Merge pull request 'catalogue: say in the comments that a package may be declared by several modules (issue 628)' (#300) from fix/628-packages-are-shared into main

cmd/mesh-controller/acts.go

@@ -203,8 +203,9 @@ func seatDependenciesOnAssign(ctx context.Context, open *stores, node string, mo
 	if _, err := catalogue.AssignRefusal(shelf, node, assigned, adding); err != nil {
 		return nil, nil, err
 	}
-	// Two modules declaring one package, path or unit is refused before anything is recorded
-	// (novox/hq ADR 0210, 04-ISSUES/235): kept, the node would not resolve until one came off again.
+	// Two modules declaring one path or unit, or one package present and absent, is refused before anything
+	// is recorded (novox/hq ADR 0210, ADR 0303, 04-ISSUES/235): kept, the node would not resolve until one came
+	// off again. Two modules declaring one package present is not a collision (ADR 0303, issue 628).
 	if err := catalogue.CollisionRefusal(shelf, node, assigned, adding); err != nil {
 		return nil, nil, err
 	}

internal/catalogue/declaration.go

@@ -2551,8 +2551,8 @@ func onlyGroups(r map[string]any) bool {
 
 // generatedHere is what each computed module's generator answers for this machine, by module —
 // absent for a module whose machine is not yet part of what it generates — held to the rule every
-// module is held to: no two modules on a machine declare one path, unit, name or package (novox/hq
-// issue 190, step 5; ADR 0222).
+// module is held to: no two modules on a machine declare one path, unit or name, nor one package present
+// and absent (novox/hq issue 190, step 5; ADR 0222, ADR 0303).
 //
 // Resolution checks the catalogue's manifests, and a computed module's manifest has none of the
 // resources it will declare — they exist only once its generator has answered for this machine,

internal/catalogue/generated_collision_test.go

@@ -6,7 +6,8 @@ import (
 )
 
 // novox/hq issue 190, step 5 (ADR 0222): what the mesh computes for a module is held to the rule
-// every module is — no two modules on a machine declare one path, unit, name or package. The
+// every module is — no two modules on a machine declare one path, unit or name (a package may be declared by
+// several, novox/hq ADR 0303). The
 // private network once declared the container runtime's file and service beside the runtime's own
 // module, and nothing refused it, because the collision check only ever saw catalogue manifests.
 

internal/catalogue/seat_dependencies.go

@@ -331,12 +331,13 @@ func UnassignRefusal(catalogue map[string]Manifest, node string, assigned, remov
 }
 
 // CollisionRefusal is why assigning `adding` beside `assigned` is refused for what two modules
-// would both declare, or nothing (novox/hq ADR 0210 §1, 04-ISSUES/235).
+// would both declare, or nothing (novox/hq ADR 0210 §1, 04-ISSUES/235): one path, unit or name, or a package one
+// declares present and another absent. A package several modules declare present is no collision (ADR 0303).
 //
 // **Refused, not kept like an unresolved provision.** An assignment is otherwise kept when the
 // node does not resolve, because assignment is not an ordering: a consumer's provider can follow.
 // A collision is not an order anything can complete — no further assignment makes two owners of one
-// package one owner — and kept, it leaves the node unresolvable, so the next push of anything drops
+// file one owner — and kept, it leaves the node unresolvable, so the next push of anything drops
 // it from the mesh. Only collisions involving a module being added are refused; one already on the
 // node is `status`'s, and refusing an unrelated assignment for it would block its own remedy.
 func CollisionRefusal(catalogue map[string]Manifest, node string, assigned, adding []string) error {