Add --screenshot CLI mode for automated capture

Renders a single view ("bar" or "control-panel"), captures it via
bread-screenshots, then exits — driven by bread-ecosystem's bread-capture
orchestrator, or runnable standalone for one-off captures.

Waits on GTK's map signal (plus a short settle delay) before capturing
rather than guessing a fixed sleep upfront: the control-panel view in
particular needs the popover's autohide disabled (a programmatic popup()
has no input-event serial to grab the Wayland seat with) and a longer
settle window so the CPU/RAM/PWR/GPU/network stats — populated by a
2-second background poller, not the popover's own open — have had at
least one full cycle to fill in before the capture fires.

--width/--height match whatever canvas bread-capture's isolation sizes
the compositor to, so the "bar" view's geometry doesn't depend on
querying anything at capture time.

Needs RelmApp::with_args(vec![]) (GLib's own arg parser otherwise rejects
--screenshot/--output before clap ever sees them) and
allow_multiple_instances(true) for screenshot runs specifically, since
GApplication is single-instance by default and this machine typically
already has a real breadbar running.

Cargo.lock

@@ -8,6 +8,62 @@ version = "2.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "320119579fcad9c21884f5c4861d16174d0e06250625266f50fe6898340abefa"
 
+[[package]]
+name = "anstream"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "824a212faf96e9acacdbd09febd34438f8f711fb84e09a8916013cd7815ca28d"
+dependencies = [
+ "anstyle",
+ "anstyle-parse",
+ "anstyle-query",
+ "anstyle-wincon",
+ "colorchoice",
+ "is_terminal_polyfill",
+ "utf8parse",
+]
+
+[[package]]
+name = "anstyle"
+version = "1.0.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "940b3a0ca603d1eade50a4846a2afffd5ef57a9feac2c0e2ec2e14f9ead76000"
+
+[[package]]
+name = "anstyle-parse"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "52ce7f38b242319f7cabaa6813055467063ecdc9d355bbb4ce0c68908cd8130e"
+dependencies = [
+ "utf8parse",
+]
+
+[[package]]
+name = "anstyle-query"
+version = "1.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "40c48f72fd53cd289104fc64099abca73db4166ad86ea0b4341abe65af83dadc"
+dependencies = [
+ "windows-sys 0.61.2",
+]
+
+[[package]]
+name = "anstyle-wincon"
+version = "3.0.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "291e6a250ff86cd4a820112fb8898808a366d8f9f58ce16d1f538353ad55747d"
+dependencies = [
+ "anstyle",
+ "once_cell_polyfill",
+ "windows-sys 0.61.2",
+]
+
+[[package]]
+name = "anyhow"
+version = "1.0.104"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "330a5ed07fa54e4702c9d6c4174f74427fc0ef6e214bbd677ae50a5099946470"
+
 [[package]]
 name = "arrayref"
 version = "0.3.9"
@@ -40,7 +96,7 @@ checksum = "3b43422f69d8ff38f95f1b2bb76517c91589a924d1559a0e935d7c8ce0274c11"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
 ]
 
 [[package]]
@@ -62,18 +118,18 @@ checksum = "c7c24de15d275a1ecfd47a380fb4d5ec9bfe0933f309ed5e705b775596a3574d"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
 ]
 
 [[package]]
 name = "async-trait"
-version = "0.1.89"
+version = "0.1.91"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9035ad2d096bed7955a320ee7e2230574d28fd3c3a0f186cbea1ff3c7eed5dbb"
+checksum = "ae36dc4177970ef04fde5178d3e2429882def40e57a451f919c098f72baa6cec"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 3.0.3",
 ]
 
 [[package]]
@@ -94,12 +150,22 @@ version = "2.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b588b76d00fde79687d7646a9b5bdf3cc0f655e0bbd080335a95d7e96f3587da"
 
