Symptom

On the swarm canvas (ClientScreen), connection lines between nodes were display-only. The only way to remove a wiring edge was to open the downstream node’s editor → Sources tab → tap the “✕” next to a source. Ben asked for the connecting lines themselves to be clickable so a user can delete a connection directly from the graph while in the swarm screens.

Root cause

Not a bug — a missing affordance. The arcs are painted on full-canvas Canvas layers (DrawTargetingArcs / DrawInputArcs) that sit below the node composables and carry no pointerInput, so taps fell through them. Nodes are separate composables drawn on top, so the lines were never “enclosed” in node bounds — they just had no hit-testing.

Fix

Added connection-line selection + deletion, gated behind the existing canvas editMode:

• ConnectionHitTest.kt (new, commonMain): pure, Compose-free geometry — arcGeometry() reconstructs the exact quadratic bezier the renderer draws (same NODE_SIZE_DP/2 inset, 0.3·distance perpendicular control, SOURCE bows +90° / INPUT -90°) in layout space; distanceToArc()/hitTestArc() sample the curve; findConnectionAt() resolves the nearest source/input arc to a tap and returns a SelectedConnection(observerId, removedId, kind).
• ConnectNodesWiring.kt: added ConnectionKind + disconnect() — the inverse of the existing applyConnect(). Removes the edge from the observer node (the TargetingConnection.targetId, which owns the wiring) via the same withWiring/withInputs write path the Sources tab uses, then ClientNodeManager.submit() persists it (identical to ConnectNodesWizard).
• ClientScreen.kt: the existing container detectTapGestures now, in edit mode, inverts the graphicsLayer transform ((tap − center − pan) / scale) to layout space and hit-tests; a hit sets a local selectedConnection. A new ConnectionDeleteOverlay (inside the pan/zoom box, drawn last) highlights the arc in colorScheme.error and floats a circular delete button at its midpoint. No server/shared/model change — same mutation the editor already performs.

Prevention

• One source of truth for arc geometry. The hit-test must recompute the curve identically to the renderer or the clickable band drifts from the drawn line. arcGeometry() is the shared helper both should use; if the draw formulas in drawTargetingArc/drawInputArc ever change, change arcGeometry() in lockstep (a comment in each points at the other).
• Pure hit-test seam is unit-tested. ConnectionHitTestTest covers geometry, resolution, and disconnect() over Offset/fixture metadata — no Compose host, no platform expect-vals — so the math regresses loudly.
• Note on local verification: the Compose/Android Gradle build could not be exercised in the authoring sandbox — the org egress policy blocks api.foojay.io (the Oracle JDK 21 daemon toolchain) and maven.google.com (the Android Gradle Plugin), with a cold Gradle cache. The new logic was kept pure + unit-tested so CI (which has the provisioned toolchain) compiles and runs it; reviewers should rely on CI + the manual UI check below.