From c888d4806b25a3546a499d7efb881acec5a48429 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Tue, 14 Jul 2026 09:34:22 -0700
Subject: [PATCH 01/21] feat(js_run_binary): add support for path mapping

This change adds support for path mapping in `js_run_binary` by updating it to
use the new `--bazel-bindir` flag instead of setting the `BAZEL_BINDIR`
environment variable. The only mechanism Bazel provides for determining
path-mapped paths is by adding inputs directly to an `Args` object from
`ctx.actions.args()`. We can now compute the output Bazel bin directory that
way using a special case added to `run_binary()` for this purpose in
https://github.com/bazel-contrib/bazel-lib/pull/1269.

The `js_run_binary` macro currently sets several other problematic environment
variables: BAZEL_BUILD_FILE_PATH, BAZEL_COMPILATION_MODE, BAZEL_TARGET_CPU,
BAZEL_TARGET, and BAZEL_WORKSPACE. These are determined by evaluating Make
variables, and `run_binary` conservatively assumes that path mapping is not
safe if any location or Make variable expansion occurs. This change deprecates
these variables and adds a `set_legacy_environment_variables` parameter
(default `True`) so they can be disabled without a breaking change, ahead of
flipping the default in a future release. To enable path mapping on a
particular `js_run_binary` target, make sure to set this parameter to `False`.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
---
 js/private/js_run_binary.bzl | 35 +++++++++++++++++++++++------------
 1 file changed, 23 insertions(+), 12 deletions(-)

diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index 538c5a1214..4fe5022346 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -45,6 +45,7 @@ def js_run_binary(
         patch_node_fs = True,
         allow_execroot_entry_point_with_no_copy_data_to_bin = False,
         use_default_shell_env = False,
+        set_legacy_environment_variables = True,
         **kwargs):
     """Wrapper around @bazel_lib `run_binary` that adds convenience attributes for using a `js_binary` tool.
 
@@ -53,16 +54,16 @@ def js_run_binary(
     The following environment variables are made available to the Node.js runtime based on available Bazel [Make variables](https://bazel.build/reference/be/make-variables#predefined_variables):
 
     * BAZEL_BINDIR: the bazel bin directory; equivalent to the `$(BINDIR)` Make variable of the `js_run_binary` target
-    * BAZEL_COMPILATION_MODE: One of `fastbuild`, `dbg`, or `opt` as set by [`--compilation_mode`](https://bazel.build/docs/user-manual#compilation-mode); equivalent to `$(COMPILATION_MODE)` Make variable of the `js_run_binary` target
-    * BAZEL_TARGET_CPU: the target cpu architecture; equivalent to `$(TARGET_CPU)` Make variable of the `js_run_binary` target
+    * BAZEL_TARGET_CPU (legacy; see `set_legacy_environment_variables`): the target cpu architecture; equivalent to `$(TARGET_CPU)` Make variable of the `js_run_binary` target
+    * BAZEL_COMPILATION_MODE (legacy; see `set_legacy_environment_variables`): One of `fastbuild`, `dbg`, or `opt` as set by [`--compilation_mode`](https://bazel.build/docs/user-manual#compilation-mode); equivalent to `$(COMPILATION_MODE)` Make variable of the `js_run_binary` target
 
     The following environment variables are made available to the Node.js runtime based on the rule context:
 
-    * BAZEL_BUILD_FILE_PATH: the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
     * BAZEL_PACKAGE: the package of the bazel target being run; equivalent to `ctx.label.package` of the `js_run_binary` target's rule context
     * BAZEL_TARGET_NAME: the full label of the bazel target being run; a stringified version of `ctx.label` of the `js_run_binary` target's rule context
-    * BAZEL_TARGET: the name of the bazel target being run; equivalent to `ctx.label.name` of the  `js_run_binary` target's rule context
-    * BAZEL_WORKSPACE: the bazel repository name; equivalent to `ctx.workspace_name` of the `js_run_binary` target's rule context
+    * BAZEL_BUILD_FILE_PATH (legacy; see `set_legacy_environment_variables`): the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
+    * BAZEL_TARGET (legacy; see `set_legacy_environment_variables`): the name of the bazel target being run; equivalent to `ctx.label.name` of the  `js_run_binary` target's rule context
+    * BAZEL_WORKSPACE (legacy; see `set_legacy_environment_variables`): the bazel repository name; equivalent to `ctx.workspace_name` of the `js_run_binary` target's rule context
 
     Args:
         name: Target name
@@ -253,6 +254,13 @@ def js_run_binary(
 
             Refer to https://bazel.build/rules/lib/builtins/actions#run for more details.
 
+        set_legacy_environment_variables: Whether to set the legacy `BAZEL_BUILD_FILE_PATH`,
+            `BAZEL_COMPILATION_MODE`, `BAZEL_TARGET_CPU`, `BAZEL_TARGET` and `BAZEL_WORKSPACE`
+            environment variables.
+
+            These variables are deprecated and setting them will default to False in a future
+            release. Set this to False to opt out now.
+
         **kwargs: Additional arguments
     """
 
@@ -298,16 +306,19 @@ def js_run_binary(
 
     # Automatically add common and useful make variables to the environment for js_run_binary build targets
     fixed_env = {
-        "BAZEL_BINDIR": "$(BINDIR)",
-        "BAZEL_BUILD_FILE_PATH": "$(BUILD_FILE_PATH)",
-        "BAZEL_COMPILATION_MODE": "$(COMPILATION_MODE)",
         "BAZEL_PACKAGE": native.package_name(),
-        "BAZEL_TARGET_CPU": "$(TARGET_CPU)",
         "BAZEL_TARGET_NAME": name,
-        "BAZEL_TARGET": "$(TARGET)",
-        "BAZEL_WORKSPACE": "$(WORKSPACE)",
     }
 
+    # These environment variables are deprecated and will default to not being set in a future
+    # release; see the `set_legacy_environment_variables` docstring.
+    if set_legacy_environment_variables:
+        fixed_env["BAZEL_BUILD_FILE_PATH"] = "$(BUILD_FILE_PATH)"
+        fixed_env["BAZEL_COMPILATION_MODE"] = "$(COMPILATION_MODE)"
+        fixed_env["BAZEL_TARGET_CPU"] = "$(TARGET_CPU)"
+        fixed_env["BAZEL_TARGET"] = "$(TARGET)"
+        fixed_env["BAZEL_WORKSPACE"] = "$(WORKSPACE)"
+
     # Configure working directory to `chdir` is set
     if chdir != None:
         normalized_chdir = "." if chdir == "" else chdir
@@ -422,7 +433,7 @@ See https://github.com/aspect-build/rules_js/tree/main/docs#using-binaries-publi
         srcs = srcs + extra_srcs + execroot_extra_srcs,
         outs = outs + extra_outs,
         out_dirs = out_dirs,
-        args = args,
+        args = ["--bazel-bindir", "$(BINDIR)"] + args,
         mnemonic = mnemonic,
         progress_message = progress_message,
         execution_requirements = execution_requirements,

From ab3e8da8ab49d99566c622c80d159ce2425f15e4 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Sat, 1 Aug 2026 15:55:35 -0700
Subject: [PATCH 02/21] Upgrade bazel_lib to 3.7.0

