Crate schemaui

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schemaui turns JSON Schema documents into fully interactive terminal UIs powered by ratatui, crossterm, and jsonschema.

The library parses rich schemas (nested sections, $ref, arrays, key/value maps, pattern properties…) into a navigable form tree, renders it as a keyboard-first editor, and validates the result after every edit so users always see the full list of issues before saving.

CLI available: schemaui-cli installs the schemaui binary. Prefer the CLI? Jump to CLI installation and usage.

§Feature Highlights

Schema fidelity – draft-07 compatible, including $ref, definitions, patternProperties, enums, numeric ranges, and nested objects/arrays.
Sections & overlays – top-level properties become root tabs, nested objects are flattened into sections, and complex nodes (composites, key/value collections, array entries) open dedicated overlays with their own validators.
Immediate validation – every keystroke can trigger jsonschema::Validator, and all errors (field-scoped + global) are collected and displayed together.
Pluggable I/O – io::input ingests JSON/YAML/TOML (feature-gated) while io::output can emit to stdout and/or multiple files in any enabled format.
Batteries-included CLI – schemaui-cli offers the same pipeline as the library, including multi-destination output, stdin/inline specs, and aggregated diagnostics.
Embedded Web UI – enabling the web feature bundles a browser UI and exposes helpers under schemaui::web::session so host applications can serve the experience without reimplementing the stack.

§Config Schema Auto-Detection

When you launch the CLI with --config and omit --schema, schemaui-cli now resolves the schema in this order:

Explicit --schema
A schema declaration embedded in the config document
Fallback inference via schema_from_data_value

Supported declarations:

JSON: root $schema
TOML: #:schema ./schema.json
YAML: # yaml-language-server: $schema=...
YAML fallback: # @schema ...

Both local and remote schema references are supported. Relative local paths are resolved against the config file directory, while inline/stdin configs fall back to the current working directory. JSON $schema metadata is stripped from the in-memory defaults before validation/output so editor hints do not leak into the final config payload.

Remote http(s) schema loading exists only in schemaui-cli, and the CLI enables the remote-schema feature by default. Disable it if you want a local-only binary surface; the schemaui library crate does not enable any remote schema loading by default.

Feature defaults are intentionally split by audience:

schemaui-cli defaults to the convenient, batteries-included path: TUI + Web + remote schema loading.
schemaui defaults to tui + json, so library consumers keep JSON support without pulling in Web or remote/network-related surface area by default.
json, yaml, and toml are real code-level gates. Keep at least one of them enabled; disabling all three triggers a clear compile-time error.

References:

JSON Schema $schema: https://json-schema.org/understanding-json-schema/reference/schema
Taplo directives (#:schema): https://taplo.tamasfe.dev/configuration/directives.html
YAML language server modeline: https://github.com/redhat-developer/yaml-language-server

§Quick Start

[dependencies]
schemaui = "0.8.0"
serde_json = "1"

use schemaui::prelude::*;
use serde_json::json;

fn main() -> color_eyre::Result<()> {
    color_eyre::install()?;
    let schema = json!({
        "$schema": "http://json-schema.org/draft-07/schema#",
        "title": "Service Runtime",
        "type": "object",
        "properties": {
            "metadata": {
                "type": "object",
                "properties": {
                    "serviceName": {"type": "string"},
                    "environment": {
                        "type": "string",
                        "enum": ["dev", "staging", "prod"]
                    }
                },
                "required": ["serviceName"]
            },
            "runtime": {
                "type": "object",
                "properties": {
                    "http": {
                        "type": "object",
                        "properties": {
                            "host": {"type": "string", "default": "0.0.0.0"},
                            "port": {"type": "integer", "minimum": 1024, "maximum": 65535}
                        }
                    }
                }
            }
        },
        "required": ["metadata", "runtime"]
    });

    let options = UiOptions::default();
    let ui = SchemaUI::new(schema)
        .with_title("SchemaUI Demo")
        .with_options(options.clone());
    let frontend = TuiFrontend { options };
    let value = ui.run_with_frontend(frontend)?;
    println!("{}", serde_json::to_string_pretty(&value)?);
    Ok(())
}

