diff --git a/Cargo.lock b/Cargo.lock
index 41cc68a0..6f178b54 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -71,7 +71,7 @@ version = "1.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "40c48f72fd53cd289104fc64099abca73db4166ad86ea0b4341abe65af83dadc"
 dependencies = [
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -82,7 +82,7 @@ checksum = "291e6a250ff86cd4a820112fb8898808a366d8f9f58ce16d1f538353ad55747d"
 dependencies = [
  "anstyle",
  "once_cell_polyfill",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -842,7 +842,7 @@ dependencies = [
  "libc",
  "option-ext",
  "redox_users",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -881,7 +881,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
 dependencies = [
  "libc",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -1502,6 +1502,15 @@ dependencies = [
  "zstd",
 ]
 
+[[package]]
+name = "fdeflate"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e6853b52649d4ac5c0bd02320cddc5ba956bdb407c4b75a2c6b75bf51500f8c"
+dependencies = [
+ "simd-adler32",
+]
+
 [[package]]
 name = "filetime"
 version = "0.2.27"
@@ -1679,6 +1688,16 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "gethostname"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1bd49230192a3797a9a4d6abe9b3eed6f7fa4c8a8a4947977c6f80025f92cbd8"
+dependencies = [
+ "rustix",
+ "windows-link",
+]
+
 [[package]]
 name = "getrandom"
 version = "0.2.17"
@@ -2148,7 +2167,7 @@ checksum = "3640c1c38b8e4e43584d8df18be5fc6b0aa314ce6ebf51b53313d4306cca8e46"
 dependencies = [
  "hermit-abi",
  "libc",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -2582,7 +2601,7 @@ version = "0.50.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7957b9740744892f114936ab4a57b3f487491bbeafaf8083688b16841a4240e5"
 dependencies = [
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -2714,6 +2733,19 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b4596b6d070b27117e987119b4dac604f3c58cfb0b191112e24771b2faeac1a6"
 
+[[package]]
+name = "png"
+version = "0.17.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "82151a2fc869e011c153adc57cf2789ccb8d9906ce52c0b39a6b5697749d7526"
+dependencies = [
+ "bitflags 1.3.2",
+ "crc32fast",
+ "fdeflate",
+ "flate2",
+ "miniz_oxide",
+]
+
 [[package]]
 name = "portable-atomic"
 version = "1.13.1"
@@ -3073,7 +3105,7 @@ dependencies = [
  "once_cell",
  "socket2",
  "tracing",
- "windows-sys 0.60.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -3379,8 +3411,8 @@ dependencies = [
 
 [[package]]
 name = "running-process"
-version = "4.6.4"
-source = "git+https://github.com/zackees/running-process.git?rev=59556ebbb779a66a95811c75bb1533cf3db1c525#59556ebbb779a66a95811c75bb1533cf3db1c525"
+version = "4.8.1"
+source = "git+https://github.com/zackees/running-process.git?rev=359b4e3d92660e54eb9b16b6e83de8ce26932ff8#359b4e3d92660e54eb9b16b6e83de8ce26932ff8"
 dependencies = [
  "anyhow",
  "blake3",
@@ -3389,6 +3421,7 @@ dependencies = [
  "getrandom 0.4.2",
  "interprocess",
  "libc",
+ "png",
  "prost",
  "prost-build",
  "prost-types",
@@ -3402,6 +3435,7 @@ dependencies = [
  "toml 0.8.23",
  "winapi",
  "windows-sys 0.59.0",
+ "x11rb",
 ]
 
 [[package]]
@@ -3443,7 +3477,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -3725,7 +3759,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3a766e1110788c36f4fa1c2b71b387a7815aa65f88ce0229841826633d93723e"
 dependencies = [
  "libc",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -3879,7 +3913,7 @@ dependencies = [
  "getrandom 0.4.2",
  "once_cell",
  "rustix",
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -4628,7 +4662,7 @@ version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22"
 dependencies = [
- "windows-sys 0.60.2",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -4644,7 +4678,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e48a53791691ab099e5e2ad123536d0fff50652600abaf43bbf952894110d0be"
 dependencies = [
  "windows-core 0.52.0",
- "windows-targets 0.52.6",
+ "windows-targets",
 ]
 
