gemelli

Use when writing Rust that branches on an enum modeling state — a capture pipeline state, a Rotation/Flip mode, or any state-machine variant — to choose behavior or a value, or when adding a variant to such an enum. Also when reaching for an if-let chain, a let-else, matches!, or a `_` wildcard arm to consume an enum you own.

Use when composing or chaining Rust Result values — sequencing multi-step fallible operations, tempted by unwrap()/expect()/panic! on an expected failure, matching a Result mid-pipeline just to rewrap it in Ok/Err, discarding a Result with let _ = ..., or deciding where a Result finally becomes a process exit code or a rendered UI error.

Use when writing or modifying a Rust function with conditional branches — about to nest an if inside an if, write an else after a branch that returns/continues/breaks, thread a `let mut result` through branches to return at the end, or wrap a loop body in a condition.

Use when converting between numeric types in Rust, converting string↔number, or about to write `as` — `x as u32`, usize↔u32 index/pixel math, f64→u32 frame-dimension math, or formatting a value into a String.

Use when authoring or converting Rust types in this webcam-to-Syphon/Spout tool — defining a struct, enum, or function signature for capture devices, frames, rotation/crop/scale options, or pipeline state; typing several correlated fields as Option<T>; or about to reach for String, serde_json::Value, HashMap<String, String>, an over-permissive Vec<u8>, an `as` cast, or unwrap()/expect() to avoid modeling a value.

Use when branching on the prefix of a string with starts_with/strip_prefix (namespaced families like device URI schemes "avf://", "syphon://" or CLI transform tokens "rotate=", "flip=") and the branch count keeps growing, when a starts_with if-chain is hard to test or extend per family, or when adding several new prefix families to an existing dispatcher.

Use when naming or renaming a Rust function, method, struct, enum, trait, or module — especially when a name is heading past three words (ensure_capture_device_present, load_and_apply_config), contains and/or/with/if_missing, or describes several steps at once.