The host jobs build their driver with line tables alone, and the seal's red since 2026-10-05 is accounted for

.claude/agents/reviewer.md

@@ -89,9 +89,9 @@ if it meets the bar above; otherwise it is a NOTE.
 - **Caches.** No gate reads these; a diff that breaks one is a BLOCKER. No workflow uses the
   combined `actions/cache`, which saves too. The host cache has one writer, nightly's `host`,
   and one reader, ci.yml's `host`, on the same `runs-on`, both caching `src/cicache.rs`'s
-  `PATHS` with its `DRIVER` as their
-  `CARGO_TARGET_DIR`, the one variable an `env:` gives either: an `ImageOS` or `ImageVersion`
-  set there outlives an image move. The reader's `restore-keys` is the writer's `key` up to its
+  `PATHS` with its `DRIVER` as their `CARGO_TARGET_DIR` and `line-tables-only` as their
+  `CARGO_PROFILE_DEV_DEBUG`, the two variables an `env:` gives either: an `ImageOS` or
+  `ImageVersion` set there outlives an image move. The reader's `restore-keys` is the writer's `key` up to its
   run id. A job that names the host cache runs `actions/checkout`, its cache step and
   `cargo run -- --ci <job>`, `seal` in the writer and `host` in the reader, and nothing else;
   the reader restores before that step, and the writer saves after it. The save's guard,

.github/workflows/ci.yml

@@ -19,10 +19,12 @@ jobs:
     if: github.event_name == 'merge_group' || github.event.pull_request.draft == false
     runs-on: ubuntu-24.04
     timeout-minutes: 45
-    # The driver's own target, and no step's: it says this job carries the
-    # host cache (src/cicache.rs).
     env:
+      # The driver's own target, and no step's: it says this job carries the
+      # host cache (src/cicache.rs).
       CARGO_TARGET_DIR: target/ci-driver
+      # The writer's: a unit built with other debuginfo is not the entry's.
+      CARGO_PROFILE_DEV_DEBUG: line-tables-only
     steps:
       - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
 

.github/workflows/nightly.yml

@@ -21,10 +21,14 @@ jobs:
   host:
     runs-on: ubuntu-24.04
     timeout-minutes: 90
-    # The driver's own target, and no step's: it says this job carries the
-    # host cache (src/cicache.rs).
     env:
+      # The driver's own target, and no step's: it says this job carries the
+      # host cache (src/cicache.rs).
       CARGO_TARGET_DIR: target/ci-driver
+      # The driver's and every step's: a backtrace in a log reads line tables,
+      # and nothing reads the rest of the debuginfo, of which a Linux link
+      # copies every dependency's into each binary.
+      CARGO_PROFILE_DEV_DEBUG: line-tables-only
     steps:
       - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
         with:

issues/a-host-reader-on-another-runner-image-downloads-the-entry-and-discards-it.md

@@ -0,0 +1,23 @@
+---
+status: open
+kind: tooling
+opened: 2026-10-08
+---
+
+# A host reader on another runner image downloads the entry and discards it
+
+`src/cicache.rs` deletes an entry built on another runner image, and the cache
+key cannot carry the image. GitHub serves two `ubuntu-24.04` images at once
+while it rolls one out: on 2026-10-07 run 37601225884 (09:31Z) and `host`
+readers 37646740767 (15:47Z) and 37687777630 (21:12Z) ran on 20261004.327.1,
+and runs 37685714260 (20:55Z) and 37693139619 (21:59Z) on 20260927.320.1. So
+for the days of a rollout a reader meets an entry of the other image by chance,
+whichever image the writer drew that night: both readers above restored
+1,813,819,887 B, deleted it and ran cold, 15 and 10 minutes of steps against
+the 5 a reader of its own image's entry took in run 37693139619.
+
+Owner: the host cache (`src/cicache.rs`).
+
+**Exit condition.** A reader restores an entry only of its own image, or the
+share of `host` runs that discard one is measured over a rollout and accepted
+here.

issues/a-red-nightly-on-main-is-reported-to-nobody.md

@@ -0,0 +1,23 @@
+---
+status: open
+kind: tooling
+opened: 2026-10-08
+---
+
+# A red nightly on main is reported to nobody
+
+`nightly.yml`'s scheduled run is a check of no pull request and no merge group:
+its verdict blocks nothing, and no role's prompt reads it. Its `host` job, the
+host cache's one writer, was red at its seal on 2026-10-05, 2026-10-06 and
+2026-10-07 (runs 37292450697, 37444133685, 37601225884), after #722 brought
+`gix` into the build system and took the cold tree from 7,605,844,073 B to
+8,540,783,725 B, past the seal's 8,000,000,000 B. The last entry saved is run
+37190643147's, of 2026-10-04. A review of another pull request found the red on
+2026-10-07, three runs in.
+
+Owner: the orchestrator's prompt (`.claude/agents/orchestrator.md`).
+
+**Exit condition.** A red scheduled `nightly` on `main` reaches whoever lands
+work before the next one runs, by a means a reader can name: a sentence in the
+prompt that reads `gh run list --workflow nightly.yml --branch main --limit 1`
+before a landing, or a required check that fails on it.

issues/the-host-caches-limit-reaches-the-10-gb-only-through-one-measured-ratio.md

@@ -22,6 +22,28 @@ it. With that one set the ratio may fall to 1.76 before 2H + T reaches 10 GB.
 The lowest measured is 3.08: run 36844536500
 sealed 9553 MiB on macOS and saved 3,250,736,567 B.
 