 [[package]]
@@ -4674,7 +4708,7 @@ version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "33ab640c8d7e35bf8ba19b884ba838ceb4fba93a4e8c65a9059d08afcfc683d9"
 dependencies = [
- "windows-targets 0.52.6",
+ "windows-targets",
 ]
 
 [[package]]
@@ -4763,7 +4797,7 @@ version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
 dependencies = [
- "windows-targets 0.52.6",
+ "windows-targets",
 ]
 
 [[package]]
@@ -4772,16 +4806,7 @@ version = "0.59.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
 dependencies = [
- "windows-targets 0.52.6",
-]
-
-[[package]]
-name = "windows-sys"
-version = "0.60.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f2f500e4d28234f72040990ec9d39e3a6b950f9f22d3dba18416c35882612bcb"
-dependencies = [
- "windows-targets 0.53.5",
+ "windows-targets",
 ]
 
 [[package]]
@@ -4799,31 +4824,14 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
 dependencies = [
- "windows_aarch64_gnullvm 0.52.6",
- "windows_aarch64_msvc 0.52.6",
- "windows_i686_gnu 0.52.6",
- "windows_i686_gnullvm 0.52.6",
- "windows_i686_msvc 0.52.6",
- "windows_x86_64_gnu 0.52.6",
- "windows_x86_64_gnullvm 0.52.6",
- "windows_x86_64_msvc 0.52.6",
-]
-
-[[package]]
-name = "windows-targets"
-version = "0.53.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4945f9f551b88e0d65f3db0bc25c33b8acea4d9e41163edf90dcd0b19f9069f3"
-dependencies = [
- "windows-link",
- "windows_aarch64_gnullvm 0.53.1",
- "windows_aarch64_msvc 0.53.1",
- "windows_i686_gnu 0.53.1",
- "windows_i686_gnullvm 0.53.1",
- "windows_i686_msvc 0.53.1",
- "windows_x86_64_gnu 0.53.1",
- "windows_x86_64_gnullvm 0.53.1",
- "windows_x86_64_msvc 0.53.1",
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
 ]
 
 [[package]]
@@ -4841,96 +4849,48 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
 
-[[package]]
-name = "windows_aarch64_gnullvm"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a9d8416fa8b42f5c947f8482c43e7d89e73a173cead56d044f6a56104a6d1b53"
-
 [[package]]
 name = "windows_aarch64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
 
-[[package]]
-name = "windows_aarch64_msvc"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b9d782e804c2f632e395708e99a94275910eb9100b2114651e04744e9b125006"
-
 [[package]]
 name = "windows_i686_gnu"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
 
-[[package]]
-name = "windows_i686_gnu"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "960e6da069d81e09becb0ca57a65220ddff016ff2d6af6a223cf372a506593a3"
-
 [[package]]
 name = "windows_i686_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
 
-[[package]]
-name = "windows_i686_gnullvm"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fa7359d10048f68ab8b09fa71c3daccfb0e9b559aed648a8f95469c27057180c"
-
 [[package]]
 name = "windows_i686_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
 
-[[package]]
-name = "windows_i686_msvc"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e7ac75179f18232fe9c285163565a57ef8d3c89254a30685b57d83a38d326c2"
-
 [[package]]
 name = "windows_x86_64_gnu"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
 
-[[package]]
-name = "windows_x86_64_gnu"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c3842cdd74a865a8066ab39c8a7a473c0778a3f29370b5fd6b4b9aa7df4a499"
-
 [[package]]
 name = "windows_x86_64_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
 
-[[package]]
-name = "windows_x86_64_gnullvm"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0ffa179e2d07eee8ad8f57493436566c7cc30ac536a3379fdf008f47f6bb7ae1"
-
 [[package]]
 name = "windows_x86_64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
 
-[[package]]
-name = "windows_x86_64_msvc"
-version = "0.53.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d6bbff5f0aada427a1e5a6da5f1f98158182f26556f345ac9e04d36d0ebed650"
-
 [[package]]
 name = "winnow"
 version = "0.7.15"
@@ -5052,6 +5012,23 @@ dependencies = [
  "tap",
 ]
 