+[[package]]
+name = "bread-screenshots"
+version = "0.3.1"
+source = "git+https://git.breadway.dev/Breadway/bread-ecosystem?branch=dev#686af0d3dc93bf8039d62fbbd1e04a8b2db90154"
+dependencies = [
+ "anyhow",
+ "bread-utils",
+ "tracing",
+]
+
 [[package]]
 name = "bread-shared"
 version = "0.7.0"
 source = "git+https://git.breadway.dev/Breadway/bread?tag=v0.7.0#22e34e2cf2202305d7960759dfccb54dc79f948b"
 dependencies = [
- "dirs",
+ "dirs 5.0.1",
  "serde",
  "serde_json",
  "toml 0.8.23",
@@ -108,9 +174,9 @@ dependencies = [
 [[package]]
 name = "bread-shared"
 version = "0.7.0"
-source = "git+https://git.breadway.dev/Breadway/bread?branch=dev#8a794c03bfc7f2f294ff89d92494ad324afc30f5"
+source = "git+https://git.breadway.dev/Breadway/bread?branch=dev#34854f147135143ca4baf1d628e8c609e2c1cc8c"
 dependencies = [
- "dirs",
+ "dirs 6.0.0",
  "serde",
  "serde_json",
  "toml 0.8.23",
@@ -119,9 +185,9 @@ dependencies = [
 [[package]]
 name = "bread-theme"
 version = "0.3.1"
-source = "git+https://github.com/Breadway/bread-ecosystem?branch=dev#77bca8a1cf90d7fd38745270d2deb291b8b22bfe"
+source = "git+https://github.com/Breadway/bread-ecosystem?branch=dev#686af0d3dc93bf8039d62fbbd1e04a8b2db90154"
 dependencies = [
- "dirs",
+ "dirs 5.0.1",
  "gtk4",
  "serde",
  "serde_json",
@@ -130,10 +196,10 @@ dependencies = [
 [[package]]
 name = "bread-utils"
 version = "0.3.1"
-source = "git+https://git.breadway.dev/Breadway/bread-ecosystem?branch=dev#77bca8a1cf90d7fd38745270d2deb291b8b22bfe"
+source = "git+https://git.breadway.dev/Breadway/bread-ecosystem?branch=dev#686af0d3dc93bf8039d62fbbd1e04a8b2db90154"
 dependencies = [
  "bread-shared 0.7.0 (git+https://git.breadway.dev/Breadway/bread?tag=v0.7.0)",
- "dirs",
+ "dirs 5.0.1",
  "serde",
  "serde_json",
 ]
@@ -142,9 +208,12 @@ dependencies = [
 name = "breadbar"
 version = "0.3.0"
 dependencies = [
+ "anyhow",
+ "bread-screenshots",
  "bread-shared 0.7.0 (git+https://git.breadway.dev/Breadway/bread?branch=dev)",
  "bread-theme",
  "bread-utils",
+ "clap",
  "futures-lite",
  "gtk4",
  "gtk4-layer-shell",
@@ -165,9 +234,9 @@ checksum = "72f5acc6cb2ba439de613abc23857ec3d78374d8ed5ac84e9d11336e87da8649"
 
 [[package]]
 name = "bytemuck"
-version = "1.25.1"
+version = "1.25.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d6aedf8ae72766347502cf3cb4f41cf5e9cc37d28bee90f1fdaaae15f9cf9424"
+checksum = "95832e849adfb21180ccb6826a99da14e5d266ae5c2e668e1602cf234f153797"
 
 [[package]]
 name = "bytes"
@@ -215,14 +284,51 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
 [[package]]
-name = "concurrent-queue"
+name = "clap"
-version = "2.5.0"
+version = "4.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4ca0197aee26d1ae37445ee532fefce43251d24cc7c166799f4d46817f1d3973"
+checksum = "d91e0c145792ef73a6ad36d27c75ac09f1832222a3c209689d90f534685ee5b7"
 dependencies = [
- "crossbeam-utils",
+ "clap_builder",
+ "clap_derive",
 ]
 
+[[package]]
+name = "clap_builder"
+version = "4.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f09628afdcc538b57f3c6341e9c8e9970f18e4a481690a64974d7023bd33548b"
+dependencies = [
+ "anstream",
+ "anstyle",
+ "clap_lex",
+ "strsim",
+]
+
+[[package]]
+name = "clap_derive"
+version = "4.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d012d2b9d65aca7f18f4d9878a045bc17899bba951561ba5ec3c2ba1eed9a061"
+dependencies = [
+ "heck",
+ "proc-macro2",
+ "quote",
+ "syn 3.0.3",
+]
+
+[[package]]
+name = "clap_lex"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c8d4a3bb8b1e0c1050499d1815f5ab16d04f0959b233085fb31653fbfc9d98f9"
+
+[[package]]
+name = "colorchoice"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d07550c9036bf2ae0c684c4297d503f838287c83c53686d05370d0e139ae570"
+
 [[package]]
 name = "convert_case"
 version = "0.10.0"
@@ -241,12 +347,6 @@ dependencies = [
  "cfg-if",
 ]
 