+Two more Linux ratios, both above it: run 37190643147 (d47b383cf) sealed
+7,605,844,073 B and saved 1,813,819,887 B, 4.19; run 37693139619 sealed
+8,608,140,775 B, and `tar | zstd -T0` of its paths held 2,020,684,970 B, 4.26.
+
+T is not one set. On 2026-10-07 the repository's cache list held 10,948,823,786 B
+in 25 entries, past the 10 GB already: one host entry, main's four layers
+(912,484,904 B) and twenty sysroot layers of about 420 MB, one per pull request
+or merge group that moved the sysroot's key. GitHub evicts by last access and
+removes an entry unread for seven days, so what goes first is a layer whose
+pull request has merged; nothing here measures that it is.
+
+The seal counts more than the save stores. A hard link is counted once per
+name, and `tar` stores its bytes once: in run 37693139619 the driver's binary
+(262,085,512 B), the build system's and the harness's binaries under
+`target/debug` (150,775,984 B) and the apps under `userland/target`
+(108,795,168 B) were each counted twice, 521,656,664 B of the 8,608,140,775 B.
+
+The entry stores files every read rewrites: the driver's binary and its path
+crates' libraries, 414,270,068 B in that run with the driver's full debuginfo,
+since a checkout dates every source after the entry and cargo builds the driver
+before the read.
+
 No gate reads a stored size. If the targets compress worse, H moves toward the
 floor and nothing reds.
 
@@ -40,4 +62,6 @@ Owner: the host cache (`src/cicache.rs`).
   toolchain layer's from the repository's cache list, and fails when 2H + T
   passes 10 GB;
 - the merge queue's `host` reds a landing whose cold tree passes `LIMIT`,
-  before `main` moves.
+  before `main` moves;
+- the seal counts a file's bytes once however many names it has, and the entry
+  holds no file every read rewrites.

src/ci.rs

@@ -654,10 +654,6 @@ fn carry() {
     // No incremental state: it is most of an entry's bytes, and after a read
     // by content it helps only a crate whose bytes changed.
     std::env::set_var("CARGO_INCREMENTAL", "0");
-    // Line tables alone: a backtrace in a step's log reads them, and nothing
-    // reads the rest of the debuginfo, of which a Linux link copies every
-    // dependency's into each test binary.
-    std::env::set_var("CARGO_PROFILE_DEV_DEBUG", "line-tables-only");
 }
 
 /// Every app the images ship, judged for `os` with the features its image
@@ -1038,8 +1034,8 @@ mod tests {
     const FIXTURE: &str = "TOYOS_CI_TEST_FIXTURE";
 
     /// What a job that carries the cache hands its driver reaches no step: each
-    /// builds in its own workspace's target, with no incremental state and line
-    /// tables alone. The driver is a process of its own, because `carry`
+    /// builds in its own workspace's target, with no incremental state.
+    /// The driver is a process of its own, because `carry`
     /// writes the environment, which no other thread may read meanwhile.
     #[test]
     fn a_step_of_a_job_that_carries_the_cache_builds_in_its_own_target() {
@@ -1052,7 +1048,6 @@ mod tests {
             .env(FIXTURE, fixture.path())
             .env("CARGO_TARGET_DIR", cicache::DRIVER)
             .env_remove("CARGO_INCREMENTAL")
-            .env_remove("CARGO_PROFILE_DEV_DEBUG")
             .output()
             .expect("run the driver");
         let said = String::from_utf8_lossy(&out.stdout).into_owned() + &String::from_utf8_lossy(&out.stderr);
@@ -1075,7 +1070,7 @@ mod tests {
         assert_eq!(metadata["target_directory"].as_str().map(Path::new), Some(ours.as_path()));
         let build = String::from_utf8(cargo(&["build", "-v", "--offline"]).stderr).unwrap();
         let rustc = build.lines().find(|l| l.contains("--crate-name one")).unwrap_or_else(|| panic!("{build}"));
-        assert!(!rustc.contains("-C incremental") && rustc.contains("-C debuginfo=line-tables-only"), "{rustc}");
+        assert!(!rustc.contains("-C incremental"), "{rustc}");
     }
 
     fn repo_root() -> PathBuf {