+[[package]]
+name = "x11rb"
+version = "0.13.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9993aa5be5a26815fe2c3eacfc1fde061fc1a1f094bf1ad2a18bf9c495dd7414"
+dependencies = [
+ "gethostname",
+ "rustix",
+ "x11rb-protocol",
+]
+
+[[package]]
+name = "x11rb-protocol"
+version = "0.13.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea6fc2961e4ef194dcbfe56bb845534d0dc8098940c7e5c012a258bfec6701bd"
+
 [[package]]
 name = "xattr"
 version = "1.6.1"
@@ -5096,8 +5073,8 @@ dependencies = [
 
 [[package]]
 name = "zccache"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "arc-swap",
  "bincode",
@@ -5150,12 +5127,13 @@ dependencies = [
 
 [[package]]
 name = "zccache-artifact"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "bincode",
  "blake3",
  "dashmap",
+ "fs2",
  "prost",
  "rayon",
  "redb",
@@ -5172,8 +5150,8 @@ dependencies = [
 
 [[package]]
 name = "zccache-audit"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "serde",
  "serde_json",
@@ -5182,16 +5160,16 @@ dependencies = [
 
 [[package]]
 name = "zccache-compile-trace"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "zccache-audit",
 ]
 
 [[package]]
 name = "zccache-compiler"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "clang",
  "serde_json",
@@ -5202,8 +5180,8 @@ dependencies = [
 
 [[package]]
 name = "zccache-core"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "crash-handler",
  "libc",
@@ -5216,8 +5194,8 @@ dependencies = [
 
 [[package]]
 name = "zccache-daemon-core"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "arc-swap",
  "bincode",
@@ -5266,8 +5244,8 @@ dependencies = [
 
 [[package]]
 name = "zccache-depgraph"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "bincode",
  "blake3",
@@ -5286,8 +5264,8 @@ dependencies = [
 
 [[package]]
 name = "zccache-fingerprint"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "fs2",
  "globset",
@@ -5304,8 +5282,8 @@ dependencies = [
 
 [[package]]
 name = "zccache-fscache"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "bincode",
  "dashmap",
@@ -5319,8 +5297,8 @@ dependencies = [
 
 [[package]]
 name = "zccache-hash"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "blake3",
  "memmap2",
@@ -5329,8 +5307,8 @@ dependencies = [
 
 [[package]]
 name = "zccache-ipc"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "bytes",
  "dashmap",
@@ -5349,8 +5327,8 @@ dependencies = [
 
 [[package]]
 name = "zccache-protocol"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "bincode",
  "bytes",
@@ -5366,8 +5344,8 @@ dependencies = [
 
 [[package]]
 name = "zccache-watcher"
-version = "1.12.17"
-source = "git+https://github.com/zackees/zccache?rev=5ee292ff61e0f5909e1893916efe3bd963db8032#5ee292ff61e0f5909e1893916efe3bd963db8032"
+version = "1.13.1"
+source = "git+https://github.com/zackees/zccache?rev=8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e#8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e"
 dependencies = [
  "globset",
  "jwalk",
diff --git a/Cargo.toml b/Cargo.toml
index 6102fd93..c0fdbf3d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -161,7 +161,7 @@ owo-colors = "4"
 # duplicate symbol: rp_native_process_start_public`, …). Keep this rev in
 # lockstep with the `rev` in zccache's workspace Cargo.toml when repinning
 # zccache.
-running-process = { version = "4.6.0", git = "https://github.com/zackees/running-process.git", rev = "59556ebbb779a66a95811c75bb1533cf3db1c525", default-features = false, features = ["client-async"] }
+running-process = { version = "4.8.1", git = "https://github.com/zackees/running-process.git", rev = "359b4e3d92660e54eb9b16b6e83de8ce26932ff8", default-features = false, features = ["client-async"] }
 
 [profile.dev]
 debug = "line-tables-only"
diff --git a/crates/fbuild-build-arm/Cargo.toml b/crates/fbuild-build-arm/Cargo.toml
index e8818f9f..2ec73cf5 100644
--- a/crates/fbuild-build-arm/Cargo.toml
+++ b/crates/fbuild-build-arm/Cargo.toml
@@ -34,7 +34,7 @@ tar = { workspace = true }
 zip = { workspace = true }
 tree-sitter = { workspace = true }
 tree-sitter-cpp = { workspace = true }
-zccache = { git = "https://github.com/zackees/zccache", rev = "5ee292ff61e0f5909e1893916efe3bd963db8032" }
+zccache = { git = "https://github.com/zackees/zccache", rev = "8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e" }
 