-[[package]]
-name = "crossbeam-utils"
-version = "0.8.22"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "61803da095bee82a81bb1a452ecc25d3b2f1416d1897eb86430c6159ef717c17"
-
 [[package]]
 name = "data-url"
 version = "0.3.2"
@@ -272,7 +372,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "rustc_version",
- "syn",
+ "syn 2.0.119",
  "unicode-xid",
 ]
 
@@ -282,7 +382,16 @@ version = "5.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "44c45a9d03d6676652bcb5e724c7e988de1acad23a711b5217ab9cbecbec2225"
 dependencies = [
- "dirs-sys",
+ "dirs-sys 0.4.1",
+]
+
+[[package]]
+name = "dirs"
+version = "6.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3e8aa94d75141228480295a7d0e7feb620b1a5ad9f12bc40be62411e38cce4e"
+dependencies = [
+ "dirs-sys 0.5.0",
 ]
 
 [[package]]
@@ -293,15 +402,27 @@ checksum = "520f05a5cbd335fae5a99ff7a6ab8627577660ee5cfd6a94a6a929b52ff0321c"
 dependencies = [
  "libc",
  "option-ext",
- "redox_users",
+ "redox_users 0.4.6",
  "windows-sys 0.48.0",
 ]
 
 [[package]]
-name = "either"
+name = "dirs-sys"
-version = "1.16.0"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "91622ff5e7162018101f2fea40d6ebf4a78bbe5a49736a2020649edf9693679e"
+checksum = "e01a3366d27ee9890022452ee61b2b63a67e6f13f58900b651ff5665f0bb1fab"
+dependencies = [
+ "libc",
+ "option-ext",
+ "redox_users 0.5.2",
+ "windows-sys 0.61.2",
+]
+
+[[package]]
+name = "either"
+version = "1.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9e5e8f6c15a24b9a3ee5efec809ccd006d3b30e8b3bb63c39af737c7f87daa1d"
 
 [[package]]
 name = "endi"
@@ -327,7 +448,7 @@ checksum = "67c78a4d8fdf9953a5c9d458f9efe940fd97a0cab0941c075a813ac594733827"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
 ]
 
 [[package]]
@@ -357,11 +478,10 @@ dependencies = [
 
 [[package]]
 name = "event-listener"
-version = "5.4.1"
+version = "5.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e13b66accf52311f30a0db42147dadea9850cb48cd070028831ae5f5d4b856ab"
+checksum = "5a23add41df1562121a9393cb065eab5146a1242410f23a644851e90cfd669d2"
 dependencies = [
- "concurrent-queue",
  "parking",
  "pin-project-lite",
 ]
@@ -378,11 +498,11 @@ dependencies = [
 
 [[package]]
 name = "fastrand"
-version = "2.4.1"
+version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9f1f227452a390804cdb637b74a86990f2a7d7ba4b7d5693aac9b4dd6defd8d6"
+checksum = "da7c62ceae207dd37ea5b845da6a0696c799f85e97da1ab5b7910be3c1c80223"
 dependencies = [
- "getrandom 0.3.4",
+ "getrandom 0.4.3",
 ]
 
 [[package]]
@@ -510,7 +630,7 @@ checksum = "2d6d3cde68c518367be28956066ddfef33813991b77a55005a69dae04bf3b10b"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
 ]
 
 [[package]]
@@ -611,20 +731,6 @@ dependencies = [
  "wasi",
 ]
 
-[[package]]
-name = "getrandom"
-version = "0.3.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "899def5c37c4fd7b2664648c28120ecec138e4d395b459e5ca34f9cce2dd77fd"
-dependencies = [
- "cfg-if",
- "js-sys",
- "libc",
- "r-efi 5.3.0",
- "wasip2",
- "wasm-bindgen",
-]
-
 [[package]]
 name = "getrandom"
 version = "0.4.3"
@@ -632,8 +738,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "300e883d756b2e4ec94e02791f39b04b522276138852cfc41d9fb7e904106099"
 dependencies = [
  "cfg-if",
+ "js-sys",
  "libc",
- "r-efi 6.0.0",
+ "r-efi",
+ "wasm-bindgen",
 ]
 