---
 MODULE.bazel | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/MODULE.bazel b/MODULE.bazel
index 2b47c33b29..16e891975b 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -19,7 +19,8 @@ bazel_dep(name = "rules_nodejs", version = "6.7.3")
 
 # Changes ensured by rules_js:
 # 3.2.2: https://github.com/bazel-contrib/bazel-lib/commit/cac2d7855949d1b222fa26888892fbbe1d31015d
-bazel_dep(name = "bazel_lib", version = "3.2.2")
+# 3.7.0: https://github.com/bazel-contrib/bazel-lib/commit/e5c0630270f70dd2c7b50471bb9c872781a55282
+bazel_dep(name = "bazel_lib", version = "3.7.0")
 
 # NB: LOWER BOUND on earliest BCR release of protobuf module, to avoid upgrading the root module by accident
 bazel_dep(name = "protobuf", version = "3.19.6")

From 1d5d563e92aa836d6ccc2e69b496e6447deabfde Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Sat, 1 Aug 2026 16:12:12 -0700
Subject: [PATCH 03/21] Added e2e test

---
 .../BUILD.bazel                               | 29 +++++++++++++++++++
 .../check.mjs                                 | 26 +++++++++++++++++
 e2e/path_mapping/test.sh                      | 28 ++++++++++++++++++
 3 files changed, 83 insertions(+)
 create mode 100644 e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
 create mode 100644 e2e/path_mapping/js_run_binary_path_mapping_check/check.mjs

diff --git a/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel b/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
new file mode 100644
index 0000000000..57bd6d4dbd
--- /dev/null
+++ b/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
@@ -0,0 +1,29 @@
+load("@aspect_rules_js//js:defs.bzl", "js_binary", "js_run_binary")
+load("@bazel_skylib//rules:build_test.bzl", "build_test")
+
+# Verifies that a js_run_binary target itself (as opposed to a custom rule
+# using js_run_binary_action, exercised by ../bindir_path_mapping_check)
+# supports Bazel's path mapping. This requires use_execroot_entry_point and
+# set_legacy_environment_variables to both be disabled, and args must avoid
+# Make variable and location expansion, since js_run_binary's underlying
+# run_binary only advertises path mapping support when none of that
+# expansion occurs.
+js_binary(
+    name = "check",
+    entry_point = "check.mjs",
+)
+
+js_run_binary(
+    name = "js_run_binary_path_mapping_check",
+    out_dirs = ["out"],
+    args = [package_name() + "/out"],
+    mnemonic = "JsRunBinaryPathMappingCheck",
+    tool = ":check",
+    use_execroot_entry_point = False,
+    set_legacy_environment_variables = False,
+)
+
+build_test(
+    name = "js_run_binary_path_mapping_check_test",
+    targets = [":js_run_binary_path_mapping_check"],
+)
diff --git a/e2e/path_mapping/js_run_binary_path_mapping_check/check.mjs b/e2e/path_mapping/js_run_binary_path_mapping_check/check.mjs
new file mode 100644
index 0000000000..9c7fffe3ec
--- /dev/null
+++ b/e2e/path_mapping/js_run_binary_path_mapping_check/check.mjs
@@ -0,0 +1,26 @@
+import { mkdirSync, writeFileSync } from 'fs'
+import { join } from 'path'
+
+const outDir = process.argv[2]
+if (!outDir) {
+    process.stderr.write('Usage: check.mjs <output-dir>\n')
+    process.exit(1)
+}
+
+const bindir = process.env.BAZEL_BINDIR
+if (bindir !== 'bazel-out/cfg/bin') {
+    process.stderr.write(
+        `Expected BAZEL_BINDIR to be "bazel-out/cfg/bin", got "${bindir}"\n`
+    )
+    process.exit(1)
+}
+
+const leaked = process.argv.filter((arg) => arg === '--bazel-bindir')
+if (leaked.length > 0) {
+    process.stderr.write(`--bazel-bindir flag leaked into argv: ${leaked}\n`)
+    process.exit(1)
+}
+
+mkdirSync(outDir, { recursive: true })
+writeFileSync(join(outDir, 'file1'), 'OK\n')
+writeFileSync(join(outDir, 'file2'), 'OK\n')
diff --git a/e2e/path_mapping/test.sh b/e2e/path_mapping/test.sh
index a7f6e782fe..aabf0a2d0f 100755
--- a/e2e/path_mapping/test.sh
+++ b/e2e/path_mapping/test.sh
@@ -47,3 +47,31 @@ if [ "$cache_hit" != "true" ]; then
 fi
 
 echo "PASS: action was cache-shared across -c fastbuild and -c opt"
+
+# Same proof as above, but exercising a plain js_run_binary target instead of
+# a custom rule built on js_run_binary_action.
+exec_log2="$scratch/exec_log2.json"
+
+bazel build -c fastbuild //js_run_binary_path_mapping_check \
+    --disk_cache="$disk_cache" \
+    --action_env="JS_RUN_BINARY_PATH_MAPPING_CHECK_INVALIDATE=$invalidate"
+
+bazel build -c opt //js_run_binary_path_mapping_check \
+    --disk_cache="$disk_cache" \
+    --action_env="JS_RUN_BINARY_PATH_MAPPING_CHECK_INVALIDATE=$invalidate" \
+    --execution_log_json_file="$exec_log2"
+
+matches2="$(jq -s '[.[] | select(.mnemonic == "JsRunBinaryPathMappingCheck")]' "$exec_log2")"
+count2="$(echo "$matches2" | jq 'length')"
+if [ "$count2" -eq 0 ]; then
+    echo "FAIL: no JsRunBinaryPathMappingCheck entry found in the -c opt execution log" >&2
+    exit 1
+fi
+
+cache_hit2="$(echo "$matches2" | jq -r '.[0].cacheHit')"
+if [ "$cache_hit2" != "true" ]; then
+    echo "FAIL: js_run_binary action was re-executed under -c opt (cacheHit=$cache_hit2); path mapping did not share the cache entry from -c fastbuild" >&2
+    exit 1
+fi
+
+echo "PASS: js_run_binary action was cache-shared across -c fastbuild and -c opt"

From fde0d204ef64acc4ee1251ab25b50c567c59c3eb Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Sat, 1 Aug 2026 16:19:18 -0700
Subject: [PATCH 04/21] Simplify some things

---
 .../js_run_binary_path_mapping_check/BUILD.bazel   | 14 +++++---------
 .../js_run_binary_path_mapping_check/check.mjs     | 13 +++++--------
 e2e/path_mapping/test.sh                           |  4 ++--
 3 files changed, 12 insertions(+), 19 deletions(-)

diff --git a/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel b/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
index 57bd6d4dbd..6580c3c22d 100644
--- a/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
+++ b/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
@@ -1,13 +1,9 @@
 load("@aspect_rules_js//js:defs.bzl", "js_binary", "js_run_binary")
 load("@bazel_skylib//rules:build_test.bzl", "build_test")
 