 [dev-dependencies]
 filetime = { workspace = true }
diff --git a/crates/fbuild-build-engine/Cargo.toml b/crates/fbuild-build-engine/Cargo.toml
index c3d79a60..d38354df 100644
--- a/crates/fbuild-build-engine/Cargo.toml
+++ b/crates/fbuild-build-engine/Cargo.toml
@@ -34,7 +34,7 @@ tar = { workspace = true }
 zip = { workspace = true }
 tree-sitter = { workspace = true }
 tree-sitter-cpp = { workspace = true }
-zccache = { git = "https://github.com/zackees/zccache", rev = "5ee292ff61e0f5909e1893916efe3bd963db8032" }
+zccache = { git = "https://github.com/zackees/zccache", rev = "8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e" }
 
 [dev-dependencies]
 filetime = { workspace = true }
diff --git a/crates/fbuild-build-esp/Cargo.toml b/crates/fbuild-build-esp/Cargo.toml
index c4353e7c..07a76cdd 100644
--- a/crates/fbuild-build-esp/Cargo.toml
+++ b/crates/fbuild-build-esp/Cargo.toml
@@ -34,7 +34,7 @@ tar = { workspace = true }
 zip = { workspace = true }
 tree-sitter = { workspace = true }
 tree-sitter-cpp = { workspace = true }
-zccache = { git = "https://github.com/zackees/zccache", rev = "5ee292ff61e0f5909e1893916efe3bd963db8032" }
+zccache = { git = "https://github.com/zackees/zccache", rev = "8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e" }
 
 [dev-dependencies]
 filetime = { workspace = true }
diff --git a/crates/fbuild-build-mcu/Cargo.toml b/crates/fbuild-build-mcu/Cargo.toml
index a5309ffa..181fa8e9 100644
--- a/crates/fbuild-build-mcu/Cargo.toml
+++ b/crates/fbuild-build-mcu/Cargo.toml
@@ -34,7 +34,7 @@ tar = { workspace = true }
 zip = { workspace = true }
 tree-sitter = { workspace = true }
 tree-sitter-cpp = { workspace = true }
-zccache = { git = "https://github.com/zackees/zccache", rev = "5ee292ff61e0f5909e1893916efe3bd963db8032" }
+zccache = { git = "https://github.com/zackees/zccache", rev = "8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e" }
 
 [dev-dependencies]
 filetime = { workspace = true }
diff --git a/crates/fbuild-build/Cargo.toml b/crates/fbuild-build/Cargo.toml
index 876b7164..9aee3bb4 100644
--- a/crates/fbuild-build/Cargo.toml
+++ b/crates/fbuild-build/Cargo.toml
@@ -56,7 +56,7 @@ tree-sitter-cpp = { workspace = true }
 #
 # `running-process` in the workspace root must be pinned to the SAME git rev
 # zccache uses, or its unmangled `rp_*_public` C symbols get linked twice.
-zccache = { git = "https://github.com/zackees/zccache", rev = "5ee292ff61e0f5909e1893916efe3bd963db8032" }
+zccache = { git = "https://github.com/zackees/zccache", rev = "8cf6dd0ef5d6f2ff2980039290b9e498fb5a6b0e" }
 
