Add BUILD.bazel dependency linting (#5437)

* Add BUILD.bazel dependency linting

Adds tooling to enforce architectural boundaries in the codebase:

1. Shell script `scripts/check_build_deps.sh` with multiple modes:
   - Default: runs all checks and shows dependency counts
   - --ci: fails only on hard violations (src/main depends on src/test)
   - --strict: also fails if proto deps in library/ increase from baseline
   - --count: just show current dependency counts
   - --update-baseline: update the baseline file for tracking

2. Bazel test `//:build_deps_test` for integration with test suite

3. Baseline file `scripts/build_deps_baseline.txt` tracking proto dep count

Current enforced rules:
- src/main must not depend on src/test (enforced now)
- library/ proto dependencies tracked (167 currently, deproto in progress)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Update DEPROTO_PLAN.md with accurate proto import inventory

The previous status was inaccurate. This update:

- Corrects summary table: Availability, Command Choice Helpers,
  and other utilities still have Hostility proto imports
- Adds Phase 8b documenting Hostility proto migration (4 files)
- Updates detailed inventory showing actual 13 files with direct
  proto imports (vs 167 transitive deps from bazel query)
- Corrects success criteria checkboxes to reflect actual status
- Documents the grep command used to verify imports

The 167 proto deps from bazel query are transitive dependencies.
Only 13 files have direct proto imports:
- 5 boundary files (expected to keep proto)
- 4 files using Hostility proto (Phase 8b)
- 4 LLM prompt generator files (Phase 8)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

BUILD.bazel

@@ -32,3 +32,15 @@ nogo(
     vet = True,
     visibility = ["//visibility:public"],
 )
+
+# Dependency constraint tests
+# These verify architectural boundaries are maintained
+sh_test(
+    name = "build_deps_test",
+    srcs = ["scripts/check_build_deps.sh"],
+    args = ["--ci"],
+    tags = [
+        "local",  # Needs bazel query access
+        "no-sandbox",
+    ],
+)

docs/DEPROTO_PLAN.md

@@ -42,16 +42,17 @@
 | AI (`/ai/`) | **0** | ✅ **Complete** |
 | Actions (`/library/actions/impl/action/`) | **0** | ✅ **Complete** |
 | Commands (`/library/actions/impl/command/`) | **0** | ✅ **Complete** |
-| Availability (`/library/actions/availability/`) | **0** | ✅ **Complete** |
-| Command Choice Helpers (`/library/util/command_choice_helpers/`) | **0** | ✅ **Complete** |
-| View Filters (`/library/util/view_filters/`) | **0** | ✅ **Complete** (except boundary code) |
-| Other Utilities (`/library/util/`) | **0** | ✅ **Complete** |
+| Availability (`/library/actions/availability/`) | **2** | ⏳ Uses `Hostility` proto |
+| Command Choice Helpers (`/library/util/command_choice_helpers/`) | **1** | ⏳ Uses `Hostility` proto |
+| View Filters (`/library/util/view_filters/`) | **1** | Keep (boundary code for battles) |
+| Other Utilities (`/library/util/`) | **1** | ⏳ `FactionUtils` uses `Hostility` proto |
 | NewGameCreation (`/service/new_game_creation/`) | **0** | ✅ **Complete** (except input GameParameters proto) |
-| LLM Prompt Generators (`/library/actions/llm_prompt_generators/`) | **0** | ✅ **Complete** |
-| LLM Request Generators (`/library/actions/llm_request_generators/`) | **0** | ✅ **Complete** |
-| Root Library (`/library/`) | **7** | Boundary code (4 files) |
+| LLM Prompt Generators (`/library/actions/llm_prompt_generators/`) | **~8** | ⏳ Remaining work (4 files) |
+| Root Library (`/library/`) | **~7** | Boundary code (4 files) |
 
-**Total: ~7 proto imports remaining** (down from 149) - all in boundary code
+**Total: 13 files with proto imports in library/** (verified via `bazel query`)
+
+**Note:** The `bazel query` for proto dependencies returns 167 targets because it includes transitive dependencies. The actual direct proto imports are in only 13 files.
 
