Only track conditionless edges in the conditionless-edge dedup set

[PratikDhanave]

Summary

Builder.AddDirectEdge appends every connection to wb.conditionlessConnections (builder.go), including conditional edges, but the duplicate check fires only when condition == nil and treats any entry in that list as a pre-existing conditionless edge. So a conditional edge added first on a source→target pair poisons the dedup set: a subsequent legitimate conditionless edge on the same pair is wrongly rejected.

Concrete trigger:

b.AddDirectEdge(a, b, false, func(any) bool { return true }) // conditional
b.AddEdge(a, b)                                              // conditionless
// => wb.err = "an edge from 'a' to 'b' already exists without a condition"

even though no conditionless edge exists. Via AddChain (which calls AddDirectEdge with idempotent=true), the same poisoning instead silently drops the chain edge (the dedup returns early without adding it).

Fix

Guard the append with condition == nil, so only conditionless edges populate the conditionless-edge dedup set — matching the field's name and sole purpose (it is read only by that dedup check).

Public API

No exported symbols change.

Tests

• TestBuilder_ConditionalEdgeDoesNotBlockConditionlessEdge — conditional then conditionless edge on the same pair now builds without error (fails before this change with the misleading duplicate error).
• TestBuilder_ConditionalEdgeDoesNotDropIdempotentConditionlessEdge — the idempotent path doesn't silently drop the conditionless edge.

go test ./workflow passes; gofmt clean.

[Copilot]

Pull request overview

Fixes a bug in workflow.Builder.AddDirectEdge where conditional edges were incorrectly recorded in the conditionless-edge dedup tracking set, causing subsequent legitimate conditionless edges on the same source→target pair to be rejected (or silently dropped on idempotent paths like AddChain).

Changes:

• Only append to wb.conditionlessConnections when condition == nil, aligning the data structure with its intended purpose.
• Add regression tests covering “conditional then conditionless” and the idempotent conditionless-edge path.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
workflow/builder.go	Fixes conditionless-edge dedup bookkeeping so conditional edges don’t poison the conditionless dedup set.
workflow/builder_conditional_edge_test.go	Adds regression tests for conditional-vs-conditionless edge interactions and idempotent insertion behavior.

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