 [dev-dependencies]
 filetime = { workspace = true }
diff --git a/crates/fbuild-core/tests/README.md b/crates/fbuild-core/tests/README.md
new file mode 100644
index 00000000..d8cf7f78
--- /dev/null
+++ b/crates/fbuild-core/tests/README.md
@@ -0,0 +1,10 @@
+# fbuild-core integration tests
+
+- **`dep_identity.rs`** -- regression guard for FastLED/fbuild#1239. fbuild
+  embeds zccache and also depends directly on `running-process`, whose
+  unmangled `rp_*_public` native symbols mean that resolving two package
+  identities would link two copies of those symbols. The test parses the
+  workspace `Cargo.lock` and fails if more than one `running-process`
+  package identity/source/revision is resolved, and mechanically checks
+  that the workspace `Cargo.toml` pin matches the locked revision (i.e.
+  fbuild's direct pin equals the revision zccache resolved transitively).
diff --git a/crates/fbuild-core/tests/dep_identity.rs b/crates/fbuild-core/tests/dep_identity.rs
new file mode 100644
index 00000000..bdfa12a3
--- /dev/null
+++ b/crates/fbuild-core/tests/dep_identity.rs
@@ -0,0 +1,91 @@
+//! Regression guard for FastLED/fbuild#1239: the workspace must resolve
+//! exactly ONE `running-process` package identity.
+//!
+//! fbuild depends on `running-process` directly AND transitively through
+//! the embedded zccache. `running-process` exports unmangled
+//! `rp_*_public` native symbols, so two resolved identities (two
+//! versions, two sources, or two revisions) would link two copies of
+//! those symbols into fbuild. The dependency cascade discipline is:
+//! fbuild's direct git pin must be byte-identical to the pin inside the
+//! zccache release fbuild embeds — this test fails the build when the
+//! pins drift apart.
+
+use std::path::Path;
+
+fn workspace_root() -> &'static Path {
+    // crates/fbuild-core -> workspace root.
+    Path::new(env!("CARGO_MANIFEST_DIR"))
+        .parent()
+        .and_then(Path::parent)
+        .expect("workspace root above crates/fbuild-core")
+}
+
+/// Extract every `[[package]]` block for `name` from Cargo.lock, returning
+/// each block's `(version, source)` pair.
+fn locked_packages(lock: &str, name: &str) -> Vec<(String, String)> {
+    let mut found = Vec::new();
+    for block in lock.split("[[package]]") {
+        let mut pkg_name = None;
+        let mut version = None;
+        let mut source = None;
+        for line in block.lines().map(str::trim) {
+            if let Some(v) = line.strip_prefix("name = ") {
+                pkg_name = Some(v.trim_matches('"').to_string());
+            } else if let Some(v) = line.strip_prefix("version = ") {
+                version = Some(v.trim_matches('"').to_string());
+            } else if let Some(v) = line.strip_prefix("source = ") {
+                source = Some(v.trim_matches('"').to_string());
+            }
+        }
+        if pkg_name.as_deref() == Some(name) {
+            found.push((version.unwrap_or_default(), source.unwrap_or_default()));
+        }
+    }
+    found
+}
+
+/// The `rev = "..."` recorded for `dep` in the workspace Cargo.toml.
+fn workspace_pin_rev(cargo_toml: &str, dep: &str) -> String {
+    let line = cargo_toml
+        .lines()
+        .find(|l| l.trim_start().starts_with(&format!("{dep} = {{")))
+        .unwrap_or_else(|| panic!("no `{dep}` dependency line in workspace Cargo.toml"));
+    let rev_key = "rev = \"";
+    let start = line
+        .find(rev_key)
+        .unwrap_or_else(|| panic!("`{dep}` line has no rev pin: {line}"))
+        + rev_key.len();
+    line[start..]
+        .split('"')
+        .next()
+        .expect("terminated rev string")
+        .to_string()
+}
+
+#[test]
+fn exactly_one_running_process_identity_matching_the_workspace_pin() {
+    let root = workspace_root();
+    let lock = std::fs::read_to_string(root.join("Cargo.lock")).expect("read Cargo.lock");
+    let cargo_toml =
+        std::fs::read_to_string(root.join("Cargo.toml")).expect("read workspace Cargo.toml");
+
+    let packages = locked_packages(&lock, "running-process");
+    assert_eq!(
+        packages.len(),
+        1,
+        "Cargo.lock must resolve exactly one `running-process` identity — \
+         multiple identities link duplicate rp_*_public symbols \
+         (FastLED/fbuild#1239). Resolved: {packages:?}"
+    );
+
+    let (version, source) = &packages[0];
+    let pinned_rev = workspace_pin_rev(&cargo_toml, "running-process");
+    assert!(
+        source.contains(&pinned_rev),
+        "the locked running-process source must be the workspace-pinned rev.\n  \
+         locked:  {version} @ {source}\n  \
+         pinned:  {pinned_rev}\n  \
+         The direct pin and the zccache release's transitive pin have drifted — \
+         re-run the FastLED/fbuild#1239 cascade (running-process -> zccache -> fbuild)."
+    );
+}