 ### Completed Phases
 
@@ -68,7 +69,7 @@
 | Phase 6c: AI Clients | **Complete** | AIClient, command choosers all protoless |
 | Phase 6d: CommandSelection | **Complete** | Renamed ScalaCommandSelection → CommandSelection |
 
-### Recent Completions (PRs #5326-#5431)
+### Recent Completions (PRs #5326-#5390)
 
 1. **CommandFactory protoless** - Now accepts/returns Scala `SelectedCommand` types
 2. **AI clients protoless** - `AIClient`, `MidGameAIClient`, all command choosers use Scala types
@@ -87,8 +88,6 @@
 15. **Remove proto ActionResult from Engine layer** (PR #5378) - Engine uses Scala `ActionResultT`
 16. **NewGameCreation protoless** (PR #5381) - Uses Scala types throughout, no proto conversion
 17. **PersistedHistory Scala API** (PR #5390) - New `apply` overload accepts `Vector[ActionResultT]` directly
-18. **All LLM prompt generators protoless** (PR #5429) - All 34 files converted to use `LlmRequestT` Scala types
-19. **All LLM request generators protoless** (PRs #5419-#5428) - Converted to use Scala `LlmRequestT` types
 
 ---
 
@@ -107,18 +106,31 @@
 
 **Pattern established**: Create Scala view type → Create converter → Update filter to return Scala type → Convert at edge.
 
-### Phase 8: LLM Prompt Generators ✅ Complete
+### Phase 8: LLM Prompt Generators ⏳ In Progress
 
-All 34 LLM prompt generator files have been converted to use Scala `LlmRequestT` types instead of proto types.
+**Status**: 4 files still have proto imports
 
-| File Category | Files | Status |
-|---------------|-------|--------|
-| Diplomacy prompts | 12 | ✅ Complete |
-| Quest prompts | 4 | ✅ Complete |
-| Chronicle prompts | 3 | ✅ Complete |
-| Other prompts | 15 | ✅ Complete |
+| File | Proto Imports | Notes |
+|------|---------------|-------|
+| `BattalionDescriptions.scala` | `BattalionTypeId`, `Battalion`, `BattalionView` | Used for battalion text generation |
+| `ChronicleEventTextGenerator.scala` | `EventForChronicle.*` | Converts chronicle events to text |
+| `GeneratorUtilities.scala` | `Date` | Date formatting |
+| `QuestEndedGeneratorUtilities.scala` | `BattalionTypeId`, `UnaffiliatedHeroQuest.*` | Quest text generation |
 
-**Migration completed in PR #5429**: All prompt generators now accept `LlmRequestT.*` Scala types (e.g., `LlmRequestT.DivineMessage`, `LlmRequestT.AllianceOfferMessage`). Converters are used at the boundary in `LlmResolver.scala` where needed.
+**Migration strategy**: Create Scala equivalents for these types or accept Scala types at the API boundary.
+
+### Phase 8b: Hostility Proto Migration ⏳ In Progress
+
+**Status**: 4 files use `net.eagle0.common.hostility.Hostility` proto
+
+| File | Usage |
+|------|-------|
+| `AvailableAttackDecisionCommandFactory.scala` | Checks hostility for attack decisions |
+| `AvailableFreeForAllDecisionCommandFactory.scala` | Checks hostility for FFA decisions |
+| `AttackDecisionCommandChooser.scala` | AI uses hostility for decisions |
+| `FactionUtils.scala` | `Hostility` conversion utility |
+
+**Migration strategy**: Create a Scala `Hostility` enum and migrate these 4 files. The enum is simple (ALLIED, NEUTRAL, HOSTILE).
 
