDomainOwner's configuration
-  @tailrec def isDependentOn(thatDomainOwner: DFDomainOwner)(using getSet: MemberGetSet): Boolean =
-    getSet.designDB.dependentRTDomainOwners.get(domainOwner) match
-      case Some(dependency) =>
-        if (dependency == thatDomainOwner) true
-        else dependency.isDependentOn(thatDomainOwner)
-      case None => false
-
 extension (design: DFDesignBlock)
   // collect all local parameters that are used in IOs
   def getIOLocalParams(using getSet: MemberGetSet): List[DFVal.CanBeExpr] =

compiler/ir/src/main/scala/dfhdl/compiler/analysis/StateAnalysis.scala

@@ -153,7 +153,7 @@ object StateAnalysis:
     given DFBlock = currentBlock
     remaining match
       case (nextBlock: DFBlock) :: rs if nextBlock.getOwnerBlock == currentBlock => // entering child block
-        val (updatedSet, updatedScopeMap): (Set[DFVal], AssignMap) = nextBlock match
+        val (updatedSet, updatedScopeMap) = nextBlock match
           case cb: DFConditional.Block =>
             cb.guardRef.get match
               case dfVal: DFVal => consumeFrom(dfVal, scopeMap, currentSet)
@@ -167,7 +167,7 @@ object StateAnalysis:
           if r.getOwnerBlock == currentBlock && checkedDomain(
             currentBlock.getThisOrOwnerDomain.domainType
           ) => // checking member consumers
-        val (updatedSet, updatedScopeMap): (Set[DFVal], AssignMap) = r match
+        val (updatedSet, updatedScopeMap) = r match
           case net @ DFNet.Assignment(toVal, fromVal) =>
             (consumeFrom(fromVal, scopeMap, currentSet), assignTo(toVal, scopeMap))
           case net @ DFNet.Connection(toVal: DFVal, fromVal: DFVal, _) =>