 [[package]]
@@ -716,7 +824,7 @@ dependencies = [
  "heck",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
 ]
 
 [[package]]
@@ -850,7 +958,7 @@ dependencies = [
  "proc-macro-crate",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
 ]
 
 [[package]]
@@ -916,7 +1024,7 @@ checksum = "31157e6ccefbad4b0cd7e549db6696691a70c11b108f26bf6bf76eef26af8c10"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
 ]
 
 [[package]]
@@ -935,6 +1043,12 @@ dependencies = [
  "hashbrown",
 ]
 
+[[package]]
+name = "is_terminal_polyfill"
+version = "1.70.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a6cb138bb79a146c1bd460005623e142ef0181e3d0219cb493e02f7d08a35695"
+
 [[package]]
 name = "itoa"
 version = "1.0.18"
@@ -972,9 +1086,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.186"
+version = "0.2.189"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "68ab91017fe16c622486840e4c83c9a37afeff978bd239b5293d61ece587de66"
+checksum = "3eaf3ede3fee6db1a4c2ee091bf8a8b4dccdc6d17f656fb07896ee72867612f2"
 
 [[package]]
 name = "libredox"
@@ -1057,6 +1171,12 @@ version = "1.21.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
 
+[[package]]
+name = "once_cell_polyfill"
+version = "1.70.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "384b8ab6d37215f3c5301a95a4accb5d64aa607f1fcb26a11b5303878451b4fe"
+
 [[package]]
 name = "option-ext"
 version = "0.2.0"
@@ -1159,28 +1279,22 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.106"
+version = "1.0.107"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8fd00f0bb2e90d81d1044c2b32617f68fcb9fa3bb7640c23e9c748e53fb30934"
+checksum = "985e7ec9bb745e6ce6535b544d84d6cd6f7ad8bd711c398938ae983b91a766d9"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.46"
+version = "1.0.47"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dfbc457d0c7a0759a614551b11a6409e5951f6c7537be1f1b7682b9ae9230368"
+checksum = "1fbf4db142a473a8d80c26bbf18454ed458bf8d26c8219c331daecfdbd079001"
 dependencies = [
  "proc-macro2",
 ]
 
-[[package]]
-name = "r-efi"
-version = "5.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "69cdb34c158ceb288df11e18b4bd39de994f6657d83847bdffdbd7f346754b0f"
-
 [[package]]
 name = "r-efi"
 version = "6.0.0"
@@ -1195,7 +1309,18 @@ checksum = "ba009ff324d1fc1b900bd1fdb31564febe58a8ccc8a6fdbb93b543d33b13ca43"
 dependencies = [
  "getrandom 0.2.17",
  "libredox",
- "thiserror",
+ "thiserror 1.0.69",
+]
+
+[[package]]
+name = "redox_users"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4e608c6638b9c18977b00b475ac1f28d14e84b27d8d42f70e0bf1e3dec127ac"
+dependencies = [
+ "getrandom 0.2.17",
+ "libredox",
+ "thiserror 2.0.19",
 ]
 
 [[package]]
@@ -1229,7 +1354,7 @@ checksum = "36c9dbf50a60c82375e66b61d522c936b187a11b25c0a42e91c516326ad24a4f"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
 ]
 
 [[package]]
@@ -1306,9 +1431,9 @@ checksum = "8a7852d02fc848982e0c167ef163aaff9cd91dc640ba85e263cb1ce46fae51cd"
 
 [[package]]
 name = "serde"
-version = "1.0.228"
+version = "1.0.229"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9a8e94ea7f378bd32cbbd37198a4a91436180c5bb472411e48b5ec2e2124ae9e"
+checksum = "4148590afebada386688f18773da617792bf2ef03ffc1e4cbd2b1d45b023e0ba"
 dependencies = [
  "serde_core",
  "serde_derive",
@@ -1316,29 +1441,29 @@ dependencies = [
 