-# Verifies that a js_run_binary target itself (as opposed to a custom rule
-# using js_run_binary_action, exercised by ../bindir_path_mapping_check)
-# supports Bazel's path mapping. This requires use_execroot_entry_point and
-# set_legacy_environment_variables to both be disabled, and args must avoid
-# Make variable and location expansion, since js_run_binary's underlying
-# run_binary only advertises path mapping support when none of that
-# expansion occurs.
+# Verifies that a js_run_binary target supports path mapping. This requires
+# use_execroot_entry_point and set_legacy_environment_variables to both be
+# disabled, and args must avoid Make variable and location expansion.
 js_binary(
     name = "check",
     entry_point = "check.mjs",
@@ -15,8 +11,8 @@ js_binary(
 
 js_run_binary(
     name = "js_run_binary_path_mapping_check",
-    out_dirs = ["out"],
-    args = [package_name() + "/out"],
+    outs = ["out.txt"],
+    args = [package_name() + "/out.txt"],
     mnemonic = "JsRunBinaryPathMappingCheck",
     tool = ":check",
     use_execroot_entry_point = False,
diff --git a/e2e/path_mapping/js_run_binary_path_mapping_check/check.mjs b/e2e/path_mapping/js_run_binary_path_mapping_check/check.mjs
index 9c7fffe3ec..076912720f 100644
--- a/e2e/path_mapping/js_run_binary_path_mapping_check/check.mjs
+++ b/e2e/path_mapping/js_run_binary_path_mapping_check/check.mjs
@@ -1,9 +1,8 @@
-import { mkdirSync, writeFileSync } from 'fs'
-import { join } from 'path'
+import { writeFileSync } from 'fs'
 
-const outDir = process.argv[2]
-if (!outDir) {
-    process.stderr.write('Usage: check.mjs <output-dir>\n')
+const outFile = process.argv[2]
+if (!outFile) {
+    process.stderr.write('Usage: check.mjs <output-file>\n')
     process.exit(1)
 }
 
@@ -21,6 +20,4 @@ if (leaked.length > 0) {
     process.exit(1)
 }
 
-mkdirSync(outDir, { recursive: true })
-writeFileSync(join(outDir, 'file1'), 'OK\n')
-writeFileSync(join(outDir, 'file2'), 'OK\n')
+writeFileSync(outFile, 'OK\n')
diff --git a/e2e/path_mapping/test.sh b/e2e/path_mapping/test.sh
index aabf0a2d0f..ed18fdd8ea 100755
--- a/e2e/path_mapping/test.sh
+++ b/e2e/path_mapping/test.sh
@@ -48,8 +48,8 @@ fi
 
 echo "PASS: action was cache-shared across -c fastbuild and -c opt"
 
-# Same proof as above, but exercising a plain js_run_binary target instead of
-# a custom rule built on js_run_binary_action.
+# Same as above, but exercising a js_run_binary target instead of a custom rule
+# built on js_run_binary_action.
 exec_log2="$scratch/exec_log2.json"
 
 bazel build -c fastbuild //js_run_binary_path_mapping_check \

From 2daa7fac3a854c3b588b707516740f59e7eeb11b Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Sat, 1 Aug 2026 16:20:15 -0700
Subject: [PATCH 05/21] buildifier

---
 e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel b/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
index 6580c3c22d..8b0e84baf4 100644
--- a/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
+++ b/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
@@ -14,9 +14,9 @@ js_run_binary(
     outs = ["out.txt"],
     args = [package_name() + "/out.txt"],
     mnemonic = "JsRunBinaryPathMappingCheck",
+    set_legacy_environment_variables = False,
     tool = ":check",
     use_execroot_entry_point = False,
-    set_legacy_environment_variables = False,
 )
 
 build_test(

From e4affbee519c9f63da407980698c8469d5a43b9a Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Sat, 1 Aug 2026 16:22:27 -0700
Subject: [PATCH 06/21] Avoid re-ordering variables

---
 js/private/js_run_binary.bzl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index 4fe5022346..1facbfcd8f 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -54,8 +54,8 @@ def js_run_binary(
     The following environment variables are made available to the Node.js runtime based on available Bazel [Make variables](https://bazel.build/reference/be/make-variables#predefined_variables):
 
     * BAZEL_BINDIR: the bazel bin directory; equivalent to the `$(BINDIR)` Make variable of the `js_run_binary` target
-    * BAZEL_TARGET_CPU (legacy; see `set_legacy_environment_variables`): the target cpu architecture; equivalent to `$(TARGET_CPU)` Make variable of the `js_run_binary` target
     * BAZEL_COMPILATION_MODE (legacy; see `set_legacy_environment_variables`): One of `fastbuild`, `dbg`, or `opt` as set by [`--compilation_mode`](https://bazel.build/docs/user-manual#compilation-mode); equivalent to `$(COMPILATION_MODE)` Make variable of the `js_run_binary` target
+    * BAZEL_TARGET_CPU (legacy; see `set_legacy_environment_variables`): the target cpu architecture; equivalent to `$(TARGET_CPU)` Make variable of the `js_run_binary` target
 
     The following environment variables are made available to the Node.js runtime based on the rule context:
 

From 6721f5702c195ed7687a487584893857e3a4395b Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 14:19:50 -0700
Subject: [PATCH 07/21] Compute some of these variables inside the macro

---
 js/private/js_run_binary.bzl | 43 ++++++++++++++++++++++++++++--------
 1 file changed, 34 insertions(+), 9 deletions(-)

diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index 1facbfcd8f..7ee31b9be2 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -17,6 +17,24 @@ load(":js_helpers.bzl", _envs_for_log_level = "envs_for_log_level")
 load(":js_info_files.bzl", _js_info_files = "js_info_files")
 load(":js_library.bzl", _js_library = "js_library")
 
+def _build_file_path():
+    """Returns the package-relative path to the current package's BUILD file.
+
+    Equivalent to `ctx.build_file_path`, but computed at macro-evaluation time since macros have
+    no `ctx`. The build file's name isn't known in advance (`BUILD` or `BUILD.bazel`), so this
+    uses `glob()` to detect it; if both are present, `BUILD.bazel` wins, matching Bazel's own
+    precedence.
+    """
+    matches = native.glob(["BUILD.bazel", "BUILD"], allow_empty = True)
+    if "BUILD.bazel" in matches:
+        build_file_name = "BUILD.bazel"
+    elif "BUILD" in matches:
+        build_file_name = "BUILD"
+    else:
+        fail("Could not find a BUILD or BUILD.bazel file in package '{}'".format(native.package_name()))
+    package = native.package_name()
+    return "{}/{}".format(package, build_file_name) if package else build_file_name
+
 def js_run_binary(
         name,
         tool,
@@ -61,9 +79,9 @@ def js_run_binary(
 
     * BAZEL_PACKAGE: the package of the bazel target being run; equivalent to `ctx.label.package` of the `js_run_binary` target's rule context
     * BAZEL_TARGET_NAME: the full label of the bazel target being run; a stringified version of `ctx.label` of the `js_run_binary` target's rule context
-    * BAZEL_BUILD_FILE_PATH (legacy; see `set_legacy_environment_variables`): the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
-    * BAZEL_TARGET (legacy; see `set_legacy_environment_variables`): the name of the bazel target being run; equivalent to `ctx.label.name` of the  `js_run_binary` target's rule context
-    * BAZEL_WORKSPACE (legacy; see `set_legacy_environment_variables`): the bazel repository name; equivalent to `ctx.workspace_name` of the `js_run_binary` target's rule context
+    * BAZEL_BUILD_FILE_PATH: the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
+    * BAZEL_TARGET: the name of the bazel target being run; equivalent to `ctx.label.name` of the  `js_run_binary` target's rule context
+    * BAZEL_WORKSPACE: the bazel repository name; equivalent to `ctx.workspace_name` of the `js_run_binary` target's rule context
 
     Args:
         name: Target name
@@ -254,9 +272,8 @@ def js_run_binary(
 
             Refer to https://bazel.build/rules/lib/builtins/actions#run for more details.
 
