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Is Mime Detection Routing free to use?

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Who published Mime Detection Routing?

xberg-io (@xberg-io) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Mime Detection Routing by xberg-io — Agent Skill

Name: Mime Detection Routing
Rating: 4.2 (5 reviews)
Author: xberg-io

Mime Detection Routing

MIME type detection and extractor routing in core/mime.rs — the FORMATS registry that EXT_TO_MIME and SUPPORTED_MIME_TYPES are derived from, the path-based and bytes-based detection functions, priority-based registry selection, wildcard MIME families, and the real procedure for adding a format. Load when adding a format, wiring an extractor to a MIME type, or debugging why a file routes to the wrong (or no) extractor.

xberg-io b6483cd 3.9 KB Updated Sep 9, 2026

File contents

MIME Detection & Routing

Detection Flow

Policy -> content and/or extension evidence -> validate_mime_type -> registry.get(mime) -> extractor

Key Functions

Function	Location	Behaviour
`detect_mime_type(path, check_exists: bool)`	`core/mime.rs`	Path-based only — never reads bytes. Lowercased extension → `EXT_TO_MIME`, then tree-sitter extension detection (feature `tree-sitter`), then `mime_guess::from_path`. `check_exists` gates a file-existence check, not content inspection.
`detect_mime_type_from_bytes(bytes)`	`core/mime.rs`	Magic-number detection via the `infer` crate. The only content-sniffing entry point.
`validate_mime_type(mime)`	`core/mime.rs`	Parses the media type, matches its case-insensitive essence against `SUPPORTED_MIME_TYPES`, and returns the registered MIME spelling. Parameters such as `charset` do not affect extractor routing. It does not consult the extractor registry.

The FORMATS registry is the single source of truth

FORMATS: &[FormatEntry { extensions, mime_type, aliases }] in core/mime.rs. EXT_TO_MIME and SUPPORTED_MIME_TYPES are LazyLocks derived from it by iteration — there is no m.insert call site to add to, and hand-editing either is impossible.

The full registry publishes 106 formats, 140 unique extensions, and 53 aliases, verified by scripts/sync_supported_counts.py verify. The published count constants describe that static registry; runtime availability is its intersection with registered extractors. Extension lookup is case-insensitive (the extension is lowercased before the map hit).

Registry Selection

let registry = get_document_extractor_registry();          // plugins/registry/mod.rs
let guard = registry.read()?;
let extractor: Arc<dyn DocumentExtractor> = guard.get(mime_type)?;  // Result, not Option

DocumentExtractorRegistry::get (plugins/registry/extractor.rs) returns the highest-priority() extractor for the MIME type, and returns Err — not None — when none matches.

Wildcard Support

An extractor may register a family: "image/*" matches image/png, image/jpeg, and so on (prefix match on a registered type ending in /*).

Adding a New Format

Add one FormatEntry to FORMATS in crates/xberg/src/core/mime.rs. EXT_TO_MIME and SUPPORTED_MIME_TYPES update automatically.
Run scripts/sync_supported_counts.py sync to update published count claims, then run its verify command.
Implement InternalDocumentExtractor (not DocumentExtractor — see plugin-architecture-patterns) with supported_mime_types() returning the MIME.
Register in crates/xberg/src/extractors/mod.rs::register_default_extractors().

Critical Rules

Call validate_mime_type() before extraction — but do not treat it as proof an extractor exists.
Extension lookup is case-insensitive.
detect_mime_type inspects no content. Extraction defaults to PreferContent, which performs bounded content inspection and falls back to a supported extension. Use ContentOnly when the filename must be ignored; use TrustExtension only for trusted sources.
A specific explicit MIME type is authoritative. application/octet-stream is the exception: it is a generic placeholder and triggers policy-based detection.
Never edit EXT_TO_MIME or SUPPORTED_MIME_TYPES — edit FORMATS.

---name: mime-detection-routingdescription: MIME type detection and extractor routing in core/mime.rs — the FORMATS registry that EXT_TO_MIME and SUPPORTED_MIME_TYPES are derived from, the path-based and bytes-based detection functions, priority-based registry selection, wildcard MIME families, and the real procedure for adding a format. Load when adding a format, wiring an extractor to a MIME type, or debugging why a file routes to the wrong (or no) extractor.--- # MIME Detection & Routing ## Detection Flow ```text Policy -> content and/or extension evidence -> validate_mime_type -> registry.get(mime) -> extractor ``` ## Key Functions | Function | Location | Behaviour | | --- | --- | --- | | `detect_mime_type(path, check_exists: bool)` | `core/mime.rs` | **Path-based only** — never reads bytes. Lowercased extension → `EXT_TO_MIME`, then tree-sitter extension detection (feature `tree-sitter`), then `mime_guess::from_path`. `check_exists` gates a file-existence check, not content inspection. | | `detect_mime_type_from_bytes(bytes)` | `core/mime.rs` | Magic-number detection via the `infer` crate. The only content-sniffing entry point. | | `validate_mime_type(mime)` | `core/mime.rs` | Parses the media type, matches its case-insensitive essence against `SUPPORTED_MIME_TYPES`, and returns the registered MIME spelling. Parameters such as `charset` do not affect extractor routing. It does **not** consult the extractor registry. | ## The FORMATS registry is the single source of truth `FORMATS: &[FormatEntry { extensions, mime_type, aliases }]` in `core/mime.rs`. `EXT_TO_MIME` and `SUPPORTED_MIME_TYPES` are `LazyLock`s **derived** from it by iteration — there is no `m.insert` call site to add to, and hand-editing either is impossible. The full registry publishes 106 formats, 140 unique extensions, and 53 aliases, verified by `scripts/sync_supported_counts.py verify`. The published count constants describe that static registry; runtime availability is its intersection with registered extractors. Extension lookup is case-insensitive (the extension is lowercased before the map hit). ## Registry Selection ```rust let registry = get_document_extractor_registry(); // plugins/registry/mod.rs let guard = registry.read()?; let extractor: Arc<dyn DocumentExtractor> = guard.get(mime_type)?; // Result, not Option ``` `DocumentExtractorRegistry::get` (`plugins/registry/extractor.rs`) returns the highest-`priority()` extractor for the MIME type, and returns `Err` — not `None` — when none matches. ## Wildcard Support An extractor may register a family: `"image/*"` matches `image/png`, `image/jpeg`, and so on (prefix match on a registered type ending in `/*`). ## Adding a New Format 1. Add one `FormatEntry` to `FORMATS` in `crates/xberg/src/core/mime.rs`. `EXT_TO_MIME` and `SUPPORTED_MIME_TYPES` update automatically. 2. Run `scripts/sync_supported_counts.py sync` to update published count claims, then run its `verify` command. 3. Implement `InternalDocumentExtractor` (not `DocumentExtractor` — see `plugin-architecture-patterns`) with `supported_mime_types()` returning the MIME. 4. Register in `crates/xberg/src/extractors/mod.rs::register_default_extractors()`. ## Critical Rules 1. Call `validate_mime_type()` before extraction — but do not treat it as proof an extractor exists. 2. Extension lookup is case-insensitive. 3. `detect_mime_type` inspects no content. Extraction defaults to `PreferContent`, which performs bounded content inspection and falls back to a supported extension. Use `ContentOnly` when the filename must be ignored; use `TrustExtension` only for trusted sources. 4. A specific explicit MIME type is authoritative. `application/octet-stream` is the exception: it is a generic placeholder and triggers policy-based detection. 5. Never edit `EXT_TO_MIME` or `SUPPORTED_MIME_TYPES` — edit `FORMATS`.

Frequently asked questions