 [[package]]
 name = "serde_core"
-version = "1.0.228"
+version = "1.0.229"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "41d385c7d4ca58e59fc732af25c3983b67ac852c1a25000afe1175de458b67ad"
+checksum = "67dca2c9c51e58a4791a4b1ed58308b39c64224d349a935ab5039aa360942a48"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.228"
+version = "1.0.229"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d540f220d3187173da220f885ab66608367b6574e925011a9353e4badda91d79"
+checksum = "e7a5d71263a5a7d47b41f6b3f06ba276f10cc18b0931f1799f710578e2309348"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 3.0.3",
 ]
 
 [[package]]
 name = "serde_json"
-version = "1.0.150"
+version = "1.0.151"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e8014e44b4736ed0538adeecded0fce2a272f22dc9578a7eb6b2d9993c74cfb9"
+checksum = "c841b55ecdae098c80dcae9cf767f6f8a0c2cdb3416bbef72181df4d0fe73f14"
 dependencies = [
  "itoa",
  "memchr",
@@ -1349,13 +1474,13 @@ dependencies = [
 
 [[package]]
 name = "serde_repr"
-version = "0.1.20"
+version = "0.1.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "175ee3e80ae9982737ca543e96133087cbd9a485eecc3bc4de9c1a37b47ea59c"
+checksum = "8d3b1629de253c70a0508c3899572da79ca359fdab27c7920ff00406df418906"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 3.0.3",
 ]
 
 [[package]]
@@ -1447,6 +1572,12 @@ dependencies = [
  "float-cmp",
 ]
 
+[[package]]
+name = "strsim"
+version = "0.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
+
 [[package]]
 name = "svgtypes"
 version = "0.16.1"
@@ -1468,6 +1599,17 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "syn"
+version = "3.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "53e9bae58849f64dfa4f5d5ae372c8341f7305f82a3868709269343628b659a3"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
 [[package]]
 name = "system-deps"
 version = "7.0.8"
@@ -1477,7 +1619,7 @@ dependencies = [
  "cfg-expr",
  "heck",
  "pkg-config",
- "toml 1.1.3+spec-1.1.0",
+ "toml 1.1.4+spec-1.1.0",
  "version-compare",
 ]
 
@@ -1506,7 +1648,16 @@ version = "1.0.69"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b6aaf5339b578ea85b50e080feb250a3e8ae8cfcdff9a461c9ec2904bc923f52"
 dependencies = [
- "thiserror-impl",
+ "thiserror-impl 1.0.69",
+]
+
+[[package]]
+name = "thiserror"
+version = "2.0.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09a43598840e33d5b0331f38c5e30d13bb11c11210a4b58f0d9b18a5a5eefcd9"
+dependencies = [
+ "thiserror-impl 2.0.19",
 ]
 
 [[package]]
@@ -1517,7 +1668,18 @@ checksum = "4fee6c4efc90059e10f81e6d42c60a18f76588c3d74cb83a0b242a2b6c7504c1"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "2.0.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "43cbfe0cf76104d42a574802844187e84a305e531ed54455f11fbde0f10541cd"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 3.0.3",
 ]
 
 [[package]]
@@ -1548,9 +1710,9 @@ dependencies = [
 
 [[package]]
 name = "tokio"
-version = "1.53.0"
+version = "1.53.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d988bcd52dbe076d3d46903332f58c912b87a2c49b1428419a5845154762ffee"
+checksum = "202caea871b69668250d242070849eb495be178ed697a3e98aebce5bc81a0bed"
 dependencies = [
  "bytes",
  "libc",
@@ -1571,7 +1733,7 @@ checksum = "6328af13490e73a9b4694030fafd93f8c8c6a9dede33e821c3fc63eddf8042ba"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
 ]
 
 [[package]]
@@ -1588,9 +1750,9 @@ dependencies = [
 
 [[package]]
 name = "toml"
-version = "1.1.3+spec-1.1.0"
+version = "1.1.4+spec-1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "53c96ecdfa941c8fc4fcaed14f99ada8ebed502eef533015095a07e3301d4c3c"
+checksum = "3aace63f4bbcdfc2c965b059de67119c89c4017a70d633be6c104910f67056f5"
 dependencies = [
  "indexmap",
  "serde_core",
@@ -1647,9 +1809,9 @@ dependencies = [
 