-        set_legacy_environment_variables: Whether to set the legacy `BAZEL_BUILD_FILE_PATH`,
-            `BAZEL_COMPILATION_MODE`, `BAZEL_TARGET_CPU`, `BAZEL_TARGET` and `BAZEL_WORKSPACE`
-            environment variables.
+        set_legacy_environment_variables: Whether to set the legacy `BAZEL_COMPILATION_MODE`
+            and `BAZEL_TARGET_CPU` environment variables.
 
             These variables are deprecated and setting them will default to False in a future
             release. Set this to False to opt out now.
@@ -305,19 +322,27 @@ def js_run_binary(
         extra_srcs.append(":{}".format(copy_to_bin_name))
 
     # Automatically add common and useful make variables to the environment for js_run_binary build targets
+    label = native.package_relative_label(name)
     fixed_env = {
+        "BAZEL_BUILD_FILE_PATH": _build_file_path(),
         "BAZEL_PACKAGE": native.package_name(),
         "BAZEL_TARGET_NAME": name,
+        "BAZEL_TARGET": "{}//{}:{}".format(
+            "@" + label.repo_name if label.repo_name else "",
+            label.package,
+            label.name,
+        ),
+        # This variable used to be derived from ctx.workspace_name and was the
+        # name from the WORKSPACE file, but with bzlmod it is always just
+        # "_main".
+        "BAZEL_WORKSPACE": "_main",
     }
 
     # These environment variables are deprecated and will default to not being set in a future
     # release; see the `set_legacy_environment_variables` docstring.
     if set_legacy_environment_variables:
-        fixed_env["BAZEL_BUILD_FILE_PATH"] = "$(BUILD_FILE_PATH)"
         fixed_env["BAZEL_COMPILATION_MODE"] = "$(COMPILATION_MODE)"
         fixed_env["BAZEL_TARGET_CPU"] = "$(TARGET_CPU)"
-        fixed_env["BAZEL_TARGET"] = "$(TARGET)"
-        fixed_env["BAZEL_WORKSPACE"] = "$(WORKSPACE)"
 
     # Configure working directory to `chdir` is set
     if chdir != None:

From 48a9dd6abb50da50c91c91ecb00ec47ef74ee1e3 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 14:23:16 -0700
Subject: [PATCH 08/21] Fix ordering

---
 js/private/js_run_binary.bzl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index 7ee31b9be2..9ae44e0b54 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -77,9 +77,9 @@ def js_run_binary(
 
     The following environment variables are made available to the Node.js runtime based on the rule context:
 
+    * BAZEL_BUILD_FILE_PATH: the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
     * BAZEL_PACKAGE: the package of the bazel target being run; equivalent to `ctx.label.package` of the `js_run_binary` target's rule context
     * BAZEL_TARGET_NAME: the full label of the bazel target being run; a stringified version of `ctx.label` of the `js_run_binary` target's rule context
-    * BAZEL_BUILD_FILE_PATH: the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
     * BAZEL_TARGET: the name of the bazel target being run; equivalent to `ctx.label.name` of the  `js_run_binary` target's rule context
     * BAZEL_WORKSPACE: the bazel repository name; equivalent to `ctx.workspace_name` of the `js_run_binary` target's rule context
 

From ab101ca1bfcbc2ff33906c9e7154fe144e697f9e Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 14:55:49 -0700
Subject: [PATCH 09/21] Add e2e tests for BAZEL_BUILD_FILE_PATH and
 BAZEL_TARGET across modules

Verify these js_run_binary env vars, now computed directly in the macro
instead of via Make-variable substitution, are correct when the
js_run_binary target lives in a module other than the main one.
---
 e2e/js_binary_workspace/BUILD.bazel           |  2 +
 e2e/js_binary_workspace/workspace/BUILD.bazel | 58 +++++++++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/e2e/js_binary_workspace/BUILD.bazel b/e2e/js_binary_workspace/BUILD.bazel
index 9d9ced94c9..c2f6f25103 100644
--- a/e2e/js_binary_workspace/BUILD.bazel
+++ b/e2e/js_binary_workspace/BUILD.bazel
@@ -45,6 +45,8 @@ build_test(
 test_suite(
     name = "external_tests",
     tests = [
+        "@workspace//:bazel_build_file_path_test",
+        "@workspace//:bazel_target_test",
         "@workspace//:js_binary_chdir_test",
         "@workspace//:js_test_chdir_test",
     ],
diff --git a/e2e/js_binary_workspace/workspace/BUILD.bazel b/e2e/js_binary_workspace/workspace/BUILD.bazel
index c9ada1d870..aa8389a3ab 100644
--- a/e2e/js_binary_workspace/workspace/BUILD.bazel
+++ b/e2e/js_binary_workspace/workspace/BUILD.bazel
@@ -16,6 +16,64 @@ js_run_binary(
     visibility = ["//visibility:public"],
 )
 
+# Verify that BAZEL_BUILD_FILE_PATH and BAZEL_TARGET, which js_run_binary now computes itself
+# instead of expanding via Make variables, are correct for a js_run_binary target that lives in
+# a module other than the main one (this "workspace" module is consumed as an external repo by
+# the root module in ../BUILD.bazel).
+js_run_binary(
+    name = "check_bazel_vars",
+    log_level = "debug",
+    silent_on_success = False,
+    stderr = "check_bazel_vars_stderr.txt",
+    tool = ":bin",
+    visibility = ["//visibility:public"],
+)
+
+write_file(
+    name = "assert_contains_sh",
+    out = "assert_contains.sh",
+    content = [
+        "#!/usr/bin/env bash",
+        "set -euo pipefail",
+        "file=$1",
+        "shift",
+        # Bazel's test runner may pass each whitespace-separated word of an `args` entry as its
+        # own argv item, so the expected substring is split across argv and rejoined here with
+        # single spaces rather than passed as one already-spaced string.
+        'expected="$*"',
+        "if ! grep -qF -- \"$expected\" \"$file\"; then",
+        "    echo \"expected '$file' to contain '$expected', but it did not. Contents:\" >&2",
+        "    cat \"$file\" >&2",
+        "    exit 1",
+        "fi",
+    ],
+)
+
+# Expect the canonical label of this js_run_binary target, prefixed with this module's canonical
+# repo name (not the root module's, and not aspect_rules_js's own).
+sh_test(
+    name = "bazel_target_test",
+    srcs = [":assert_contains.sh"],
+    args = [
+        "$(rootpath :check_bazel_vars_stderr.txt)",
+        "BAZEL_TARGET",
+        "@workspace+//:check_bazel_vars",
+    ],
+    data = [":check_bazel_vars_stderr.txt"],
+)
+
+# Expect the BUILD file path relative to this module's root, not the root module's.
+sh_test(
+    name = "bazel_build_file_path_test",
+    srcs = [":assert_contains.sh"],
+    args = [
+        "$(rootpath :check_bazel_vars_stderr.txt)",
+        "BAZEL_BUILD_FILE_PATH",
+        "BUILD.bazel",
+    ],
+    data = [":check_bazel_vars_stderr.txt"],
+)
+
 # Write the expected relative working directory beginning with bazel-out/
 genrule(
     name = "working_directory_expected",