 ### Phase 9: Remaining Utilities ✅ Complete
 
@@ -163,12 +175,12 @@ All 34 LLM prompt generator files have been converted to use Scala `LlmRequestT`
 - `*Converter.scala` - Explicit conversion utilities
 - `PersistedHistory.scala` - Disk persistence
 
-### Remaining Proto Usage (Boundary Only) ✅
+### Remaining Proto Usage ⏳
 
-All remaining proto usage is at system boundaries, which is expected and appropriate:
-
-- BattleFilter (1 import) - Keep (boundary for Shardok battle views)
-- Root library boundary code (7 imports in 4 files) - Keep (gRPC/persistence boundaries)
+- LLM prompt generators (56 imports in 34 files) - Medium priority
+- LLM request generators (2 imports in 1 file) - Medium priority
+- BattleFilter (1 import) - Keep (boundary)
+- Root library boundary code (7 imports in 4 files) - Keep (boundary)
 
 ---
 
@@ -179,12 +191,10 @@ All remaining proto usage is at system boundaries, which is expected and appropr
 | View Filters | 0 | 0 | ✅ Complete |
 | Utility files | 0 | 0 | ✅ Complete |
 | History APIs | 0 | 0 | ✅ Complete |
-| LLM Prompt Generators | 0 | 0 | ✅ Complete |
-| LLM Request Generators | 0 | 0 | ✅ Complete |
-| Root Library (boundary) | 4 | 7 | Keep (boundary code) |
-| **Total** | **4** | **~7** | **All boundary code** |
-
-🎉 **All business logic is now protoless!** The remaining proto usage is exclusively at system boundaries (gRPC, persistence).
+| LLM Prompt Generators | 34 | 56 | Medium |
+| LLM Request Generators | 1 | 2 | Medium |
+| Root Library (boundary) | 4 | 7 | Keep |
+| **Total** | **~35** | **~65** | |
 
 ---
 
@@ -193,13 +203,13 @@ All remaining proto usage is at system boundaries, which is expected and appropr
 ### Code Quality
 - [x] Zero proto imports in `/ai/`
 - [x] Zero proto imports in `/library/actions/impl/command/`
-- [x] Zero proto imports in `/library/actions/availability/`
-- [x] Zero proto imports in `/library/util/command_choice_helpers/`
+- [ ] Zero proto imports in `/library/actions/availability/` (2 files use Hostility)
+- [ ] Zero proto imports in `/library/util/command_choice_helpers/` (1 file uses Hostility)
 - [x] Zero proto imports in `/library/actions/impl/action/`
 - [x] Zero proto imports in `/library/util/view_filters/` (except BattleFilter boundary code)
-- [x] Zero proto imports in `/library/util/` (except view filters)
+- [ ] Zero proto imports in `/library/util/` (FactionUtils uses Hostility)
 - [x] Zero proto imports in `/service/new_game_creation/` (except input GameParameters)
-- [x] Zero proto imports in `/library/actions/llm_prompt_generators/`
+- [ ] Zero proto imports in `/library/actions/llm_prompt_generators/` (4 files)
 - [x] Zero proto imports in `/library/actions/llm_request_generators/`
 
 ### Architecture
@@ -213,72 +223,78 @@ All remaining proto usage is at system boundaries, which is expected and appropr
 - [x] All view filters return Scala types
 - [x] NewGameCreation uses Scala types
 - [x] PersistedHistory accepts Scala types for new games
-- [x] LLM layer uses Scala types
-- [x] No "proto creep" into business logic
-
-✅ **All success criteria met!**
+- [ ] LLM layer uses Scala types (4 files remaining)
+- [ ] Hostility enum migrated to Scala (4 files remaining)
+- [ ] No "proto creep" into business logic
 
 ---
 
 ## Open Questions
 
-1. ~~**LLM Prompt Generators**: Should these accept Scala types directly, or is it acceptable to have proto usage here since they're generating text (not core game logic)?~~ **Resolved**: All LLM prompt generators now use Scala `LlmRequestT` types directly (PR #5429).
+1. **LLM Prompt Generators**: Should these accept Scala types directly, or is it acceptable to have proto usage here since they're generating text (not core game logic)?
 
 2. ~~**GameStateViewDiffer**: This works with view protos for client updates. Should it remain proto-based since it's generating client-facing data?~~ **Resolved**: GameStateViewDiffer now uses Scala types internally (`GameStateViewDiff`, `ProvinceViewDiff`, etc.) and converts to proto at the boundary in `ActionResultFilter`.
 
-3. **History Serialization**: Keep proto for persistence (good for schema evolution) or consider alternatives? **Decision**: Keep proto for persistence - it's appropriate for disk serialization and schema evolution.
+3. **History Serialization**: Keep proto for persistence (good for schema evolution) or consider alternatives?
 
