fix: go starter kit refresh + ci

.github/workflows/test-go-agent.yaml

@@ -0,0 +1,64 @@
+name: Test Go Starter Kit
+
+# Public repo: this runs on GitHub-hosted runners (ubuntu-latest), never the
+# self-hosted homeserver runners, so untrusted fork PRs can't execute on our
+# infrastructure.
+#
+# The engine's JSON schema is the source of truth for the wire protocol. This
+# workflow validates the Go starter kit's fixtures against that schema, and is
+# triggered whenever the schema changes — so a protocol update to the engine
+# surfaces any drift in the Go kit immediately.
+
+on:
+    push:
+        branches:
+            - master
+    pull_request:
+        branches:
+            - master
+        paths:
+            - "agents/go/**"
+            - "engine/bomberland-engine/src/runtime-validation/validation.schema.json"
+            - ".github/workflows/test-go-agent.yaml"
+    workflow_dispatch:
+
+concurrency:
+    group: test-go-agent-${{ github.ref }}
+    cancel-in-progress: true
+
+env:
+    ENGINE_SCHEMA: engine/bomberland-engine/src/runtime-validation/validation.schema.json
+
+jobs:
+    test:
+        runs-on: ubuntu-latest
+        timeout-minutes: 15
+        steps:
+            - name: Checkout code
+              uses: actions/checkout@v4
+
+            - name: Set up Go
+              uses: actions/setup-go@v5
+              with:
+                  go-version: stable
+                  cache-dependency-path: agents/go/go.sum
+
+            # The engine schema is the source of truth. Fail if the kit's bundled copy has
+            # drifted from it — that copy is what the Docker build and standalone clones use,
+            # since they don't have the engine tree available.
+            - name: Check bundled schema is in sync with engine
+              run: |
+                  if ! cmp -s "$ENGINE_SCHEMA" agents/go/validation.schema.json; then
+                    echo "::error::agents/go/validation.schema.json is out of sync with $ENGINE_SCHEMA"
+                    echo "Re-sync with: cp $ENGINE_SCHEMA agents/go/validation.schema.json"
+                    diff -u agents/go/validation.schema.json "$ENGINE_SCHEMA" || true
+                    exit 1
+                  fi
+
+            # Validate fixtures against the engine's live schema (not just the bundled copy),
+            # so fixture/protocol drift fails CI even before the copy is re-synced.
+            - name: Run Go tests against engine schema
+              working-directory: agents/go
+              env:
+                  BOMBERLAND_SCHEMA_PATH: ${{ github.workspace }}/engine/bomberland-engine/src/runtime-validation/validation.schema.json
+              run: go test ./... -count=1

README.md

@@ -45,7 +45,7 @@ docker-compose up --abort-on-container-exit --force-recreate
 | Python3-gym-wrapper | [Link](https://github.com/CoderOneHQ/bomberland/tree/master/agents/python3)    | Open AI Gym wrapper                                | ✅          | Coder One                               |
 | TypeScript          | [Link](https://github.com/CoderOneHQ/bomberland/tree/master/agents/typescript) | Basic TypeScript starter                           | ✅          | Coder One                               |
 | TypeScript-fwd      | [Link](https://github.com/CoderOneHQ/bomberland/tree/master/agents/typescript) | Includes example for using forward model simulator | ❌          | Coder One                               |
-| Go                  | [Link](https://github.com/CoderOneHQ/bomberland/tree/master/agents/go)         | Basic Go starter                                   | ❌          | [dtitov](https://github.com/dtitov)     |
+| Go                  | [Link](https://github.com/CoderOneHQ/bomberland/tree/master/agents/go)         | Basic Go starter                                   | ✅          | [dtitov](https://github.com/dtitov)     |
 | C++                 | [Link](https://github.com/CoderOneHQ/bomberland/tree/master/agents/cpp)        | Basic C++ starter                                  | ✅          | [jfbogusz](https://github.com/jfbogusz) |
 | Rust                | [Link](https://github.com/CoderOneHQ/bomberland/tree/master/agents/rust)       | Basic Rust starter                                 | ❌          | [K-JBoon](https://github.com/K-JBoon)   |
 

agents/go/bomberland/game_state_test.go

@@ -4,14 +4,26 @@ import (
 	"encoding/json"
 	"github.com/stretchr/testify/assert"
 	"github.com/xeipuuv/gojsonschema"
+	"os"
 	"path/filepath"
 	"testing"
 )
 
 func TestJSONSchema(t *testing.T) {
-	abs, err := filepath.Abs("../validation.schema.json")
+	// The engine's schema is the source of truth. CI points BOMBERLAND_SCHEMA_PATH at
+	// engine/bomberland-engine/src/runtime-validation/validation.schema.json so fixtures are
+	// validated against the live engine contract; the bundled copy is the fallback used by the
+	// Docker build and standalone clones (which don't have the engine tree available).