From 3406fb50b89a07086a806da671c39d1242ead020 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 15:02:23 -0700
Subject: [PATCH 10/21] Shorten long comment

---
 e2e/js_binary_workspace/workspace/BUILD.bazel | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/e2e/js_binary_workspace/workspace/BUILD.bazel b/e2e/js_binary_workspace/workspace/BUILD.bazel
index aa8389a3ab..b0cba13473 100644
--- a/e2e/js_binary_workspace/workspace/BUILD.bazel
+++ b/e2e/js_binary_workspace/workspace/BUILD.bazel
@@ -16,10 +16,10 @@ js_run_binary(
     visibility = ["//visibility:public"],
 )
 
-# Verify that BAZEL_BUILD_FILE_PATH and BAZEL_TARGET, which js_run_binary now computes itself
-# instead of expanding via Make variables, are correct for a js_run_binary target that lives in
-# a module other than the main one (this "workspace" module is consumed as an external repo by
-# the root module in ../BUILD.bazel).
+# Verify that BAZEL_BUILD_FILE_PATH and BAZEL_TARGET are correct for a
+# js_run_binary target that lives in a module other than the main one (this
+# "workspace" module is consumed as an external repo by the root module in
+# ../BUILD.bazel).
 js_run_binary(
     name = "check_bazel_vars",
     log_level = "debug",

From b2211b6d84868b1a894327dd35f45f27e28cac0e Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 15:17:47 -0700
Subject: [PATCH 11/21] Fix bazel_target_test to work across Bazel versions

The expected BAZEL_TARGET value hardcoded the canonical repo name's
separator ("workspace+"), which differs across Bazel versions
("workspace~" on Bazel 7, "workspace+" on Bazel 9+), causing the test
to fail under Bazel 7.7.1. Derive it via repo_name() instead.
---
 e2e/js_binary_workspace/workspace/BUILD.bazel | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/e2e/js_binary_workspace/workspace/BUILD.bazel b/e2e/js_binary_workspace/workspace/BUILD.bazel
index b0cba13473..972a38673d 100644
--- a/e2e/js_binary_workspace/workspace/BUILD.bazel
+++ b/e2e/js_binary_workspace/workspace/BUILD.bazel
@@ -50,14 +50,16 @@ write_file(
 )
 
 # Expect the canonical label of this js_run_binary target, prefixed with this module's canonical
-# repo name (not the root module's, and not aspect_rules_js's own).
+# repo name (not the root module's, and not aspect_rules_js's own). The canonical name's
+# separator differs across Bazel versions ("workspace~" on Bazel 7, "workspace+" on Bazel 9), so
+# it's derived via repo_name() here rather than hardcoded.
 sh_test(
     name = "bazel_target_test",
     srcs = [":assert_contains.sh"],
     args = [
         "$(rootpath :check_bazel_vars_stderr.txt)",
         "BAZEL_TARGET",
-        "@workspace+//:check_bazel_vars",
+        "{}//:check_bazel_vars".format("@" + repo_name() if repo_name() else ""),
     ],
     data = [":check_bazel_vars_stderr.txt"],
 )

From d7aea7d5f8e5aad4597d1f8716f5fbdc8d3b7436 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 16:02:11 -0700
Subject: [PATCH 12/21] Revert to Make-variable expansion for the legacy
 js_run_binary env vars

---
 e2e/js_binary_workspace/BUILD.bazel           |  2 -
 e2e/js_binary_workspace/workspace/BUILD.bazel | 60 -------------------
 js/private/js_run_binary.bzl                  | 45 ++++----------
 3 files changed, 10 insertions(+), 97 deletions(-)

diff --git a/e2e/js_binary_workspace/BUILD.bazel b/e2e/js_binary_workspace/BUILD.bazel
index c2f6f25103..9d9ced94c9 100644
--- a/e2e/js_binary_workspace/BUILD.bazel
+++ b/e2e/js_binary_workspace/BUILD.bazel
@@ -45,8 +45,6 @@ build_test(
 test_suite(
     name = "external_tests",
     tests = [
-        "@workspace//:bazel_build_file_path_test",
-        "@workspace//:bazel_target_test",
         "@workspace//:js_binary_chdir_test",
         "@workspace//:js_test_chdir_test",
     ],
diff --git a/e2e/js_binary_workspace/workspace/BUILD.bazel b/e2e/js_binary_workspace/workspace/BUILD.bazel
index 972a38673d..c9ada1d870 100644
--- a/e2e/js_binary_workspace/workspace/BUILD.bazel
+++ b/e2e/js_binary_workspace/workspace/BUILD.bazel
@@ -16,66 +16,6 @@ js_run_binary(
     visibility = ["//visibility:public"],
 )
 
-# Verify that BAZEL_BUILD_FILE_PATH and BAZEL_TARGET are correct for a
-# js_run_binary target that lives in a module other than the main one (this
-# "workspace" module is consumed as an external repo by the root module in
-# ../BUILD.bazel).
-js_run_binary(
-    name = "check_bazel_vars",
-    log_level = "debug",
-    silent_on_success = False,
-    stderr = "check_bazel_vars_stderr.txt",
-    tool = ":bin",
-    visibility = ["//visibility:public"],
-)
-
-write_file(
-    name = "assert_contains_sh",
-    out = "assert_contains.sh",
-    content = [
-        "#!/usr/bin/env bash",
-        "set -euo pipefail",
-        "file=$1",
-        "shift",
-        # Bazel's test runner may pass each whitespace-separated word of an `args` entry as its
-        # own argv item, so the expected substring is split across argv and rejoined here with
-        # single spaces rather than passed as one already-spaced string.
-        'expected="$*"',
-        "if ! grep -qF -- \"$expected\" \"$file\"; then",
-        "    echo \"expected '$file' to contain '$expected', but it did not. Contents:\" >&2",
-        "    cat \"$file\" >&2",
-        "    exit 1",
-        "fi",
-    ],
-)
-
-# Expect the canonical label of this js_run_binary target, prefixed with this module's canonical
-# repo name (not the root module's, and not aspect_rules_js's own). The canonical name's
-# separator differs across Bazel versions ("workspace~" on Bazel 7, "workspace+" on Bazel 9), so
-# it's derived via repo_name() here rather than hardcoded.
-sh_test(
-    name = "bazel_target_test",
-    srcs = [":assert_contains.sh"],
-    args = [
-        "$(rootpath :check_bazel_vars_stderr.txt)",
-        "BAZEL_TARGET",
-        "{}//:check_bazel_vars".format("@" + repo_name() if repo_name() else ""),
-    ],
-    data = [":check_bazel_vars_stderr.txt"],
-)
-
-# Expect the BUILD file path relative to this module's root, not the root module's.
-sh_test(
-    name = "bazel_build_file_path_test",
-    srcs = [":assert_contains.sh"],
-    args = [
-        "$(rootpath :check_bazel_vars_stderr.txt)",
-        "BAZEL_BUILD_FILE_PATH",
-        "BUILD.bazel",
-    ],
-    data = [":check_bazel_vars_stderr.txt"],
-)
-
 # Write the expected relative working directory beginning with bazel-out/
 genrule(
     name = "working_directory_expected",
diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index 9ae44e0b54..4fe5022346 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -17,24 +17,6 @@ load(":js_helpers.bzl", _envs_for_log_level = "envs_for_log_level")
 load(":js_info_files.bzl", _js_info_files = "js_info_files")
 load(":js_library.bzl", _js_library = "js_library")
 