§Public API surface

For library integrations, the main entry points are:

TUI runtime: crate::tui::app::{SchemaUI, UiOptions} and crate::tui::session::TuiFrontend
TUI state: crate::tui::state::* (for example FormState, FormCommand, FormEngine, SectionState)
Schema backend: crate::ui_ast::build_ui_ast together with crate::tui::model::form_schema_from_ui_ast (builds FormSchema from the canonical UI AST)

§Architecture Snapshot

┌─────────────┐   parse/merge    ┌───────────────┐   layout + typing      ┌───────────────┐
│ io::input   ├─────────────────▶│ schema        ├───────────────────────▶│ tui::state    │
└─────────────┘                  │ (loader /     │                        │ (FormState,   │
                                 │ resolver /    │                        │ sections,     │
┌─────────────┐   emit Value     │ build_form_   │   FormSchema           │ reducers)     │
│ io::output  ◀──────────────────┴────pipeline───┘                        └────────┬──────┘
└─────────────┘                                                      focus/edits│
                                                                                │
                                                                     ┌──────────▼──────────┐
                                                                     │ tui::app::runtime   │
                                                                     │ (InputRouter,       │
                                                                     │ overlays, status)   │
                                                                     └──────────┬──────────┘
                                                                                │ draw
                                                                     ┌──────────▼──────────┐
                                                                     │ tui::view::*        │
                                                                     │ (ratatui view)      │
                                                                     └─────────────────────┘

This layout mirrors the actual modules under src/, making it easy to map any code change to its architectural responsibility.

§Input & Output Design

io::input::parse_document_str converts JSON/YAML/TOML (via serde_json, serde_yaml, toml) into serde_json::Value. Feature flags (json, yaml, toml) keep dependencies lean, and the same gates also drive DocumentFormat parsing/probing at compile time.
schema_from_data_value/str infers schemas from live configs, injecting draft-07 metadata and defaults so UIs load pre-existing values.
schema_with_defaults merges canonical schemas with user data, propagating defaults through properties, patternProperties, additionalProperties, dependencies, dependentSchemas, arrays, and $ref targets without mutating the original tree.
io::output::OutputOptions encapsulates serialization format, pretty/compact toggle, and a vector of OutputDestination::{Stdout, File}. Multiple destinations are supported; conflicts are caught before emission.
SchemaUI::with_output wires these options into the runtime so the final serde_json::Value can be written automatically after the session ends.

§Web UI Mode

The optional web feature bundles the files under web/dist/ directly into the crate and exposes high-level helpers for hosting the browser UI. Basic usage:

use schemaui::web::session::{
    ServeOptions,
    WebSessionBuilder,
    bind_session,
};

let schema = serde_json::json!({
    "$schema": "http://json-schema.org/draft-07/schema#",
    "type": "object",
    "properties": {
        "host": {"type": "string", "default": "127.0.0.1"},
        "port": {"type": "integer", "default": 8080}
    },
    "required": ["host", "port"]
});

let config = WebSessionBuilder::new(schema)
    .with_title("Service Config")
    .build()?;
let session = bind_session(config, ServeOptions::default()).await?;
println!("visit http://{}/", session.local_addr());
let value = session.run().await?;
println!("final JSON: {}", serde_json::to_string_pretty(&value)?);

The helper spawns an Axum router that exposes /api/session, /api/save, and /api/exit alongside the embedded static assets. Library users can either call bind_session/serve_session for a turnkey flow or reuse session_router/WebSessionBuilder to integrate the UI into an existing HTTP stack. The official CLI (schemaui-cli web …) is merely a thin wrapper around these APIs.