+	schemaPath := os.Getenv("BOMBERLAND_SCHEMA_PATH")
+	if schemaPath == "" {
+		schemaPath = "../validation.schema.json"
+	}
+	abs, err := filepath.Abs(schemaPath)
 	assert.NoError(t, err)
-	schemaLoader := gojsonschema.NewReferenceLoader("file://" + abs)
+	// Validate against the ServerPacket union specifically. The document root only holds
+	// `definitions` (no root constraints), so referencing it directly would accept anything;
+	// the fragment pins validation to the real server->client packet shapes.
+	schemaLoader := gojsonschema.NewReferenceLoader("file://" + abs + "#/definitions/ServerPacket")
 	tests := []struct {
 		name    string
 		payload interface{}
@@ -161,10 +173,10 @@ func createMockTickPacket(t *testing.T, tickNumber int, events interface{}) map[
 func getMockState(t *testing.T) interface{} {
 	var mockState interface{}
 	err := json.Unmarshal([]byte(`
-{"agents": {"a": {"agent_id": "a", "unit_ids": ["c", "e", "g"]}, "b": {"agent_id": "b", "unit_ids": ["d", "f", "h"]}}, "unit_state": {"c": {"coordinates": [3, 10], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "c", "agent_id": "a", "invulnerability": 0}, "d": {"coordinates": [11, 10], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "d", "agent_id": "b", "invulnerability": 0}, "e": {"coordinates": [1, 9], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "e", "agent_id": "a", "invulnerability": 0}, "f": {"coordinates": [13, 9], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "f", "agent_id": "b", "invulnerability": 0}, "g": {"coordinates": [12, 7], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "g", "agent_id": "a", "invulnerability": 0}, "h": {"coordinates": [2, 7], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "h", "agent_id": "b", "invulnerability": 0}}, "entities": [{"created": 0, "x": 11, "y": 7, "type": "m"}, {"created": 0, "x": 3, "y": 7, "type": "m"}, {"created": 0, "x": 10, "y": 11, "type": "m"}, {"created": 0, "x": 4, "y": 11, "type": "m"}, {"created": 0, "x": 11, "y": 2, "type": "m"}, {"created": 0, "x": 3, "y": 2, "type": "m"}, {"created": 0, "x": 4, "y": 8, "type": "m"}, {"created": 0, "x": 10, "y": 8, "type": "m"}, {"created": 0, "x": 14, "y": 14, "type": "m"}, {"created": 0, "x": 0, "y": 14, "type": "m"}, {"created": 0, "x": 13, "y": 13, "type": "m"}, {"created": 0, "x": 1, "y": 13, "type": "m"}, {"created": 0, "x": 14, "y": 0, "type": "m"}, {"created": 0, "x": 0, "y": 0, "type": "m"}, {"created": 0, "x": 2, "y": 3, "type": "m"}, {"created": 0, "x": 12, "y": 3, "type": "m"}, {"created": 0, "x": 3, "y": 14, "type": "m"}, {"created": 0, "x": 11, "y": 14, "type": "m"}, {"created": 0, "x": 0, "y": 1, "type": "m"}, {"created": 0, "x": 14, "y": 1, "type": "m"}, {"created": 0, "x": 5, "y": 2, "type": "m"}, 
