refactor: replace Bloop with Bazel BSP for IDE support

Replace deprecated Bloop integration with modern Bazel BSP for Metals IDE support.

Changes:
- Remove scala_bloop.bzl and tools/deploy.py (deprecated Bloop implementation)
- Remove blooplib target (used only for Bloop, caused CI failures)
- Remove CI Bloop check (replaced by Smoketests job)
- Add .bazelproject to configure BSP target selection
- Fix MODULE.bazel: use standard @rules_python for BSP compatibility
- Fix generate.bzl: remove allow_single_file from fir_library generator
- Fix chisel_test: use @bazel-orfs label for external dependency compatibility
- Update README with complete BSP setup instructions
- Add .bsp/ and .bazelbsp/ to .gitignore

Bazel BSP provides direct integration with Bazel, better accuracy, and active
community support.

Refs: http://scalameta.org/metals/docs/build-tools/bazel/

Author: MrAMS

.bazelproject

@@ -0,0 +1,12 @@
+targets:
+    //chisel:all
+    //sby:all
+
+allow_manual_targets_sync: false
+
+derive_targets_from_directories: false
+
+enabled_rules:
+    rules_scala
+    rules_java
+    rules_jvm

.github/workflows/ci.yml

@@ -29,26 +29,6 @@ jobs:
         run: |
           buildifier -lint warn -r .
 
-  bloop:
-    name: Check Bloop
-    runs-on: ubuntu-22.04
-    env:
-      DEBIAN_FRONTEND: "noninteractive"
-    steps:
-      - name: Checkout bazel-orfs
-        uses: actions/checkout@v4
-
-      - name: Setup Bazel
-        uses: bazel-contrib/setup-bazel@0.15.0
-        with:
-          bazelisk-cache: true
-          disk-cache: ${{ github.workflow }}-${{ github.job }}
-          repository-cache: true
-
-      - name: Run Bloop
-        run: |
-          bazel run :bloop
-
   test-make-target:
     name: ${{ matrix.STAGE_TARGET }}
     runs-on: ubuntu-22.04

.gitignore

@@ -8,3 +8,6 @@ node_modules/
 build.profile
 .bloop/
 external
+
+.bsp/
+.bazelbsp/

BUILD

@@ -4,12 +4,9 @@ load("@aspect_rules_js//js:defs.bzl", "js_binary")
 #
 # load("@bazel-orfs//tools/pin:pin.bzl", "pin_data")
 load("@bazel-orfs//toolchains/scala:chisel.bzl", "chisel_library")
-
-# Temporarily disabled during BCR rules_scala migration
-# load("@bazel-orfs//toolchains/scala:scala_bloop.bzl", "scala_bloop")
-load("@bazel_orfs_rules_python//python:defs.bzl", "py_binary")
-load("@bazel_orfs_rules_python//python:pip.bzl", "compile_pip_requirements")
 load("@npm//:defs.bzl", "npm_link_all_packages")
+load("@rules_python//python:defs.bzl", "py_binary")
+load("@rules_python//python:pip.bzl", "compile_pip_requirements")
 load("@rules_shell//shell:sh_binary.bzl", "sh_binary")
 
 # Reenable when we add test back in
@@ -545,21 +542,3 @@ sh_binary(
 #     tags = ["manual"],
 # )
 
-# This library lists all the scala files we will be editing in vscode via bloop
-chisel_library(
-    name = "blooplib",
-    srcs = [
-        "//chisel:chiselfiles",
-        "//sby:chiselfiles",
-        "//toolchains/scala:chiselfiles",
-    ],
-    deps = [
-        "@maven//:org_scalatest_scalatest_2_13",
-    ],
-)
-
-# Set up bloop (temporarily disabled during migration to BCR rules_scala)
-# scala_bloop(
-#     name = "bloop",
-#     src = "blooplib",
-# )

MODULE.bazel

@@ -67,20 +67,18 @@ load_json_file(
 bazel_dep(
     name = "rules_python",
     version = "1.6.3",
-    # reduce namespace collisions by prefixing with bazel_orfs
-    repo_name = "bazel_orfs_rules_python",
 )
 
 python = use_extension(
-    "@bazel_orfs_rules_python//python/extensions:python.bzl",
+    "@rules_python//python/extensions:python.bzl",
     "python",
 )
 python.toolchain(
     ignore_root_user_error = True,
     python_version = "3.13",
 )
 
-pip = use_extension("@bazel_orfs_rules_python//python/extensions:pip.bzl", "pip")
+pip = use_extension("@rules_python//python/extensions:pip.bzl", "pip")
 pip.parse(
     hub_name = "bazel-orfs-pip",
     python_version = "3.13",

generate.bzl

@@ -8,7 +8,6 @@ def _fir_library_impl(ctx):
     fir = ctx.actions.declare_file(ctx.attr.name + ".fir")
 
     args = ctx.actions.args()
-    args.add("-jar", ctx.file.generator)
     args.add_all([ctx.expand_location(opt, ctx.attr.data) for opt in ctx.attr.opts])
     args.add("-o", fir)
     ctx.actions.run(
@@ -39,7 +38,6 @@ fir_library = rule(
             allow_files = True,
         ),
         "generator": attr.label(
-            allow_single_file = True,
             cfg = "exec",
             executable = True,
             mandatory = True,

pythonwrapper/BUILD

@@ -1,4 +1,4 @@
-load("@bazel_orfs_rules_python//python:defs.bzl", "py_binary")
+load("@rules_python//python:defs.bzl", "py_binary")
 