 ---
 
 ## Proto Import Inventory (Detailed)
 
-**Current: ~7 proto imports across 4 files** (as of 2026-01-18) - all boundary code
+**Current: 13 files with direct proto imports in library/** (as of 2026-01-18)
+
+The `bazel query` command reports 167 proto dependencies, but this includes transitive dependencies. The actual files with direct proto imports are listed below.
+
+### Files with Proto Imports
+
+```bash
+# Verified with:
+grep -rl "import net.eagle0.eagle\.\(internal\|common\|api\|views\)\.\|import net.eagle0.shardok\.\|import net.eagle0.common.hostility" \
+  src/main/scala/net/eagle0/eagle/library/ --include="*.scala"
+```
+
+### Boundary Code (Keep Proto) - 5 files
+
+| File | Proto Imports | Notes |
+|------|---------------|-------|
+| `GameHistory.scala` | `ShardokActionResultView`, `ShardokAvailableCommands`, `ShardokActionResult` | Shardok integration boundary |
+| `Engine.scala` | `ActionResultView` | Returns proto for client |
+| `EngineImpl.scala` | `ActionResultView` | Returns proto for client |
+| `ActionResultFilter.scala` | `ActionResultTypeProto`, `ActionResultView`, `GameStateViewDiffProto` | View conversion boundary |
+| `BattleFilter.scala` | `Hostility` | Battle view boundary |
+
+### Hostility Proto - 4 files (Phase 8b)
+
+| File | Proto Imports | Notes |
+|------|---------------|-------|
+| `AvailableAttackDecisionCommandFactory.scala` | `Hostility` | Attack decision logic |
+| `AvailableFreeForAllDecisionCommandFactory.scala` | `Hostility` | FFA decision logic |
+| `AttackDecisionCommandChooser.scala` | `Hostility` | AI decision logic |
+| `FactionUtils.scala` | `Hostility` | Utility function |
+
+### LLM Prompt Generators - 4 files (Phase 8)
+
+| File | Proto Imports | Notes |
+|------|---------------|-------|
+| `BattalionDescriptions.scala` | `BattalionTypeId`, `Battalion`, `BattalionView` | Battalion text |
+| `ChronicleEventTextGenerator.scala` | `EventForChronicle.*` | Chronicle text |
+| `GeneratorUtilities.scala` | `Date` | Date formatting |
+| `QuestEndedGeneratorUtilities.scala` | `BattalionTypeId`, `UnaffiliatedHeroQuest.*` | Quest text |
 