-def _build_file_path():
-    """Returns the package-relative path to the current package's BUILD file.
-
-    Equivalent to `ctx.build_file_path`, but computed at macro-evaluation time since macros have
-    no `ctx`. The build file's name isn't known in advance (`BUILD` or `BUILD.bazel`), so this
-    uses `glob()` to detect it; if both are present, `BUILD.bazel` wins, matching Bazel's own
-    precedence.
-    """
-    matches = native.glob(["BUILD.bazel", "BUILD"], allow_empty = True)
-    if "BUILD.bazel" in matches:
-        build_file_name = "BUILD.bazel"
-    elif "BUILD" in matches:
-        build_file_name = "BUILD"
-    else:
-        fail("Could not find a BUILD or BUILD.bazel file in package '{}'".format(native.package_name()))
-    package = native.package_name()
-    return "{}/{}".format(package, build_file_name) if package else build_file_name
-
 def js_run_binary(
         name,
         tool,
@@ -72,16 +54,16 @@ def js_run_binary(
     The following environment variables are made available to the Node.js runtime based on available Bazel [Make variables](https://bazel.build/reference/be/make-variables#predefined_variables):
 
     * BAZEL_BINDIR: the bazel bin directory; equivalent to the `$(BINDIR)` Make variable of the `js_run_binary` target
-    * BAZEL_COMPILATION_MODE (legacy; see `set_legacy_environment_variables`): One of `fastbuild`, `dbg`, or `opt` as set by [`--compilation_mode`](https://bazel.build/docs/user-manual#compilation-mode); equivalent to `$(COMPILATION_MODE)` Make variable of the `js_run_binary` target
     * BAZEL_TARGET_CPU (legacy; see `set_legacy_environment_variables`): the target cpu architecture; equivalent to `$(TARGET_CPU)` Make variable of the `js_run_binary` target
+    * BAZEL_COMPILATION_MODE (legacy; see `set_legacy_environment_variables`): One of `fastbuild`, `dbg`, or `opt` as set by [`--compilation_mode`](https://bazel.build/docs/user-manual#compilation-mode); equivalent to `$(COMPILATION_MODE)` Make variable of the `js_run_binary` target
 
     The following environment variables are made available to the Node.js runtime based on the rule context:
 
-    * BAZEL_BUILD_FILE_PATH: the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
     * BAZEL_PACKAGE: the package of the bazel target being run; equivalent to `ctx.label.package` of the `js_run_binary` target's rule context
     * BAZEL_TARGET_NAME: the full label of the bazel target being run; a stringified version of `ctx.label` of the `js_run_binary` target's rule context
-    * BAZEL_TARGET: the name of the bazel target being run; equivalent to `ctx.label.name` of the  `js_run_binary` target's rule context
-    * BAZEL_WORKSPACE: the bazel repository name; equivalent to `ctx.workspace_name` of the `js_run_binary` target's rule context
+    * BAZEL_BUILD_FILE_PATH (legacy; see `set_legacy_environment_variables`): the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
+    * BAZEL_TARGET (legacy; see `set_legacy_environment_variables`): the name of the bazel target being run; equivalent to `ctx.label.name` of the  `js_run_binary` target's rule context
+    * BAZEL_WORKSPACE (legacy; see `set_legacy_environment_variables`): the bazel repository name; equivalent to `ctx.workspace_name` of the `js_run_binary` target's rule context
 
     Args:
         name: Target name
@@ -272,8 +254,9 @@ def js_run_binary(
 
             Refer to https://bazel.build/rules/lib/builtins/actions#run for more details.
 
-        set_legacy_environment_variables: Whether to set the legacy `BAZEL_COMPILATION_MODE`
-            and `BAZEL_TARGET_CPU` environment variables.
+        set_legacy_environment_variables: Whether to set the legacy `BAZEL_BUILD_FILE_PATH`,
+            `BAZEL_COMPILATION_MODE`, `BAZEL_TARGET_CPU`, `BAZEL_TARGET` and `BAZEL_WORKSPACE`
+            environment variables.
 
             These variables are deprecated and setting them will default to False in a future
             release. Set this to False to opt out now.
@@ -322,27 +305,19 @@ def js_run_binary(
         extra_srcs.append(":{}".format(copy_to_bin_name))
 
     # Automatically add common and useful make variables to the environment for js_run_binary build targets
-    label = native.package_relative_label(name)
     fixed_env = {
-        "BAZEL_BUILD_FILE_PATH": _build_file_path(),
         "BAZEL_PACKAGE": native.package_name(),
         "BAZEL_TARGET_NAME": name,
-        "BAZEL_TARGET": "{}//{}:{}".format(
-            "@" + label.repo_name if label.repo_name else "",
-            label.package,
-            label.name,
-        ),
-        # This variable used to be derived from ctx.workspace_name and was the
-        # name from the WORKSPACE file, but with bzlmod it is always just
-        # "_main".
-        "BAZEL_WORKSPACE": "_main",
     }
 
     # These environment variables are deprecated and will default to not being set in a future
     # release; see the `set_legacy_environment_variables` docstring.
     if set_legacy_environment_variables:
+        fixed_env["BAZEL_BUILD_FILE_PATH"] = "$(BUILD_FILE_PATH)"
         fixed_env["BAZEL_COMPILATION_MODE"] = "$(COMPILATION_MODE)"
         fixed_env["BAZEL_TARGET_CPU"] = "$(TARGET_CPU)"
+        fixed_env["BAZEL_TARGET"] = "$(TARGET)"
+        fixed_env["BAZEL_WORKSPACE"] = "$(WORKSPACE)"
 
     # Configure working directory to `chdir` is set
     if chdir != None:

From 042330ed933fcc00ead72c3eeee86b4c0ed84f11 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 16:09:18 -0700
Subject: [PATCH 13/21] Simplify test

---
 e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel b/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
index 8b0e84baf4..69347a9a6c 100644
--- a/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
+++ b/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
@@ -12,7 +12,8 @@ js_binary(
 js_run_binary(
     name = "js_run_binary_path_mapping_check",
     outs = ["out.txt"],
-    args = [package_name() + "/out.txt"],
+    chdir = package_name(),
+    args = ["out.txt"],
     mnemonic = "JsRunBinaryPathMappingCheck",
     set_legacy_environment_variables = False,
     tool = ":check",

From 7f3ac976905ca9c1150a3a431c80ce2ce2b96411 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 16:11:37 -0700
Subject: [PATCH 14/21] Fix up ordering

