Crate day_build 

day-build — resource-constant codegen for a Day app’s build.rs (DESIGN.md §18.5).

An app’s build.rs calls generate_resources, which scans the project’s resource/{images,assets,fonts} directories and writes typed symbolic constants to $OUT_DIR/day_resources.rs:

pub mod images { use day::ImageName;
    pub const nav_system: ImageName = ImageName::from_static("nav_system"); }
pub mod assets { use day::AssetName;
    pub const numbers_bin: AssetName = AssetName::from_static("numbers.bin"); }
pub mod fonts  { use day::FontFamily;
    pub const pacifico: FontFamily = FontFamily::from_static("Pacifico"); }

The app surfaces it once (pub mod res { include!(concat!(env!("OUT_DIR"), "/day_resources.rs")); }) and then writes image(res::images::nav_system) — a typo is a compile error and the resource is guaranteed bundled. cargo:rerun-if-changed on each resource dir regenerates when a file is added or removed.

This crate is also the canonical source of the resource-name → identifier rules: the CLI stagers (day-cli/src/resources) reuse sanitize_ident and the derivation helpers here so the string baked into a constant is exactly the name staged into each backend’s native store.

For the same reason it owns permissions: the CLI generates each platform’s permission declarations from that table while day-part-permissions queries the same permissions at runtime, and the two must never disagree (docs/permissions.md).

Modules

permissions

The portable-permission → native-declaration table (docs/permissions.md).

Structs

Entry

A single generated constant: its Rust symbol, the value string it wraps (the wire name the backend resolves by), and the source file (for the doc comment).

FtlCall

One FUNC(...) call in a message value — day lint validates function names and option values across every locale file with this (the shared fluent-syntax parse, like message_keys).

ResourcePlan

The full set of constants to emit, grouped by bucket.

StrEntry

A generated localization function: the Fluent message key (the Rust fn name), its sorted params (each $variable the message references, agreed across all locales), and doc (the reference-locale value text, for the generated doc comment).

StrParam

One generated function parameter: the Fluent $variable name and whether it is used as a number (a plural/select selector or NUMBER() argument) — which types it as IntoNumberFArg instead of IntoFArg, so a string can’t be passed where a plural count is needed.

Functions

function_calls

Every function call in every message of a Fluent resource (parse errors tolerated — the partial resource is walked, matching message_keys).

generate_resources

The build-script entry point: scan resource/{images,assets,fonts} under CARGO_MANIFEST_DIR, emit $OUT_DIR/day_resources.rs, and register the resource dirs for cargo:rerun-if-changed. Returns Err (with a fix hint) on a name that is not portable or a symbol collision — the app build.rs should .expect(...) this so the problem fails the build loudly.

message_keys

The message keys defined in a Fluent source (terms/attributes/comments ignored). Public so the CLI lint (day lint fluent coverage) shares this one fluent-syntax parser with the codegen and the runtime resolver, instead of a hand-rolled line scanner.

plan_resources

Scan and validate a project’s resources into a ResourcePlan (the pure, testable core).

render

Render a plan to the day_resources.rs source text. This file is include!d inside the app’s pub mod res { … }, so the lint waivers are outer attributes on each bucket module (an inner #![…] is not valid at an include! site) and cover a bucket with no constants (unused use).

sanitize_ident

Sanitize a name to the strictest platform identifier rules (Android R / ArkUI): lowercase, only [a-z0-9_], forced leading letter. The canonical copy — the CLI stagers re-export this so the staged native name and the generated constant string agree by construction.