issues: a panic is never an accident, the owner's rule as a track, not yet enforced; seven stale crafted-ELF clauses go

Cargo.toml

@@ -207,8 +207,7 @@ opt-level = 2
 # `opt-level = 0`. Nothing fail-fast is traded for it — `opt-level` does not
 # touch `debug-assertions`, which cargo still passes as `on` (checked with
 # `cargo build -p toyos-fat32 -v`), and rustc derives `overflow-checks` from
-# that. The pure crates' hostile-input tests keep both knobs that *found* the
-# two crafted-ELF kernel panics in `issues/`.
+# that.
 #
 # **One member depends on this line for correctness rather than for speed, and
 # its own manifest says so at length — this is the other half of that
@@ -227,9 +226,8 @@ opt-level = 3
 
 # The one profile every guest binary is built with. Optimised, because an
 # unoptimised guest mismeasures everything under TCG;
-# debug-assertions and overflow-checks on, because fail-fast beats speed here
-# and both crafted-ELF kernel panics in `issues/` were *found* by
-# an overflow check. `--release` would turn the last two off silently, so this
+# debug-assertions and overflow-checks on, because fail-fast beats speed here.
+# `--release` would turn the last two off silently, so this
 # build system no longer has the flag.
 #
 # It is declared here rather than in `toyos-ld/Cargo.toml` because cargo

bootloader/Cargo.toml

@@ -41,9 +41,8 @@ uefi-services = { version = "0.23.0", features = ["panic_handler", "logger"] }
 
 # The one profile every guest binary is built with. Optimised, because an
 # unoptimised guest mismeasures everything under TCG;
-# debug-assertions and overflow-checks on, because fail-fast beats speed here
-# and both crafted-ELF kernel panics in `issues/` were *found* by
-# an overflow check. `--release` would turn the last two off silently, so this
+# debug-assertions and overflow-checks on, because fail-fast beats speed here.
+# `--release` would turn the last two off silently, so this
 # build system no longer has the flag.
 [profile.toyos]
 inherits = "dev"

issues/kernel/a-panic-is-never-an-accident.md

@@ -0,0 +1,68 @@
+---
+status: open
+kind: track
+opened: 2026-10-01
+---
+
+# A panic is never an accident: the owner's rule, not yet enforced
+
+| Tier | Rule |
+|---|---|
+| 1. Input boundaries | No panic at all: the set below is forbidden. Where the build allows, each parser's entry point also carries a link-time no-panic proof. |
+| 2. The kernel | No implicit panic: the set is denied. A deliberate stop for a broken internal invariant stays (fail fast), as an `#[expect(…, reason = "…")]` whose reason names the invariant. A type that makes the broken state unrepresentable is preferred over any stop. |
+| 3. System services | The same rule as the kernel. |
+| 4. Apps, ports, test code and build tooling | Normal Rust. |
+
+**The set**, every name checked against clippy 0.1.98 (`48a229ceae`):
+- indexing and slicing: `clippy::indexing_slicing`, and `clippy::string_slice`,
+  because the first does not fire on slicing a `str`;
+- arithmetic: `clippy::arithmetic_side_effects`. `[profile.toyos]` sets
+  `overflow-checks`, so arithmetic is a panicking form;
+- `clippy::unwrap_used`, `clippy::expect_used`, `clippy::panic`,
+  `clippy::unreachable`, `clippy::todo`, `clippy::unimplemented`,
+  `clippy::panic_in_result_fn`;
+- truncating casts: `clippy::cast_possible_truncation`. A truncating `as` does
+  not panic; the owner names it, and for tiers 1 to 3 that overrides its
+  rejection in `issues/build/clippy-stage-two-is-lints-one-at-a-time.md`;
+- standard functions: `clippy::disallowed_methods` naming `slice::split_at` and
+  `slice::copy_from_slice`, and `clippy::disallowed_macros` naming
+  `core::assert`, `core::assert_eq` and `core::assert_ne`.
+
+**Today.** No crate carries the set: none names `string_slice`,
+`panic_in_result_fn`, `todo`, `unimplemented` or `cast_possible_truncation`.
+In `kernel/`, `cargo clippy --target x86_64-unknown-none` with the set as
+warnings reports 2,274 findings, 992 of them `arithmetic_side_effects`, 408
+`indexing_slicing`, 394 `cast_possible_truncation` and 208 `disallowed_macros`.
+
+**Constraints.**
+- The set does not see a shift by a variable amount, `pow` or `abs`, though
+  each panics under `overflow-checks`; nor a standard function it does not
+  name, nor a panic inside a callee.
+- `clippy::allow_attributes` checks outer attributes alone: an inner
+  `#![allow(…, reason = "…")]` passes it and `allow_attributes_without_reason`.
+- `disallowed_methods` and `disallowed_macros` read the nearest `clippy.toml`
+  alone, and the root's reaches every crate beneath it, tier 4 included.
+- The no-panic proof needs unwinding: its README says "The attribute is useless
+  in code built with `panic = "abort"`". Both kernel targets print
+  `"panic-strategy": "abort"` from `rustc -Z unstable-options --print
+  target-spec-json`, so the proof has to come from a host build.
+- `--clippy` lints no userland program, because the `toyos` toolchain ships no
+  clippy (`src/clippy.rs:7-8`).
+
+**Stages, in order.**
+1. Tier 1, one area at a time. The first exit is one declaration of the set
+   that every tier-1 crate reads in place of its own copy. An area's exit is
+   its crate or kernel module forbidding the set under `cargo run -- --clippy`;
+   `forbid` refuses any inner `#[allow]` or `#[expect]` of it, the `#[allow]`
+   in `issues/design-debt/elf-domain-lint-line-not-yet-added.md`'s exit too.
+2. The link-time proof on the parser entry points: works or not, measured. The
+   exit is a step of `cargo run -- --ci host` whose host build refuses to link
+   an entry point with a panicking path, or a `rejected` issue with the
+   measurement.
+3. The kernel, one module at a time. The stage ends when `kernel/src/main.rs`
+   denies the set and forbids `clippy::allow_attributes` and
+   `clippy::allow_attributes_without_reason` under `--clippy`, and a step of
+   `--ci host` refuses an inner `#![allow]`: then every exception is an
+   `#[expect(…, reason = "…")]`, and a bare `#[allow]` fails the gate.
+4. The system services. The first exit is a userland shape in `src/clippy.rs`;
+   a service's exit is its crate root under stage 3's attributes.