+{"game_id": "dev-game", "agents": {"a": {"agent_id": "a", "unit_ids": ["c", "e", "g"]}, "b": {"agent_id": "b", "unit_ids": ["d", "f", "h"]}}, "unit_state": {"c": {"coordinates": [3, 10], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "c", "agent_id": "a", "invulnerable": 0, "stunned": 0}, "d": {"coordinates": [11, 10], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "d", "agent_id": "b", "invulnerable": 0, "stunned": 0}, "e": {"coordinates": [1, 9], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "e", "agent_id": "a", "invulnerable": 0, "stunned": 0}, "f": {"coordinates": [13, 9], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "f", "agent_id": "b", "invulnerable": 0, "stunned": 0}, "g": {"coordinates": [12, 7], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "g", "agent_id": "a", "invulnerable": 0, "stunned": 0}, "h": {"coordinates": [2, 7], "hp": 3, "inventory": {"bombs": 3}, "blast_diameter": 3, "unit_id": "h", "agent_id": "b", "invulnerable": 0, "stunned": 0}}, "entities": [{"created": 0, "x": 11, "y": 7, "type": "m"}, {"created": 0, "x": 3, "y": 7, "type": "m"}, {"created": 0, "x": 10, "y": 11, "type": "m"}, {"created": 0, "x": 4, "y": 11, "type": "m"}, {"created": 0, "x": 11, "y": 2, "type": "m"}, {"created": 0, "x": 3, "y": 2, "type": "m"}, {"created": 0, "x": 4, "y": 8, "type": "m"}, {"created": 0, "x": 10, "y": 8, "type": "m"}, {"created": 0, "x": 14, "y": 14, "type": "m"}, {"created": 0, "x": 0, "y": 14, "type": "m"}, {"created": 0, "x": 13, "y": 13, "type": "m"}, {"created": 0, "x": 1, "y": 13, "type": "m"}, {"created": 0, "x": 14, "y": 0, "type": "m"}, {"created": 0, "x": 0, "y": 0, "type": "m"}, {"created": 0, "x": 2, "y": 3, "type": "m"}, {"created": 0, "x": 12, "y": 3, "type": "m"}, {"created": 0, "x": 3, "y": 14, "type": "m"}, {"created": 0, "x": 11, "y": 14, "type": "m"}, {"created": 0, "x": 0, "y": 1, "type": "m"}, {"created": 0, "x": 14, "y": 1, "type": "m"}, {"created": 0, "x": 5, "y": 2, "type": "m"}, 
     {"created": 0, "x": 9, "y": 2, "type": "m"}, {"created": 0, "x": 9, "y": 6, "type": "m"}, {"created": 0, "x": 5, "y": 6, "type": "m"}, {"created": 0, "x": 11, "y": 13, "type": "m"}, {"created": 0, "x": 
     3, "y": 13, "type": "m"}, {"created": 0, "x": 2, "y": 10, "type": "m"}, {"created": 0, "x": 12, "y": 10, "type": "m"}, {"created": 0, "x": 2, "y": 13, "type": "m"}, {"created": 0, "x": 12, "y": 13, "type": "m"}, {"created": 0, "x": 12, "y": 6, "type": "m"}, {"created": 0, "x": 2, "y": 6, "type": "m"}, {"created": 0, "x": 1, "y": 10, "type": "m"}, {"created": 0, "x": 13, "y": 10, "type": "m"}, {"created": 0, "x": 1, "y": 6, "type": "m"}, {"created": 0, "x": 13, "y": 6, "type": "m"}, {"created": 0, "x": 9, "y": 12, "type": "m"}, {"created": 0, "x": 5, "y": 12, "type": "m"}, {"created": 0, "x": 1, "y": 0, "type": "m"}, {"created": 0, "x": 13, "y": 0, "type": "m"}, {"created": 0, "x": 14, "y": 2, "type": "m"}, {"created": 0, "x": 0, "y": 2, "type": "m"}, {"created": 0, "x": 10, "y": 1, "type": "m"}, {"created": 0, "x": 4, "y": 1, "type": "m"}, {"created": 0, "x": 11, "y": 8, "type": "m"}, {"created": 