 [[package]]
 name = "toml_parser"
-version = "1.1.2+spec-1.1.0"
+version = "1.1.3+spec-1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a2abe9b86193656635d2411dc43050282ca48aa31c2451210f4202550afb7526"
+checksum = "1d38ac1cf9b95face32296c0a3ede1fdc270627c9d9c02a7274dd6d960dc4d56"
 dependencies = [
  "winnow 1.0.4",
 ]
@@ -1685,7 +1847,7 @@ checksum = "7490cfa5ec963746568740651ac6781f701c9c5ea257c58e057f3ba8cf69e8da"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
 ]
 
 [[package]]
@@ -1748,6 +1910,12 @@ dependencies = [
  "xmlwriter",
 ]
 
+[[package]]
+name = "utf8parse"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
+
 [[package]]
 name = "uuid"
 version = "1.24.0"
@@ -1771,15 +1939,6 @@ version = "0.11.1+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ccf3ec651a847eb01de73ccad15eb7d99f80485de043efb2f370cd654f4ea44b"
 
-[[package]]
-name = "wasip2"
-version = "1.0.4+wasi-0.2.12"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b67efb37e106e55ce722a510d6b5f9c17f083e5fc79afc2badeb12cc313d9487"
-dependencies = [
- "wit-bindgen",
-]
-
 [[package]]
 name = "wasm-bindgen"
 version = "0.2.126"
@@ -1812,7 +1971,7 @@ dependencies = [
  "bumpalo",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
  "wasm-bindgen-shared",
 ]
 
@@ -1924,12 +2083,6 @@ dependencies = [
  "memchr",
 ]
 
-[[package]]
-name = "wit-bindgen"
-version = "0.57.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ebf944e87a7c253233ad6766e082e3cd714b5d03812acc24c318f549614536e"
-
 [[package]]
 name = "xml-rs"
 version = "0.8.28"
@@ -1981,7 +2134,7 @@ dependencies = [
  "proc-macro-crate",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
  "zbus_names",
  "zvariant",
  "zvariant_utils",
@@ -2027,7 +2180,7 @@ dependencies = [
  "proc-macro-crate",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.119",
  "zvariant_utils",
 ]
 
@@ -2040,6 +2193,6 @@ dependencies = [
  "proc-macro2",
  "quote",
  "serde",
- "syn",
+ "syn 2.0.119",
  "winnow 1.0.4",
 ]

Cargo.toml

@@ -17,6 +17,8 @@ bread-theme = { git = "https://github.com/Breadway/bread-ecosystem", branch = "d
 # instead of hand-parsing serde_json::Value. See src/widgets/.
 bread-utils = { git = "https://git.breadway.dev/Breadway/bread-ecosystem", branch = "dev", features = ["bread-client"] }
 bread-shared = { git = "https://git.breadway.dev/Breadway/bread", branch = "dev" }
+# Capture primitives for `--screenshot` mode — see src/screenshot.rs.
+bread-screenshots = { git = "https://git.breadway.dev/Breadway/bread-ecosystem", branch = "dev" }
 gtk4 = { version = "0.11", features = ["v4_12"] }
 gtk4-layer-shell = "0.8"
 relm4 = { version = "0.11", features = ["macros"] }
@@ -26,6 +28,8 @@ zbus = { version = "5", default-features = false, features = ["tokio"] }
 tokio = { version = "1", features = ["rt-multi-thread", "macros", "time", "process", "signal", "sync"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+clap = { version = "4", features = ["derive"] }
+anyhow = "1"
 # Pure-Rust SVG rasteriser (default features off → no text/font deps; the icons
 # are vector-only). Needed because librsvg dropped its gdk-pixbuf SVG loader.
 resvg = { version = "0.47", default-features = false }

src/main.rs

@@ -7,6 +7,7 @@ macro_rules! asset {
 mod bar;
 mod notifications;
 mod osd;
+mod screenshot;
 mod theme;
 mod widgets;
 
@@ -124,7 +125,7 @@ pub enum AppInput {
 
 #[relm4::component(pub)]
 impl SimpleComponent for App {
-    type Init = ();
+    type Init = Option<screenshot::ScreenshotRequest>;
     type Input = AppInput;
     type Output = ();
 