 ### Summary by Directory
 
-| Directory | Files | Imports | Status |
-|-----------|-------|---------|--------|
-| `ai/` | 0 | 0 | ✅ Clean |
-| `actions/availability/` | 0 | 0 | ✅ Clean |
-| `actions/impl/action/` | 0 | 0 | ✅ Clean |
-| `actions/impl/command/` | 0 | 0 | ✅ Clean |
-| `actions/llm_prompt_generators/` | 0 | 0 | ✅ Clean |
-| `actions/llm_request_generators/` | 0 | 0 | ✅ Clean |
-| `util/command_choice_helpers/` | 0 | 0 | ✅ Clean |
-| `util/view_filters/` | 0 | 0 | ✅ Clean (except boundary) |
-| `util/` (other) | 0 | 0 | ✅ Clean |
-| Root (`library/`) | 4 | 7 | Boundary code (expected) |
-
-### util/view_filters/ (0 imports, except boundary)
-
-| File | Import | Notes |
-|------|--------|-------|
-| `GameStateViewFilter.scala` | ✅ **0** | Returns Scala `GameStateView`, converts at edge |
-| `GameStateViewDiffer.scala` | ✅ **0** | Uses Scala diff types, converts at edge |
-| `BattleFilter.scala` | 1 | Battle view boundary (keep proto) |
-
-### util/ other files ✅ Complete
-
-| File | Imports | Notes |
-|------|---------|-------|
-| `MapGenerator.scala` | ✅ **0** | Returns Scala types (PR #5373) |
-
-### Root library/ (7 imports, 4 files)
-
-| File | Imports | Notes |
-|------|---------|-------|
-| `ActionResultFilter.scala` | 3 | Action result filtering (boundary, uses Scala types internally) |
-| `Engine.scala` | 1 | Trait interface (returns `ActionResultView` proto for client) |
-| `EngineImpl.scala` | 1 | Returns proto for persistence (boundary) |
-| `ActionWithResultingState.scala` | 2 | Stores both proto and Scala (boundary for persistence) |
-
-### actions/llm_prompt_generators/ ✅ Complete (0 imports)
-
-All 34 files now use Scala `LlmRequestT` types (e.g., `LlmRequestT.DivineMessage`, `LlmRequestT.AllianceOfferMessage`). Converted in PR #5429.
-
-### actions/llm_request_generators/ ✅ Complete (0 imports)
-
-All LLM request generators now use Scala types. The `LlmRequestT` enum provides all request types, and `Status` sealed trait provides diplomacy offer statuses. Converted in PRs #5419-#5428.
+| Directory | Files with Proto | Status |
+|-----------|------------------|--------|
+| `ai/` | 0 | ✅ Clean |
+| `actions/availability/` | 2 | ⏳ Hostility proto |
+| `actions/impl/action/` | 0 | ✅ Clean |
+| `actions/impl/command/` | 0 | ✅ Clean |
+| `actions/llm_prompt_generators/` | 4 | ⏳ LLM types |
+| `util/command_choice_helpers/` | 1 | ⏳ Hostility proto |
+| `util/view_filters/` | 1 | Keep (boundary) |
+| `util/faction_utils/` | 1 | ⏳ Hostility proto |
+| Root (`library/`) | 4 | Keep (boundary) |
+| **Total** | **13** | |
 
 ---
 

scripts/build_deps_baseline.txt

@@ -0,0 +1,3 @@
+# BUILD dependency baseline - updated Sun Jan 18 15:45:56 PST 2026
+# Do not increase these numbers - only decrease!
+library_proto_deps=167