0, "x": 3, "y": 8, "type": "m"}, {"created": 0, "x": 0, "y": 6, "type": "m"}, {"created": 0, "x": 14, "y": 6, "type": "m"}, {"created": 0, "x": 12, "y": 5, "type": "m"}, {"created": 0, "x": 2, "y": 5, "type": "m"}, {"created": 0, "x": 1, "y": 3, "type": "w", "hp": 1}, {"created": 0, "x": 13, "y": 3, "type": "w", "hp": 1}, {"created": 0, "x": 1, "y": 8, "type": "w", "hp": 1}, {"created": 0, "x": 13, "y": 8, "type": "w", "hp": 1}, {"created": 0, "x": 0, "y": 8, "type": "w", "hp": 1}, {"created": 0, "x": 14, "y": 8, "type": "w", "hp": 1}, {"created": 0, "x": 6, "y": 3, "type": "w", "hp": 1}, {"created": 0, "x": 8, "y": 3, "type": "w", "hp": 1}, {"created": 0, "x": 6, "y": 1, "type": "w", "hp": 1}, {"created": 0, "x": 8, "y": 1, "type": "w", "hp": 1}, {"created": 0, "x": 9, "y": 1, "type": "w", "hp": 1}, {"created": 0, "x": 5, "y": 1, "type": "w", "hp": 1}, {"created": 0, "x": 13, "y": 14, "type": "w", "hp": 1}, {"created": 0, "x": 1, "y": 14, "type": "w", "hp": 1}, {"created": 0, "x": 5, "y": 9, "type": "w", "hp": 1}, {"created": 0, "x": 9, "y": 9, "type": "w", "hp": 1}, {"created": 0, "x": 3, "y": 1, "type": "w", "hp": 1}, {"created": 0, "x": 11, "y": 1, "type": "w", "hp": 1}, {"created": 0, "x": 13, "y": 11, "type": "w", "hp": 1}, {"created": 0, "x": 1, "y": 11, "type": "w", "hp": 1}, {"created": 0, "x": 8, "y": 12, "type": "w", "hp": 1}, {"created": 0, "x": 6, "y": 12, "type": "w", "hp": 1}, {"created": 0, "x": 14, "y": 3, "type": "w", "hp": 1}, {"created": 0, "x": 0, "y": 3, "type": "w", 
-    "hp": 1}, {"created": 0, "x": 10, "y": 13, "type": "w", "hp": 1}, {"created": 0, "x": 4, "y": 13, "type": "w", "hp": 1}, {"created": 0, "x": 14, "y": 13, "type": "w", "hp": 1}, {"created": 0, "x": 0, "y": 13, "type": "w", "hp": 1}, {"created": 0, "x": 10, "y": 14, "type": "w", "hp": 1}, {"created": 0, "x": 4, "y": 14, "type": "w", "hp": 1}, {"created": 0, "x": 5, "y": 3, "type": "w", "hp": 1}, {"created": 0, "x": 9, "y": 3, "type": "w", "hp": 1}, {"created": 0, "x": 2, "y": 11, "type": "w", "hp": 1}, {"created": 0, "x": 12, "y": 11, "type": "w", "hp": 1}, {"created": 0, "x": 10, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 4, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 9, "y": 0, "type": "w", "hp": 1}, {"created": 0, "x": 5, "y": 0, "type": "w", "hp": 1}, {"created": 0, "x": 1, "y": 4, "type": "w", "hp": 1}, {"created": 0, "x": 13, "y": 4, "type": "w", "hp": 1}, {"created": 0, "x": 1, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 13, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 8, "y": 5, "type": "w", "hp": 1}, {"created": 0, "x": 6, "y": 5, "type": "w", "hp": 1}, {"created": 0, "x": 6, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 8, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 0, "y": 4, "type": "w", "hp": 1}, {"created": 0, "x": 14, "y": 4, "type": "w", "hp": 1}, {"created": 0, "x": 13, "y": 1, "type": "w", "hp": 1}, {"created": 