@@ -141,7 +142,7 @@ impl SimpleComponent for App {
     }
 
     fn init(
-        _: Self::Init,
+        screenshot_req: Self::Init,
         root: Self::Root,
         sender: ComponentSender<Self>,
     ) -> ComponentParts<Self> {
@@ -644,6 +645,10 @@ impl SimpleComponent for App {
         widgets.center_box.set_center_widget(Some(&center_area));
         widgets.center_box.set_end_widget(Some(&stats_box));
 
+        // Captured before `control_popover` moves into `model` below — needed
+        // by the screenshot dispatch just before this function returns.
+        let control_popover_for_screenshot = control_popover.clone();
+
         let model = App {
             workspaces: vec![],
             active_ws: 1,
@@ -713,6 +718,10 @@ impl SimpleComponent for App {
         notifications::spawn();
         osd::spawn();
 
+        if let Some(req) = screenshot_req {
+            screenshot::dispatch(&root, req, control_popover_for_screenshot);
+        }
+
         ComponentParts { model, widgets }
     }
 
@@ -1411,6 +1420,10 @@ fn stat_label() -> gtk4::Label {
 }
 
 fn main() {
+    use clap::Parser;
+    let cli = screenshot::Cli::parse();
+    let screenshot_req = cli.screenshot_request();
+
     relm4::spawn(async {
         use tokio::signal::unix::{signal, SignalKind};
         let mut stream = signal(SignalKind::hangup()).expect("SIGHUP handler");
@@ -1420,6 +1433,17 @@ fn main() {
         }
     });
 
-    let app = RelmApp::new("sh.breadway.breadbar");
+    // `with_args(vec![])` stops relm4 from handing our own --screenshot/
-    app.run::<App>(());
+    // --output flags to GLib's option parser (`app.run()`'s default), which
+    // would otherwise reject them as unrecognized before Cli::parse() above
+    // ever sees argv. allow_multiple_instances is needed for screenshot runs
+    // specifically: GApplication is single-instance by default, and a normal
+    // breadbar is typically already running, so without this a screenshot
+    // invocation would just activate that existing instance instead of
+    // starting a fresh one whose `init()` receives the request at all.
+    let app = RelmApp::new("sh.breadway.breadbar").with_args(vec![]);
+    if screenshot_req.is_some() {
+        app.allow_multiple_instances(true);
+    }
+    app.run::<App>(screenshot_req);
 }