---
 js/private/js_run_binary.bzl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index 4fe5022346..e7ea1c6ee9 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -54,14 +54,14 @@ def js_run_binary(
     The following environment variables are made available to the Node.js runtime based on available Bazel [Make variables](https://bazel.build/reference/be/make-variables#predefined_variables):
 
     * BAZEL_BINDIR: the bazel bin directory; equivalent to the `$(BINDIR)` Make variable of the `js_run_binary` target
-    * BAZEL_TARGET_CPU (legacy; see `set_legacy_environment_variables`): the target cpu architecture; equivalent to `$(TARGET_CPU)` Make variable of the `js_run_binary` target
     * BAZEL_COMPILATION_MODE (legacy; see `set_legacy_environment_variables`): One of `fastbuild`, `dbg`, or `opt` as set by [`--compilation_mode`](https://bazel.build/docs/user-manual#compilation-mode); equivalent to `$(COMPILATION_MODE)` Make variable of the `js_run_binary` target
+    * BAZEL_TARGET_CPU (legacy; see `set_legacy_environment_variables`): the target cpu architecture; equivalent to `$(TARGET_CPU)` Make variable of the `js_run_binary` target
 
     The following environment variables are made available to the Node.js runtime based on the rule context:
 
+    * BAZEL_BUILD_FILE_PATH (legacy; see `set_legacy_environment_variables`): the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
     * BAZEL_PACKAGE: the package of the bazel target being run; equivalent to `ctx.label.package` of the `js_run_binary` target's rule context
     * BAZEL_TARGET_NAME: the full label of the bazel target being run; a stringified version of `ctx.label` of the `js_run_binary` target's rule context
-    * BAZEL_BUILD_FILE_PATH (legacy; see `set_legacy_environment_variables`): the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
     * BAZEL_TARGET (legacy; see `set_legacy_environment_variables`): the name of the bazel target being run; equivalent to `ctx.label.name` of the  `js_run_binary` target's rule context
     * BAZEL_WORKSPACE (legacy; see `set_legacy_environment_variables`): the bazel repository name; equivalent to `ctx.workspace_name` of the `js_run_binary` target's rule context
 

From d8ce43112a41fb563304b3322da7a31cea4f60d4 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 16:14:24 -0700
Subject: [PATCH 15/21] Move BAZEL_PACKAGE and BAZEL_TARGET_NAME behind
 set_legacy_environment_variables

All seven js_run_binary-provided BAZEL_* env vars are now gated behind
the same flag, for consistency.
---
 js/private/js_run_binary.bzl | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index e7ea1c6ee9..7cbff45800 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -60,8 +60,8 @@ def js_run_binary(
     The following environment variables are made available to the Node.js runtime based on the rule context:
 
     * BAZEL_BUILD_FILE_PATH (legacy; see `set_legacy_environment_variables`): the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
-    * BAZEL_PACKAGE: the package of the bazel target being run; equivalent to `ctx.label.package` of the `js_run_binary` target's rule context
-    * BAZEL_TARGET_NAME: the full label of the bazel target being run; a stringified version of `ctx.label` of the `js_run_binary` target's rule context
+    * BAZEL_PACKAGE (legacy; see `set_legacy_environment_variables`): the package of the bazel target being run; equivalent to `ctx.label.package` of the `js_run_binary` target's rule context
+    * BAZEL_TARGET_NAME (legacy; see `set_legacy_environment_variables`): the full label of the bazel target being run; a stringified version of `ctx.label` of the `js_run_binary` target's rule context
     * BAZEL_TARGET (legacy; see `set_legacy_environment_variables`): the name of the bazel target being run; equivalent to `ctx.label.name` of the  `js_run_binary` target's rule context
     * BAZEL_WORKSPACE (legacy; see `set_legacy_environment_variables`): the bazel repository name; equivalent to `ctx.workspace_name` of the `js_run_binary` target's rule context
 
@@ -255,8 +255,8 @@ def js_run_binary(
             Refer to https://bazel.build/rules/lib/builtins/actions#run for more details.
 
         set_legacy_environment_variables: Whether to set the legacy `BAZEL_BUILD_FILE_PATH`,
-            `BAZEL_COMPILATION_MODE`, `BAZEL_TARGET_CPU`, `BAZEL_TARGET` and `BAZEL_WORKSPACE`
-            environment variables.
+            `BAZEL_COMPILATION_MODE`, `BAZEL_TARGET_CPU`, `BAZEL_TARGET`, `BAZEL_WORKSPACE`,
+            `BAZEL_PACKAGE` and `BAZEL_TARGET_NAME` environment variables.
 
             These variables are deprecated and setting them will default to False in a future
             release. Set this to False to opt out now.
@@ -305,10 +305,7 @@ def js_run_binary(
         extra_srcs.append(":{}".format(copy_to_bin_name))
 
     # Automatically add common and useful make variables to the environment for js_run_binary build targets
-    fixed_env = {
-        "BAZEL_PACKAGE": native.package_name(),
-        "BAZEL_TARGET_NAME": name,
-    }
+    fixed_env = {}
 
     # These environment variables are deprecated and will default to not being set in a future
     # release; see the `set_legacy_environment_variables` docstring.
@@ -318,6 +315,8 @@ def js_run_binary(
         fixed_env["BAZEL_TARGET_CPU"] = "$(TARGET_CPU)"
         fixed_env["BAZEL_TARGET"] = "$(TARGET)"
         fixed_env["BAZEL_WORKSPACE"] = "$(WORKSPACE)"
+        fixed_env["BAZEL_PACKAGE"] = native.package_name()
+        fixed_env["BAZEL_TARGET_NAME"] = name
 
     # Configure working directory to `chdir` is set
     if chdir != None:

From 6ab19569520a1a2c7d4e5feb86d98f3fbea60bfa Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 16:16:14 -0700
Subject: [PATCH 16/21] Remove outdated comment

---
 js/private/js_run_binary.bzl | 1 -
 1 file changed, 1 deletion(-)

diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index 7cbff45800..bd3543b2cd 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -304,7 +304,6 @@ def js_run_binary(
         )
         extra_srcs.append(":{}".format(copy_to_bin_name))
 
-    # Automatically add common and useful make variables to the environment for js_run_binary build targets
     fixed_env = {}
 
     # These environment variables are deprecated and will default to not being set in a future

From 88d464331860b4f8ad7c366a9ce2fd97618d2d3a Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 16:25:54 -0700
Subject: [PATCH 17/21] buildifier

---
 e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel b/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
index 69347a9a6c..183c116e40 100644
--- a/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
+++ b/e2e/path_mapping/js_run_binary_path_mapping_check/BUILD.bazel
@@ -12,8 +12,8 @@ js_binary(
 js_run_binary(
     name = "js_run_binary_path_mapping_check",
     outs = ["out.txt"],
-    chdir = package_name(),
     args = ["out.txt"],
+    chdir = package_name(),
     mnemonic = "JsRunBinaryPathMappingCheck",
     set_legacy_environment_variables = False,
     tool = ":check",

From 438cf1503844f3b4ad8127a7cb2c4c5c3cff0040 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Mon, 3 Aug 2026 20:16:48 -0700
Subject: [PATCH 18/21] Simplify comment