0, "x": 1, "y": 1, "type": "w", "hp": 1}, {"created": 0, "x": 5, "y": 14, "type": "w", "hp": 1}, {"created": 0, "x": 9, "y": 14, "type": "w", "hp": 1}, {"created": 0, "x": 14, "y": 11, "type": "w", "hp": 1}, {"created": 0, "x": 0, "y": 11, "type": "w", "hp": 1}, {"created": 0, "x": 5, "y": 5, "type": "w", "hp": 1}, {"created": 0, "x": 9, "y": 5, "type": "w", "hp": 1}, {"created": 0, "x": 10, "y": 4, "type": "o", "hp": 3}, {"created": 0, "x": 4, "y": 4, "type": "o", "hp": 3}, {"created": 0, "x": 9, "y": 11, "type": "o", "hp": 3}, {"created": 0, "x": 5, "y": 11, "type": "o", "hp": 3}, {"created": 0, "x": 4, "y": 12, "type": "o", "hp": 3}, {"created": 0, "x": 10, "y": 12, "type": "o", "hp": 3}, {"created": 0, "x": 2, "y": 1, "type": "o", "hp": 3}, {"created": 0, "x": 12, "y": 1, "type": "o", "hp": 3}, {"created": 0, "x": 10, "y": 6, "type": "o", "hp": 3}, {"created": 0, "x": 4, "y": 6, "type": "o", "hp": 3}, {"created": 0, "x": 11, "y": 3, "type": "o", "hp": 3}, {"created": 0, "x": 3, "y": 3, "type": "o", "hp": 3}, {"created": 0, "x": 2, "y": 4, "type": "o", "hp": 3}, {"created": 0, "x": 12, "y": 4, "type": "o", "hp": 3}], "world": {"width": 15, "height": 15}, "tick": 0, "config": {"tick_rate_hz": 10, "game_duration_ticks": 1, "fire_spawn_interval_ticks": 5}, "connection": {"id": 2, "role": "agent", "agent_id": "b"}}
+    "hp": 1}, {"created": 0, "x": 10, "y": 13, "type": "w", "hp": 1}, {"created": 0, "x": 4, "y": 13, "type": "w", "hp": 1}, {"created": 0, "x": 14, "y": 13, "type": "w", "hp": 1}, {"created": 0, "x": 0, "y": 13, "type": "w", "hp": 1}, {"created": 0, "x": 10, "y": 14, "type": "w", "hp": 1}, {"created": 0, "x": 4, "y": 14, "type": "w", "hp": 1}, {"created": 0, "x": 5, "y": 3, "type": "w", "hp": 1}, {"created": 0, "x": 9, "y": 3, "type": "w", "hp": 1}, {"created": 0, "x": 2, "y": 11, "type": "w", "hp": 1}, {"created": 0, "x": 12, "y": 11, "type": "w", "hp": 1}, {"created": 0, "x": 10, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 4, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 9, "y": 0, "type": "w", "hp": 1}, {"created": 0, "x": 5, "y": 0, "type": "w", "hp": 1}, {"created": 0, "x": 1, "y": 4, "type": "w", "hp": 1}, {"created": 0, "x": 13, "y": 4, "type": "w", "hp": 1}, {"created": 0, "x": 1, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 13, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 8, "y": 5, "type": "w", "hp": 1}, {"created": 0, "x": 6, "y": 5, "type": "w", "hp": 1}, {"created": 0, "x": 6, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 8, "y": 2, "type": "w", "hp": 1}, {"created": 0, "x": 0, "y": 4, "type": "w", "hp": 1}, {"created": 0, "x": 14, "y": 4, "type": "w", "hp": 1}, {"created": 0, "x": 13, "y": 1, "type": "w", "hp": 1}, {"created": 0, "x": 1, "y": 1, "type": "w", "hp": 1}, {"created": 0, "x": 5, "y": 14, "type": "w", "hp": 1}, {"created": 0, "x": 9, "y": 14, "type": "w", "hp": 1}, {"created": 0, "x": 14, "y": 