src/screenshot.rs

@@ -0,0 +1,142 @@
+//! `--screenshot` CLI mode: render a specific view, capture it via
+//! `bread-screenshots`, then exit — driven by `bread-ecosystem`'s
+//! `bread-capture` orchestrator, or run standalone for one-off captures.
+//!
+//! Capture waits on GTK's `map` signal rather than a blind sleep before
+//! grabbing pixels — the surface (or, for popover views, the popover itself)
+//! genuinely isn't on screen yet before that fires, so a fixed delay would
+//! either race a slow first paint or pad every fast one for nothing.
+
+use clap::Parser;
+use gtk4::prelude::*;
+use std::path::PathBuf;
+use std::time::Duration;
+
+/// Extra settle time after `map` for the first frame to actually paint
+/// before grim runs — `map` fires once the surface exists, not once
+/// anything has been drawn into it.
+const SETTLE_DELAY: Duration = Duration::from_millis(300);
+
+/// Settle time for the control-panel view specifically: longer than
+/// [`SETTLE_DELAY`] because the CPU/RAM/PWR/GPU/network labels there aren't
+/// populated by the popover's own load (that only covers volume/brightness/
+/// sinks, see `bar::control::spawn_load`) — they're refreshed by
+/// `bar::stats::spawn_poller`'s 2-second background loop, gated on
+/// `control_popover.is_visible()` at each tick. Capturing any sooner than one
+/// full poll interval after the popover opens leaves them at their initial
+/// placeholder dashes.
+const CONTROL_PANEL_SETTLE_DELAY: Duration = Duration::from_millis(2_200);
+
+/// Delay between the bar's own `map` and calling `popover.popup()`. Calling
+/// `popup()` synchronously from inside the root window's `map` handler
+/// produces a popover that reports itself `map`ped but never actually paints
+/// (confirmed by an independent `grim` capture taken mid-sequence, showing no
+/// popover at all) — presumably the parent widget's own allocation isn't
+/// settled yet at that exact point. Giving the initial layout pass a beat to
+/// finish first is what makes it actually render.
+const PRE_POPUP_DELAY: Duration = Duration::from_millis(300);
+
+#[derive(Parser)]
+#[command(name = "breadbar")]
+pub struct Cli {
+    /// Render the named view, capture it, then exit instead of running
+    /// normally. Known views: "bar", "control-panel".
+    #[arg(long)]
+    pub screenshot: Option<String>,
+
+    /// PNG path to write the capture to. Required together with --screenshot.
+    #[arg(long)]
+    pub output: Option<PathBuf>,
+
+    /// Capture canvas width — matches the isolated compositor's output width
+    /// (`bread-capture --isolate-width`) so the geometry passed to `grim`
+    /// doesn't depend on querying anything at capture time.
+    #[arg(long, default_value_t = 1920)]
+    pub width: u32,
+
+    /// Capture canvas height — see `width`.
+    #[arg(long, default_value_t = 1080)]
+    pub height: u32,
+}
+
+pub struct ScreenshotRequest {
+    pub view: String,
+    pub output: PathBuf,
+    pub width: u32,
+    pub height: u32,
+}
+
+impl Cli {
+    /// `None` for a normal run. Exits the process with an error if
+    /// `--screenshot` was given without `--output`, before any GTK/relm4
+    /// setup happens.
+    pub fn screenshot_request(&self) -> Option<ScreenshotRequest> {
+        let view = self.screenshot.clone()?;
+        let Some(output) = self.output.clone() else {
+            eprintln!("breadbar: --screenshot requires --output");
+            std::process::exit(1);
+        };
+        Some(ScreenshotRequest { view, output, width: self.width, height: self.height })
+    }
+}
+
+/// Wire up the given view's screenshot sequence. Called once from `init()`,
+/// after the window and its popovers exist but before the component finishes
+/// initializing — every path here ends by exiting the process, it never
+/// returns control to the normal bar UI.
+/// The bar's fixed height — matches `root.set_exclusive_zone(32)` /
+/// `set_default_height: 32` in `main.rs`. Unlike the control-panel's full
+/// canvas, this never varies with `--width`/`--height`.
+const BAR_HEIGHT: i32 = 32;
+
+pub fn dispatch(root: &gtk4::ApplicationWindow, req: ScreenshotRequest, control_popover: gtk4::Popover) {
+    match req.view.as_str() {
+        "bar" => {
+            let output = req.output;
+            let width = req.width as i32;
+            root.connect_map(move |_| {
+                let output = output.clone();
+                gtk4::glib::timeout_add_local_once(SETTLE_DELAY, move || {
+                    finish(bread_screenshots::capture_region(0, 0, width, BAR_HEIGHT, &output));
+                });
+            });
+        }
+        "control-panel" => {
+            let output = req.output;
+            let (width, height) = (req.width as i32, req.height as i32);
+            let popover_to_open = control_popover.clone();
+            root.connect_map(move |_| {
+                // Autohide (the default) tries to grab the Wayland seat on
+                // popup, keyed to a real input event's serial — a
+                // programmatic popup() has no such event to grab with.
+                // Screenshot mode never needs the popover to dismiss itself
+                // anyway.
+                popover_to_open.set_autohide(false);
+                let popover_to_open = popover_to_open.clone();
+                gtk4::glib::timeout_add_local_once(PRE_POPUP_DELAY, move || {
+                    popover_to_open.popup();
+                });
+            });
+            control_popover.connect_map(move |_| {
+                let output = output.clone();
+                gtk4::glib::timeout_add_local_once(CONTROL_PANEL_SETTLE_DELAY, move || {
+                    finish(bread_screenshots::capture_region(0, 0, width, height, &output));
+                });
+            });
+        }
+        other => {
+            eprintln!("breadbar: unknown screenshot view '{other}' (known: bar, control-panel)");
+            std::process::exit(1);
+        }
+    }
+}
+
+fn finish(result: anyhow::Result<()>) {
+    match result {
+        Ok(()) => std::process::exit(0),
+        Err(e) => {
+            eprintln!("breadbar: screenshot capture failed: {e}");
+            std::process::exit(1);
+        }
+    }
+}