feat: split the concept of hidden and impassable exits. add player_flag for discovered hidden exits.

3 files changed, 49 insertions, 1 deletions

diff --git a/internal/world/grid.go b/internal/world/grid.go
index 837f737..2ea897a 100644
--- a/internal/world/grid.go
+++ b/internal/world/grid.go
@@ -32,12 +32,15 @@ type RoomGrid struct {
 //     are then not followed, but any coordinate already assigned to it stands.
 //   - include, when non-nil, restricts placement to targets for which it returns
 //     true (pass nil to place every reachable target).
+//   - edgeInclude, when non-nil, restricts traversal to exits for which it
+//     returns true (pass nil to follow every exit whose target passes include).
+//     It receives (fromRoomID, dir, targetRoomID) and is checked before include.
 //   - onConflict, when non-nil, is called for each twist/overlap encountered.
 //
 // The first assignment to a room or cell always wins; conflicting placements are
 // skipped. In a world that passes grid validation there are no conflicts, so the
 // layout is unambiguous.
-func BuildGrid(seed int, load func(int) (*Room, bool), include func(int) bool, onConflict func(GridConflict)) RoomGrid {
+func BuildGrid(seed int, load func(int) (*Room, bool), include func(int) bool, edgeInclude func(int, ExitDir, int) bool, onConflict func(GridConflict)) RoomGrid {
 	g := RoomGrid{
 		Coord:  map[int][3]int{seed: {0, 0, 0}},
 		RoomAt: map[[3]int]int{{0, 0, 0}: seed},
diff --git a/internal/world/room.go b/internal/world/room.go
index 8843b9e..29cce0b 100644
--- a/internal/world/room.go
+++ b/internal/world/room.go
@@ -81,6 +81,7 @@ type ExitDef struct {
 	SetFlags       map[string]any      `yaml:"set_flags,omitempty"`
 	SetPlayerFlags map[string]any      `yaml:"set_player_flags,omitempty"`
 	Hidden         bool                `yaml:"hidden,omitempty"`
+	AlwaysBlocked  bool                `yaml:"always_blocked,omitempty"`
 }
 
 func (e *ExitDef) UnmarshalYAML(value *yaml.Node) error {
diff --git a/internal/world/room_test.go b/internal/world/room_test.go
index e7b1718..1ad974e 100644
--- a/internal/world/room_test.go
+++ b/internal/world/room_test.go
@@ -4,6 +4,8 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+
+	"gopkg.in/yaml.v3"
 )
 
 func writeRoom(t *testing.T, dir string, body string) {
@@ -90,3 +92,45 @@ func TestNormalizeObjectName(t *testing.T) {
 		}
 	}
 }
+
+func TestExitDefUnmarshalAlwaysBlocked(t *testing.T) {
+	y := `exits:
+  north:
+    room: 5
+    always_blocked: true
+  south: 3
+  east:
+    room: 7
+    hidden: true
+`
+	var room struct {
+		Exits map[ExitDir]ExitDef `yaml:"exits"`
+	}
+	if err := yaml.Unmarshal([]byte(y), &room); err != nil {
+		t.Fatalf("unmarshal: %v", err)
+	}
+	if len(room.Exits) != 3 {
+		t.Fatalf("expected 3 exits, got %d", len(room.Exits))
+	}
+	n := room.Exits[North]
+	if !n.AlwaysBlocked {
+		t.Error("north exit should have AlwaysBlocked=true")
+	}
+	if n.Room != 5 {
+		t.Errorf("north target = %d, want 5", n.Room)
+	}
+	s := room.Exits[South]
+	if s.Room != 3 {
+		t.Errorf("south target = %d, want 3", s.Room)
+	}
+	if s.AlwaysBlocked {
+		t.Error("south exit should not have AlwaysBlocked")
+	}
+	e := room.Exits[East]
+	if !e.Hidden {
+		t.Error("east exit should have Hidden=true")
+	}
+	if e.AlwaysBlocked {
+		t.Error("east exit should not have AlwaysBlocked")
+	}
+}