kernel/Cargo.toml

@@ -372,9 +372,8 @@ user-writable-gsbase = []
 
 # The one profile every guest binary is built with.
 # Optimised, because an unoptimised guest mismeasures everything under TCG;
-# debug-assertions and overflow-checks on, because fail-fast beats speed here
-# and both crafted-ELF kernel panics in `issues/` were *found* by
-# an overflow check. `--release` would turn the last two off silently, so this
+# debug-assertions and overflow-checks on, because fail-fast beats speed here.
+# `--release` would turn the last two off silently, so this
 # build system no longer has the flag.
 [profile.toyos]
 inherits = "dev"

src/build.rs

@@ -405,10 +405,7 @@ fn config_crates(root: &Path, config: &SystemConfig) -> Vec<ConfigCrate> {
 /// it in.
 ///
 /// One name, passed to every `cargo build` here and declared by every crate
-/// root the image is made of. `--release` used to be a flag on `cargo run`, and
-/// it silently turned `debug-assertions` and `overflow-checks` off — the two
-/// knobs `issues/`'s crafted-ELF panics were *found* by. There is
-/// no longer a second profile to pick, which is why there is no longer a flag.
+/// root the image is made of.
 pub const PROFILE: &str = "toyos";
 
 /// What every guest `cargo` and `rustc` here runs with: the toolchain directory
@@ -632,9 +629,7 @@ fn contains_subslice(haystack: &[u8], needle: &[u8]) -> bool {
 /// [`PROFILE`] states them and `--release` is gone from this build system, so
 /// the way they can still be lost is somebody editing `[profile.toyos]`. This
 /// asks the artifact rather than the manifest, which is the only question worth
-/// asking: `issues/`'s two crafted-ELF kernel panics were both
-/// *found* by an overflow check, and one of them had no configuration in which
-/// it was an error return.
+/// asking.
 fn assert_overflow_checked(what: &str, image: &[u8]) {
     let found = contains_subslice(image, OVERFLOW_CHECK_MARKER);
     assert!(

userland/Cargo.toml

@@ -65,9 +65,8 @@ winit = { git = "https://github.com/ToyOSOrg/winit", branch = "toyos-0.30.13" }
 
 # The one profile every guest binary is built with.
 # Optimised, because an unoptimised guest mismeasures everything under TCG;
-# debug-assertions and overflow-checks on, because fail-fast beats speed here
-# and both crafted-ELF kernel panics in `issues/` were *found* by
-# an overflow check. `--release` would turn the last two off silently, so this
+# debug-assertions and overflow-checks on, because fail-fast beats speed here.
+# `--release` would turn the last two off silently, so this
 # build system no longer has the flag.
 #
 # What it replaces here: dependencies at 2 through `package."*"`, doom and the