§JSON Schema → TUI Mapping

build_ui_ast resolves the schema into the canonical UI AST, and form_schema_from_ui_ast maps that tree into FormSection/FieldSchema for the TUI runtime:

Schema feature	Resulting control
`type: string`, `integer`, `number`	Inline text editors with numeric guards
`type: boolean`	Toggle/checkbox
`enum`	Popup selector (single or multi-select for array enums)
Arrays	Inline list summary + overlay editor per item
`patternProperties`, `propertyNames`, `additionalProperties`	Key/Value editor with schema-backed validation
`$ref`, `definitions`	Resolved before layout; treated like inline schemas
`oneOf` / `anyOf`	Variant chooser + overlay form, keeps inactive variants out of the final payload

Root objects spawn tabs; nested objects become sections with breadcrumb titles. Every field records its JSON pointer (for example /runtime/http/port) so focus management and validation can map errors back precisely.

§Validation Lifecycle

jsonschema::validator_for compiles the complete schema once when SchemaUI::run begins.
Each edit dispatches FormCommand::FieldEdited. FormEngine rebuilds the current document via FormState::try_build_value, runs the validator, and feeds errors back into FieldState or the global status line.
Overlays (composite variants, key/value maps, list entries) spin up their own validators built from the sub-schema currently being edited. Nested overlays live on a stack, so each level validates in place before changes flow back to the parent form.

┌─────────────┐ parse schema ┌─────────────────┐ inflate state  ┌────────────┐
│ SchemaUI::run├────────────▶│ domain::parse   ├───────────────▶│ FormState  │
└─────┬───────┘              │ (schema::layout)│                └─────┬──────┘
      │ validator_for()      └─────────────────┘                edits │
      │                                                        ┌──────▼─────────┐
      └────────────────────────────────────────────────────── ▶│ app::runtime   │
                                                               │ (status, input)│
                                                               └──────┬─────────┘
                                                                      │ FormCommand
                                                               ┌──────▼──────────┐
                                                               │ FormEngine      │
                                                               │ + jsonschema    │
                                                               └─────────────────┘

App is the sole owner of FormState; even overlay edits flow through FormEngine so validation rules stay centralized.

§TUI Building Blocks & Shortcuts

Single source for shortcuts – keymap/default.keymap.json lists every shortcut (context, combos, action). The app::keymap::keymap_source!() macro pulls this file into the binary, InputRouter uses it to classify KeyEvents, and the runtime footer renders help text from the same data—keeping docs and behavior DRY.
Root tabs & sections – focus cycles with Ctrl+J / Ctrl+L (roots) and Ctrl+Tab / Ctrl+Shift+Tab (sections). Ordinary Tab/Shift+Tab walk individual fields.
Fields – render labels, descriptions, and inline error messages. Enum/composite fields show the current selection; arrays summarize length and selected entry.
Popups & overlays – pressing Enter opens a popup for enums/oneOf selectors; Ctrl+E pushes a full-screen overlay editor for composites, key/value pairs, and array items. Overlays expose collection shortcuts (Ctrl+N, Ctrl+D, Ctrl+←/→, Ctrl+↑/↓), Ctrl+S saves the active level without closing, and Esc / Ctrl+Q pops a single overlay.
Status & help – the footer highlights dirty state, outstanding validation errors, and context-aware help text. When auto-validate is enabled, each edit updates these counters immediately.

§Generated shortcut reference

§Default context

Shortcut	Action	Kind
`Tab` / `Down`	Next field	`command`
`BackTab` / `Up`	Previous field	`command`
`Ctrl+Tab`	Next section	`command`
`Ctrl+Shift+Tab`	Previous section	`command`
`Ctrl+L`	Next root tab	`command`
`Ctrl+J`	Previous root tab	`command`
`Enter`	Open popup / apply selection	`command`
`Ctrl+E`	Open composite editor	`command`
`Ctrl+S`	Save & validate (overlays stay open)	`command`
`Ctrl+Q` / `Ctrl+C`	Quit (confirm if dirty)	`command`
`Esc`	Cancel / clear status (overlays: pop current level)	`command`
`Ctrl+?` / `Ctrl+H`	Show help and error summary	`command`