11, "type": "w", "hp": 1}, {"created": 0, "x": 0, "y": 11, "type": "w", "hp": 1}, {"created": 0, "x": 5, "y": 5, "type": "w", "hp": 1}, {"created": 0, "x": 9, "y": 5, "type": "w", "hp": 1}, {"created": 0, "x": 10, "y": 4, "type": "o", "hp": 3}, {"created": 0, "x": 4, "y": 4, "type": "o", "hp": 3}, {"created": 0, "x": 9, "y": 11, "type": "o", "hp": 3}, {"created": 0, "x": 5, "y": 11, "type": "o", "hp": 3}, {"created": 0, "x": 4, "y": 12, "type": "o", "hp": 3}, {"created": 0, "x": 10, "y": 12, "type": "o", "hp": 3}, {"created": 0, "x": 2, "y": 1, "type": "o", "hp": 3}, {"created": 0, "x": 12, "y": 1, "type": "o", "hp": 3}, {"created": 0, "x": 10, "y": 6, "type": "o", "hp": 3}, {"created": 0, "x": 4, "y": 6, "type": "o", "hp": 3}, {"created": 0, "x": 11, "y": 3, "type": "o", "hp": 3}, {"created": 0, "x": 3, "y": 3, "type": "o", "hp": 3}, {"created": 0, "x": 2, "y": 4, "type": "o", "hp": 3}, {"created": 0, "x": 12, "y": 4, "type": "o", "hp": 3}, {"created": 10, "x": 7, "y": 7, "type": "fp", "expires": 50, "hp": 1}, {"created": 10, "x": 6, "y": 7, "type": "bp", "expires": 50, "hp": 1}], "world": {"width": 15, "height": 15}, "tick": 0, "config": {"tick_rate_hz": 10, "game_duration_ticks": 1, "fire_spawn_interval_ticks": 5}, "connection": {"id": 2, "role": "agent", "agent_id": "b"}}
 `), &mockState)
 	assert.NoError(t, err)
 	return mockState
@@ -198,7 +210,7 @@ func getMockTickExpiredPacket(t *testing.T) map[string]interface{} {
 func getMockUnitStatePayload(t *testing.T) interface{} {
 	var mockUnitStatePayload interface{}
 	err := json.Unmarshal([]byte(`
-{"coordinates": [3, 10], "hp": 3, "inventory": {"bombs": 2}, "blast_diameter": 3, "unit_id": "c", "agent_id": "a", "invulnerability": 0}
+{"coordinates": [3, 10], "hp": 3, "inventory": {"bombs": 2}, "blast_diameter": 3, "unit_id": "c", "agent_id": "a", "invulnerable": 0, "stunned": 0}
 `), &mockUnitStatePayload)
 	assert.NoError(t, err)
 	return mockUnitStatePayload

agents/go/main.go

@@ -69,7 +69,7 @@ func tickHandler(tickNumber float64, state map[string]interface{}) (err error) {
 		}
 		logrus.WithField("action", "detonate").Info()
 		x, y := getBombToDetonate(unitID, state)
-		if x > 0 && y > 0 {
+		if x >= 0 && y >= 0 {
 			err = gameState.SendDetonate(x, y, unitID)
 			if err != nil {
 				logrus.Error(err)
@@ -84,7 +84,9 @@ func tickHandler(tickNumber float64, state map[string]interface{}) (err error) {
 func getBombToDetonate(unitID string, state map[string]interface{}) (float64, float64) {
 	for _, iEntity := range state["entities"].([]interface{}) {
 		entity := iEntity.(map[string]interface{})
-		if entity["owner_unit_id"] == unitID && entity["type"] == "b" {
+		// Bombs are type "b"; the placing unit is identified by "unit_id"
+		// (the engine renamed this from the old "owner_unit_id").
+		if entity["unit_id"] == unitID && entity["type"] == "b" {
 			return entity["x"].(float64), entity["y"].(float64)
 		}
 	}