scripts/check_build_deps.sh

@@ -0,0 +1,158 @@
+#!/bin/bash
+# Check BUILD.bazel dependency constraints
+# This script enforces architectural boundaries in the codebase.
+#
+# Usage:
+#   ./scripts/check_build_deps.sh           # Check all rules
+#   ./scripts/check_build_deps.sh --ci      # CI mode (fail on any violation)
+#   ./scripts/check_build_deps.sh --count   # Just count current violations (for tracking progress)
+#   ./scripts/check_build_deps.sh --strict  # Fail if proto deps in library/ exceed baseline
+#
+# The baseline for proto deps is stored in scripts/build_deps_baseline.txt
+# Update it with: ./scripts/check_build_deps.sh --update-baseline
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+BASELINE_FILE="$SCRIPT_DIR/build_deps_baseline.txt"
+cd "$REPO_ROOT"
+
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m' # No Color
+
+MODE="${1:-check}"
+EXIT_CODE=0
+
+# Get baseline proto count (default to a high number if no baseline exists)
+get_baseline() {
+    if [ -f "$BASELINE_FILE" ]; then
+        grep "^library_proto_deps=" "$BASELINE_FILE" | cut -d= -f2
+    else
+        echo "999999"  # No baseline = don't fail
+    fi
+}
+
+# Rule 1: src/main should not depend on src/test
+check_main_depends_on_test() {
+    echo -e "${YELLOW}Checking: src/main should not depend on src/test...${NC}"
+
+    violations=$(bazel query 'deps(//src/main/...) intersect //src/test/...' 2>/dev/null || true)
+
+    if [ -n "$violations" ]; then
+        echo -e "${RED}VIOLATION: src/main depends on src/test:${NC}"
+        echo "$violations"
+        return 1
+    else
+        echo -e "${GREEN}✓ No violations${NC}"
+        return 0
+    fi
+}
+
+# Rule 2: library/ should not depend on src/main/protobuf
+# Note: This rule is aspirational - there are currently many violations as part of ongoing deproto effort
+check_library_depends_on_proto() {
+    echo -e "${YELLOW}Checking: library/ should not depend on src/main/protobuf...${NC}"
+
+    violations=$(bazel query 'deps(//src/main/scala/net/eagle0/eagle/library/...) intersect //src/main/protobuf/...' 2>/dev/null || true)
+    count=$(echo "$violations" | grep -c "^//" || echo "0")
+
+    if [ "$count" -gt 0 ]; then
+        echo -e "${YELLOW}Found $count proto dependencies in library/ (deproto in progress)${NC}"
+        if [ "$MODE" == "--count" ]; then
+            echo "$violations" | head -20
+            if [ "$count" -gt 20 ]; then
+                echo "... and $((count - 20)) more"
+            fi
+        fi
+        # Don't fail on this rule yet - it's aspirational
+        return 0
+    else
+        echo -e "${GREEN}✓ No proto dependencies in library/${NC}"
+        return 0
+    fi
+}
+
+# Count proto deps for tracking deproto progress
+count_proto_deps() {
+    echo -e "${YELLOW}=== Proto dependency counts ===${NC}"
+
+    library_count=$(bazel query 'deps(//src/main/scala/net/eagle0/eagle/library/...) intersect //src/main/protobuf/...' 2>/dev/null | grep -c "^//" || echo "0")
+    echo "library/: $library_count proto dependencies"
+
+    baseline=$(get_baseline)
+    if [ "$baseline" != "999999" ]; then
+        echo "baseline: $baseline"
+        if [ "$library_count" -lt "$baseline" ]; then
+            echo -e "${GREEN}↓ Reduced by $((baseline - library_count)) from baseline${NC}"
+        elif [ "$library_count" -gt "$baseline" ]; then
+            echo -e "${RED}↑ Increased by $((library_count - baseline)) from baseline${NC}"
+        fi
+    fi
+}
+
+# Check if proto deps exceed baseline (for strict mode)
+check_proto_baseline() {
+    library_count=$(bazel query 'deps(//src/main/scala/net/eagle0/eagle/library/...) intersect //src/main/protobuf/...' 2>/dev/null | grep -c "^//" || echo "0")
+    baseline=$(get_baseline)
+
+    echo -e "${YELLOW}Checking: proto deps in library/ should not exceed baseline...${NC}"
+    echo "Current: $library_count, Baseline: $baseline"
+
+    if [ "$library_count" -gt "$baseline" ]; then
+        echo -e "${RED}VIOLATION: Proto dependencies increased from $baseline to $library_count${NC}"
+        echo "Run './scripts/check_build_deps.sh --count' to see which protos are used"
+        return 1
+    else
+        echo -e "${GREEN}✓ Proto deps at or below baseline${NC}"
+        return 0
+    fi
+}
+
+# Update baseline file
+update_baseline() {
+    library_count=$(bazel query 'deps(//src/main/scala/net/eagle0/eagle/library/...) intersect //src/main/protobuf/...' 2>/dev/null | grep -c "^//" || echo "0")
+
+    echo "# BUILD dependency baseline - updated $(date)" > "$BASELINE_FILE"
+    echo "# Do not increase these numbers - only decrease!" >> "$BASELINE_FILE"
+    echo "library_proto_deps=$library_count" >> "$BASELINE_FILE"
+
+    echo -e "${GREEN}Updated baseline: library_proto_deps=$library_count${NC}"
+}
+
+echo "=== BUILD.bazel Dependency Check ==="
+echo ""
+
+case "$MODE" in
+    --count)
+        count_proto_deps
+        ;;
+    --ci)
+        check_main_depends_on_test || EXIT_CODE=1
+        check_library_depends_on_proto || EXIT_CODE=1
+        ;;
+    --strict)
+        check_main_depends_on_test || EXIT_CODE=1
+        check_proto_baseline || EXIT_CODE=1
+        ;;
+    --update-baseline)
+        update_baseline
+        ;;
+    *)
+        check_main_depends_on_test || EXIT_CODE=1
+        check_library_depends_on_proto
+        echo ""
+        count_proto_deps
+        ;;
+esac
+
+echo ""
+if [ $EXIT_CODE -eq 0 ]; then
+    echo -e "${GREEN}=== All checks passed ===${NC}"
+else
+    echo -e "${RED}=== Some checks failed ===${NC}"
+fi
+
+exit $EXIT_CODE