§Collection context

Shortcut	Action	Kind
`Ctrl+E`	Open composite editor	`command`
`Ctrl+N`	Add entry	`command`
`Ctrl+D`	Remove entry	`command`
`Ctrl+Left`	Select previous entry	`command`
`Ctrl+Right`	Select next entry	`command`
`Ctrl+Up`	Move entry up	`command`
`Ctrl+Down`	Move entry down	`command`
`Ctrl+?` / `Ctrl+H`	Show help and error summary	`command`

§Overlay context

Shortcut	Action	Kind
`Tab` / `Down`	Next field	`command`
`BackTab` / `Up`	Previous field	`command`
`Ctrl+N`	Add entry	`command`
`Ctrl+D`	Remove entry	`command`
`Ctrl+Left`	Select previous entry	`command`
`Ctrl+Right`	Select next entry	`command`
`Ctrl+Up`	Move entry up	`command`
`Ctrl+Down`	Move entry down	`command`
`Ctrl+S`	Save & validate (overlays stay open)	`command`
`Esc`	Cancel / clear status (overlays: pop current level)	`command`
`Ctrl+?` / `Ctrl+H`	Show help and error summary	`command`

§Help context

Shortcut	Action	Kind
`Esc` / `Ctrl+H` / `Ctrl+?`	Close help	`command`
`Tab`	Next error page	`command`
`BackTab`	Previous error page	`command`
`Up` / `k`	Scroll shortcuts up	`command`
`Down` / `j`	Scroll shortcuts down	`command`
`PageUp`	Page shortcuts up	`command`
`PageDown`	Page shortcuts down	`command`
`Home`	Jump shortcuts to top	`command`
`End`	Jump shortcuts to bottom	`command`
`h`	Scroll error text left	`command`
`l`	Scroll error text right	`command`

§Text field context

Shortcut	Action	Kind
`Left`	Move cursor left	`local edit`
`Right`	Move cursor right	`local edit`
`Home`	Jump to line start	`local edit`
`End`	Jump to line end	`local edit`
`Backspace`	Delete previous character	`local edit`
`Delete`	Delete next character	`local edit`
`Ctrl+W`	Delete previous word	`local edit`
`Ctrl+Z`	Undo text edit	`local edit`
`Ctrl+Y`	Redo text edit	`local edit`

§Numeric field context

Shortcut	Action	Kind
`Left`	Step value down	`local edit`
`Right`	Step value up	`local edit`
`Shift+Left`	Fast step value down	`local edit`
`Shift+Right`	Fast step value up	`local edit`
`Backspace`	Delete previous character	`local edit`
`Delete`	Delete next character	`local edit`
`Ctrl+Z`	Undo numeric edit	`local edit`
`Ctrl+Y`	Redo numeric edit	`local edit`

§Keymap system

Put every shortcut into keymap/default.keymap.json, so runtime logic, help overlays, and generated README shortcut references all consume a single source of truth.

Format – each JSON object declares an id, human-readable description, bilingual descriptionZh, contexts (any of "default", "collection", "overlay", "help", "text", "numeric"), an action discriminated union, and a list of textual combos. For example:
```
{
  "id": "list.move.up",
  "description": "Move entry up",
  "descriptionZh": "条目上移",
  "contexts": ["collection", "overlay"],
  "action": { "kind": "ListMove", "delta": -1 },
  "combos": ["Ctrl+Up"]
}
```
Macro + parser – app::keymap::keymap_source!() include_str!s the JSON, once_cell::sync::Lazy parses it once at startup, and each combo is compiled into a KeyPattern (key code, required modifiers, pretty display string).
Integration – InputRouter::classify delegates to keymap::classify_key, which returns the KeyAction embedded in the JSON. keymap::help_text filters bindings by KeymapContext, concatenating snippets used by StatusLine and overlay instructions.
Generated docs – build.rs parses keymap/default.keymap.json and refreshes the shortcut blocks in README.md and README.ZH.md using explicit HTML markers, so normal Cargo builds keep the bilingual reference in sync with runtime behavior.
Extending – to add a shortcut, edit the JSON, choose the contexts that should expose the help text, and wire the resulting KeyAction inside KeyBindingMap if a new semantic command is introduced.