---
 js/private/js_run_binary.bzl | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index bd3543b2cd..4fcf8ac9dd 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -57,13 +57,13 @@ def js_run_binary(
     * BAZEL_COMPILATION_MODE (legacy; see `set_legacy_environment_variables`): One of `fastbuild`, `dbg`, or `opt` as set by [`--compilation_mode`](https://bazel.build/docs/user-manual#compilation-mode); equivalent to `$(COMPILATION_MODE)` Make variable of the `js_run_binary` target
     * BAZEL_TARGET_CPU (legacy; see `set_legacy_environment_variables`): the target cpu architecture; equivalent to `$(TARGET_CPU)` Make variable of the `js_run_binary` target
 
-    The following environment variables are made available to the Node.js runtime based on the rule context:
+    The following environment variables are made available to the Node.js runtime based on the rule context (all are legacy; see `set_legacy_environment_variables`):
 
-    * BAZEL_BUILD_FILE_PATH (legacy; see `set_legacy_environment_variables`): the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
-    * BAZEL_PACKAGE (legacy; see `set_legacy_environment_variables`): the package of the bazel target being run; equivalent to `ctx.label.package` of the `js_run_binary` target's rule context
-    * BAZEL_TARGET_NAME (legacy; see `set_legacy_environment_variables`): the full label of the bazel target being run; a stringified version of `ctx.label` of the `js_run_binary` target's rule context
-    * BAZEL_TARGET (legacy; see `set_legacy_environment_variables`): the name of the bazel target being run; equivalent to `ctx.label.name` of the  `js_run_binary` target's rule context
-    * BAZEL_WORKSPACE (legacy; see `set_legacy_environment_variables`): the bazel repository name; equivalent to `ctx.workspace_name` of the `js_run_binary` target's rule context
+    * BAZEL_BUILD_FILE_PATH: the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
+    * BAZEL_PACKAGE: the package of the bazel target being run; equivalent to `ctx.label.package` of the `js_run_binary` target's rule context
+    * BAZEL_TARGET_NAME: the full label of the bazel target being run; a stringified version of `ctx.label` of the `js_run_binary` target's rule context
+    * BAZEL_TARGET: the name of the bazel target being run; equivalent to `ctx.label.name` of the  `js_run_binary` target's rule context
+    * BAZEL_WORKSPACE: the bazel repository name; equivalent to `ctx.workspace_name` of the `js_run_binary` target's rule context
 
     Args:
         name: Target name

From 9c0bd7332d9235f76c4bdabde453c26ef2dc7688 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Tue, 4 Aug 2026 11:09:09 -0700
Subject: [PATCH 19/21] Explicitly set BAZEL_BINDIR if
 set_legacy_environment_variables

---
 js/private/js_run_binary.bzl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index 4fcf8ac9dd..82a58de66b 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -309,6 +309,7 @@ def js_run_binary(
     # These environment variables are deprecated and will default to not being set in a future
     # release; see the `set_legacy_environment_variables` docstring.
     if set_legacy_environment_variables:
+        fixed_env["BAZEL_BINDIR"] = "$(BINDIR)"
         fixed_env["BAZEL_BUILD_FILE_PATH"] = "$(BUILD_FILE_PATH)"
         fixed_env["BAZEL_COMPILATION_MODE"] = "$(COMPILATION_MODE)"
         fixed_env["BAZEL_TARGET_CPU"] = "$(TARGET_CPU)"

From 4b3f4188b993d5374479451648481ab5993faa7c Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Tue, 4 Aug 2026 14:22:36 -0700
Subject: [PATCH 20/21] Tweak comment

---
 js/private/js_run_binary.bzl | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index 82a58de66b..7d31931cbe 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -51,14 +51,11 @@ def js_run_binary(
 
     This rule does not require Bash `native.genrule`.
 
-    The following environment variables are made available to the Node.js runtime based on available Bazel [Make variables](https://bazel.build/reference/be/make-variables#predefined_variables):
+    The following environment variables are made available to the Node.js runtime if set_legacy_environment_variables is enabled. They are deprecated and will be removed in a future release:
 
     * BAZEL_BINDIR: the bazel bin directory; equivalent to the `$(BINDIR)` Make variable of the `js_run_binary` target
-    * BAZEL_COMPILATION_MODE (legacy; see `set_legacy_environment_variables`): One of `fastbuild`, `dbg`, or `opt` as set by [`--compilation_mode`](https://bazel.build/docs/user-manual#compilation-mode); equivalent to `$(COMPILATION_MODE)` Make variable of the `js_run_binary` target
-    * BAZEL_TARGET_CPU (legacy; see `set_legacy_environment_variables`): the target cpu architecture; equivalent to `$(TARGET_CPU)` Make variable of the `js_run_binary` target
-
-    The following environment variables are made available to the Node.js runtime based on the rule context (all are legacy; see `set_legacy_environment_variables`):
-
+    * BAZEL_COMPILATION_MODE: One of `fastbuild`, `dbg`, or `opt` as set by [`--compilation_mode`](https://bazel.build/docs/user-manual#compilation-mode); equivalent to `$(COMPILATION_MODE)` Make variable of the `js_run_binary` target
+    * BAZEL_TARGET_CPU: the target cpu architecture; equivalent to `$(TARGET_CPU)` Make variable of the `js_run_binary` target
     * BAZEL_BUILD_FILE_PATH: the path to the BUILD file of the bazel target being run; equivalent to `ctx.build_file_path` of the `js_run_binary` target's rule context
     * BAZEL_PACKAGE: the package of the bazel target being run; equivalent to `ctx.label.package` of the `js_run_binary` target's rule context
     * BAZEL_TARGET_NAME: the full label of the bazel target being run; a stringified version of `ctx.label` of the `js_run_binary` target's rule context

From 4722d213aba15b1925dc0325ba510f9cd1f0e272 Mon Sep 17 00:00:00 2001
From: Adam Cozzette <adamc@aspect.build>
Date: Tue, 4 Aug 2026 14:23:58 -0700
Subject: [PATCH 21/21] Fix comment

---
 js/private/js_run_binary.bzl | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/js/private/js_run_binary.bzl b/js/private/js_run_binary.bzl
index 7d31931cbe..40ae93b4f0 100644
--- a/js/private/js_run_binary.bzl
+++ b/js/private/js_run_binary.bzl
@@ -251,9 +251,10 @@ def js_run_binary(
 
             Refer to https://bazel.build/rules/lib/builtins/actions#run for more details.
 
-        set_legacy_environment_variables: Whether to set the legacy `BAZEL_BUILD_FILE_PATH`,
-            `BAZEL_COMPILATION_MODE`, `BAZEL_TARGET_CPU`, `BAZEL_TARGET`, `BAZEL_WORKSPACE`,
-            `BAZEL_PACKAGE` and `BAZEL_TARGET_NAME` environment variables.
+        set_legacy_environment_variables: Whether to set the legacy `BAZEL_BINDIR`,
+            `BAZEL_BUILD_FILE_PATH`, `BAZEL_COMPILATION_MODE`, `BAZEL_TARGET_CPU`,
+            `BAZEL_TARGET`, `BAZEL_WORKSPACE`, `BAZEL_PACKAGE` and `BAZEL_TARGET_NAME`
+            environment variables.
 
             These variables are deprecated and setting them will default to False in a future
             release. Set this to False to opt out now.