 # FIXME emulate python3 and get venv we need from within orfs make
 py_binary(

toolchains/scala/README.md

@@ -9,7 +9,6 @@ The project uses **BCR rules_scala 7.1.5** from Bazel Central Registry as the un
 - Automatically includes Chisel 7.2.0 and its dependencies
 - Pre-configures Scala compiler options for Chisel
 - Sets up Verilator and firtool for hardware simulation (tests only)
-- Maintains API compatibility with existing BUILD files
 
 ## Usage
 
@@ -80,51 +79,68 @@ The `chisel_test` rule includes workarounds for BCR verilator compatibility:
 2. **Path resolution**: Automatically sets `VERILATOR_ROOT`, `VERILATOR_BIN`, and `PATH`
 3. **Forward compatibility**: Workarounds are conditional and will automatically disable when BCR verilator is fixed
 
-These workarounds are based on previous fixes (commits 0a3c114, c58bf7d) and ensure tests work without manual configuration.
+## IDE Support with Bazel BSP
 
-## Migration from Custom Toolchain
+This project uses [Bazel BSP](https://github.com/JetBrains/bazel-bsp) (Build Server Protocol) for IDE integration with Metals.
 
-This project was migrated from a custom Scala toolchain (~1500 lines) to BCR rules_scala (~250 lines of wrappers) in early 2025. The Chisel API remained unchanged, requiring no modifications to BUILD files.
+### Quick Setup
 
-### Benefits of BCR Migration
+1. **Install Bazel BSP**:
+   ```bash
+   cs install bsp
+   ```
 
-- **Reduced maintenance**: No custom toolchain to maintain
-- **Standard compliance**: Uses Bazel community standard
-- **Easy upgrades**: Can upgrade rules_scala independently
-- **Community support**: Can get help from wider Bazel community
+2. **Initialize BSP**:
+   ```bash
+   cd /path/to/bazel-orfs-local
+   bsp
+   ```
 
-### What Changed
+3. **Configure targets** (`.bazelproject` in project root):
+   ```
+   targets:
+       //:blooplib
+       //chisel:all
+       //sby:all
 
-**Deleted**:
-- Custom Scala toolchain implementation (`impl/`, `args/`, `tools/`, etc.)
-- Custom `scala_library`, `scala_binary` rule definitions
+   allow_manual_targets_sync: false
+   derive_targets_from_directories: false
 
-**Preserved**:
-- Chisel wrapper API (`chisel_*` rules)
-- All BUILD files using Chisel rules
+   enabled_rules:
+       rules_scala
+       rules_java
+       rules_jvm
+   ```
 
-**Modified**:
-- `MODULE.bazel`: Uses BCR rules_scala 7.1.5
-- `toolchains/scala/chisel.bzl`: Simplified to thin wrappers
+4. **Build project first**:
+   ```bash
+   bazel build //chisel:codegenlib //chisel:applicationlib
+   ```
 
-## Bloop Integration (Disabled)
+5. **Open in VSCode** and Metals will auto-connect to BSP
 
-The bloop integration for IDE support is temporarily disabled during the BCR migration:
+### Troubleshooting
 
-```python
-# Temporarily disabled in BUILD file
-# load("@bazel-orfs//toolchains/scala:scala_bloop.bzl", "scala_bloop")
-# scala_bloop(name = "bloop", src = "blooplib")
-```
+**No targets found**:
+- Verify `.bazelproject` exists in project root
+- Check targets: `bazel query "//chisel:all"`
+- Rebuild BSP index: VSCode → "Metals: Import Build"
+
+**Metals doesn't connect**:
+- Ensure `bsp` is in PATH: `which bsp`
+- Check `.bsp/bazelbsp.json` exists
+- Restart: VSCode → "Metals: Restart Build Server"
 
-To re-enable in the future, the `scala_bloop` rule needs to be updated to work with BCR rules_scala.
+**No IntelliSense**:
+- Wait for initial indexing (check status bar)
+- Verify build succeeds: `bazel build //chisel:codegenlib`
+- Check logs: VSCode → Output → Metals
 
-## Files
+### Resources
 
-- **chisel.bzl**: Main implementation of `chisel_binary`, `chisel_library`, `chisel_test`
-- **scala_bloop.bzl**: Bloop integration (currently disabled)
-- **BUILD.bazel**: Example usage (empty after migration)
-- **README.md**: This file
+- [Metals Bazel Documentation](http://scalameta.org/metals/docs/build-tools/bazel/)
+- [Bazel BSP Server](https://github.com/JetBrains/bazel-bsp)
+- [BSP Protocol Specification](https://build-server-protocol.github.io/)
 
 ## See Also
 

toolchains/scala/chisel.bzl

@@ -235,7 +235,7 @@ def chisel_test(name, **kwargs):
         "@circt//:bin/firtool",
         "@verilator//:bin/verilator",
         "@verilator//:verilator_includes",
-        "//toolchains/verilator:verilator_includer",
+        "@bazel-orfs//toolchains/verilator:verilator_includer",
     ] + kwargs.pop("data", [])
 
     # Create the underlying scala_test target