§Runtime Layers

Layer	Module(s)	Responsibilities
Ingestion	`io::input`, `schema::loader`, `schema::resolver`	Parse JSON/TOML/YAML, resolve `$ref`, and normalize metadata.
Layout typing	`ui_ast::build_ui_ast`, `tui::model::form_schema_from_ui_ast`	Produce `FormSchema` (roots/sections/fields) from the canonical UI AST.
Form state	`tui::state::{form_state, section, field}`	Track focus, pointers, dirty flags, coercions, and errors.
Commands & reducers	`tui::state::{actions, reducers}`, `tui::app::validation`	Define `FormCommand`, mutate state, and route validation results.
Runtime controller	`tui::app::{runtime, overlay, popup, status, keymap}`	Event loop, InputRouter dispatch, overlay lifecycle, help text, status updates.
Presentation	`tui::view` and `tui::view::components::*`	Render tabs, field lists, popups, overlays, and footer via `ratatui`.

Each module is kept under ~600 LOC (hard cap 800) to honor the KISS principle and make refactors manageable.

§CLI (`schemaui-cli`)

§Install

The installed binary is always named schemaui, so the normal entry point is schemaui -c ./config.json.

Choose one of the supported channels:

§Cargo (`cargo install`)

Build from crates.io with Cargo.

cargo install schemaui-cli

§Cargo binstall

Fetch prebuilt GitHub release binaries through cargo-binstall.

cargo binstall schemaui-cli

§Homebrew

Install from the repository tap on macOS or Linux.

brew install YuniqueUnic/schemaui/schemaui

§Scoop

Install on Windows from the repository-hosted Scoop manifest.

scoop install https://raw.githubusercontent.com/YuniqueUnic/schemaui/main/packaging/scoop/schemaui-cli.json

§Direct download

Download the matching archive from https://github.com/YuniqueUnic/schemaui/releases/latest, extract schemaui / schemaui.exe, and place it on your PATH.

§winget manifests

Use the versioned manifests in packaging/winget with winget install --manifest <dir>, or submit them upstream to the community repository.

schemaui \
  --schema ./schema.json \
  --config ./defaults.yaml \
  -o - \
  -o ./config.toml ./config.json

┌────────┐  argh args   ┌──────────────┐ read stdin/files ┌─────────────┐
│  CLI   ├─────────────▶│ InputSource  ├─────────────────▶│ io::input   │
└────┬───┘              └──────┬───────┘                  └────┬────────┘
     │ diagnostics             │ schema/default Value          │
┌────▼─────────┐        ┌──────▼──────┐                        |
│Diagnostic    │◀───────┤ FormatHint  │                        │
│Collector     │        └──────┬──────┘                        │
└────┬─────────┘               │ pass if clean                 │
     │                         │                               │
┌────▼────────┐  build options └────────────┐                  │
│Output logic ├────────────────────────────▶│ OutputOptions    │
└────┬────────┘                             └────────────┬─────┘
     │ SchemaUI::new / with_*                        ┌───▼────────┐
     └──────────────────────────────────────────────▶│ SchemaUI   │
                                                     │ (library)  │
                                                     └────────────┘

Inputs – --schema / --config accept file paths, inline payloads, or - for stdin (but not both simultaneously). If only config is provided the CLI infers a schema via schema_from_data_value.
Diagnostics – DiagnosticCollector accumulates format issues, feature flag mismatches, stdin conflicts, and existing output files before execution.
Outputs – -o/--output is repeatable and may mix file paths with - for stdout. When no destination is set, the tool writes to stdout; pass --temp-file <PATH> if you explicitly want a fallback file. Extensions dictate formats; conflicting extensions are rejected.
Flags – --no-pretty toggles compact output, --force/--yes allows overwriting files, and --title wires through to SchemaUI::with_title.
Shell completion – schemaui completion <bash|zsh|fish|nushell> emits completion scripts from the same argh command graph. PowerShell is not exposed yet because upstream argh_complete does not currently ship a PowerShell generator.

§Key Dependencies

Crate	Purpose
`serde`, `serde_json`, `serde_yaml`, `toml`	Parsing and serializing schema/config data.
`schemars`	Draft-07 schema representation used by the `schema` module.
`jsonschema`	Runtime validation for forms and overlays.
`ratatui`	Rendering widgets, layouts, overlays, and footer.
`crossterm`	Terminal events consumed by `InputRouter`.
`indexmap`	Order-preserving maps for schema traversal.
`once_cell`	Lazy parsing of the keymap JSON.
`argh`, `argh_complete`, `color-eyre` (CLI)	Argument parsing, shell completion, and ergonomic diagnostics.

§Documentation Map

README.md – overview + architecture snapshot (source of truth).
README.ZH.md – Chinese overview kept in sync with this README.
docs/en/structure_design.md – detailed schema/layout/runtime design with flow diagrams.
docs/zh/structure_design.md – Chinese mirror of the architecture guide.
docs/en/cli_usage.md – CLI-specific manual (inputs, outputs, piping, samples).
docs/zh/cli_usage.zh.md – Chinese mirror of the CLI usage guide.

§Development

Run cargo fmt && cargo test regularly; most modules embed their tests by include!ing files from tests/ so private APIs stay covered.
Keep modules below ~600 LOC (hard cap 800). Split helpers as soon as behavior grows to keep KISS intact.
Prefer mature crates (serde_*, schemars, jsonschema, ratatui, crossterm) over bespoke code unless the change is trivial.
Update docs/* whenever pipelines, shortcuts, or CLI semantics evolve so user-facing documentation stays truthful.

§References

https://github.com/rjsf-team/react-jsonschema-form
https://ui-schema.bemit.codes/examples

§Roadmap

parse json schema at runtime and generate a TUI
parse json schema at runtime and generate a Web UI
parse json schema at compile time Then generate the code for TUI, expose necessary APIs for runtime.
parse json schema at compile time Then generate the code for Web UI, expose necessary APIs for runtime.
parse json schema at runtime and generate a Interactive CLI
parse json schema at compile time Then generate the code for Interactive CLI, expose necessary APIs for runtime.

Licensed under either of

Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

§Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Happy hacking!

§Star History

Re-exports§

pub use io::DocumentFormat;
pub use io::DocumentFormatProbe;
pub use io::input::parse_document_str;
pub use io::input::schema_from_data_str;
pub use io::input::schema_from_data_value;
pub use io::input::schema_with_defaults;
pub use io::output::OutputDestination;
pub use io::output::OutputOptions;
pub use precompile::TuiArtifacts;
pub use precompile::UiArtifactBundle;

Modules§

io
precompile
prelude
ui_ast

Structs§

CompositeOverlay
FormSchema
LayoutNavModel
PopupRender
SchemaUI
TuiFrontend: TUI frontend implementation that consumes a prepared FrontendContext and runs the interactive terminal UI.
UiContext
UiOptions

Functions§

draw

Crate schemaui

Crate schemaui Copy item path

§Feature Highlights

§Config Schema Auto-Detection

§Quick Start

§Public API surface

§Architecture Snapshot

§Input & Output Design

§Web UI Mode

§JSON Schema → TUI Mapping

§Validation Lifecycle

§TUI Building Blocks & Shortcuts

§Generated shortcut reference

§Default context

§Collection context

§Overlay context

§Help context

§Text field context

§Numeric field context

§Keymap system

§Runtime Layers

§CLI (schemaui-cli)

§Install

§Cargo (cargo install)

§Cargo binstall

§Homebrew

§Scoop

§Direct download

§winget manifests

§Key Dependencies

§Documentation Map

§Development

§References

§Roadmap

§Contributing

§Star History

Re-exports§

Modules§

Structs§

Functions§

Crate schemaui

§CLI (`schemaui-cli`)

§Cargo (`cargo install`)