mastercss_preview_directive_format
Create a safe preview for formatting Master CSS directives, or format in-memory content without writing files.
Contract
Format directives in a source buffer or create a file-formatting preview. Content mode returns formatted text directly and does not create an apply token.
Input
Complete input schema
{ "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "context": { "type": "string", "enum": [ "project", "preset" ] }, "content": { "type": "string" }, "filePath": { "type": "string" }, "patterns": { "type": "array", "items": { "type": "string" } }, "range": { "type": "object", "properties": { "start": { "type": "object", "properties": { "line": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 }, "character": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 } }, "required": [ "line", "character" ] }, "end": { "type": "object", "properties": { "line": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 }, "character": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 } }, "required": [ "line", "character" ] } }, "required": [ "start", "end" ] }, "ttlMs": { "type": "integer", "minimum": 1000, "maximum": 3600000 } }}Example
Call mastercss_preview_directive_format from a connected MCP client with these arguments:
{ "content": "@safelist \"background-color:transparent !\";", "filePath": "card.css"}The returned formatted string joins the importance marker to its class without editing a file.
Output
Both modes report files, edits, changed counts, and mode. Content mode includes formatted; file mode includes inputs and preview. Formatting uses the default preset language service and does not load the project manifest.
Every tool returns an object with version: 3, metadata, diagnostics and result. Success payload fields described above live in result.data; failure has result.status: "error" and a required { code, message } error. JSON text equals structuredContent. Tool errors set isError. Metadata records actual context, package/language/binding versions, manifest fingerprint, entries and dependencies; unavailable information is null or an empty array.
Complete output schema
{ "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "version": { "type": "number", "const": 3 }, "metadata": { "type": "object", "properties": { "versions": { "anyOf": [ { "type": "object", "properties": { "languageVersion": { "type": "number" }, "bindingAbiVersion": { "type": "number" }, "packageVersion": { "type": "string" } }, "required": [ "languageVersion", "bindingAbiVersion", "packageVersion" ], "additionalProperties": {} }, { "type": "null" } ] }, "context": { "anyOf": [ { "type": "string", "enum": [ "project", "preset" ] }, { "type": "null" } ] }, "manifestFingerprint": { "type": [ "string", "null" ] }, "entries": { "type": "array", "items": { "type": "string" } }, "dependencies": { "type": "array", "items": { "type": "string" } } }, "required": [ "versions", "context", "manifestFingerprint", "entries", "dependencies" ], "additionalProperties": false }, "diagnostics": { "type": "array", "items": { "type": "object", "properties": { "code": { "type": "string" }, "phase": { "type": "string" }, "severity": { "type": [ "string", "number" ] }, "message": { "type": "string" }, "notes": { "type": "array", "items": { "type": "string" } }, "alternatives": { "type": "array", "items": { "type": "string" } }, "source": { "type": "string" }, "range": { "anyOf": [ { "type": "object", "properties": { "start": { "type": "number" }, "end": { "type": "number" } }, "required": [ "start", "end" ], "additionalProperties": false }, { "type": "object", "properties": { "start": { "type": "object", "properties": { "line": { "type": "number" }, "character": { "type": "number" } }, "required": [ "line", "character" ], "additionalProperties": false }, "end": { "type": "object", "properties": { "line": { "type": "number" }, "character": { "type": "number" } }, "required": [ "line", "character" ], "additionalProperties": false } }, "required": [ "start", "end" ], "additionalProperties": false } ] } }, "required": [ "message" ], "additionalProperties": {} } }, "result": { "oneOf": [ { "type": "object", "properties": { "status": { "type": "string", "const": "success" }, "data": { "type": "object", "properties": { "root": { "type": "string" }, "manifest": { "type": "object", "properties": { "context": { "type": "string", "enum": [ "project", "preset" ] }, "status": { "type": "string", "enum": [ "loaded", "error" ] }, "fingerprint": { "type": [ "string", "null" ] }, "entries": { "type": "array", "items": { "type": "string" } }, "dependencies": { "type": "array", "items": { "type": "string" } }, "versions": { "type": "object", "properties": { "languageVersion": { "type": "number" }, "bindingAbiVersion": { "type": "number" }, "packageVersion": { "type": "string" } }, "required": [ "languageVersion", "bindingAbiVersion", "packageVersion" ], "additionalProperties": {} } }, "required": [ "context", "status", "fingerprint", "entries", "dependencies" ], "additionalProperties": {} }, "mode": { "type": "string", "enum": [ "content", "files" ] }, "files": { "type": "array", "items": { "type": "object", "properties": { "filePath": { "type": "string" }, "languageId": { "type": "string" }, "edits": { "type": "array", "items": { "type": "object", "properties": { "range": { "type": "object", "properties": { "start": { "type": "object", "properties": { "line": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 }, "character": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 } }, "required": [ "line", "character" ], "additionalProperties": false }, "end": { "type": "object", "properties": { "line": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 }, "character": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 } }, "required": [ "line", "character" ], "additionalProperties": false } }, "required": [ "start", "end" ], "additionalProperties": false }, "newText": { "type": "string" } }, "required": [ "range", "newText" ], "additionalProperties": false } }, "changed": { "type": "boolean" }, "beforeBytes": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 }, "afterBytes": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 } }, "required": [ "filePath", "languageId", "edits", "changed", "beforeBytes", "afterBytes" ], "additionalProperties": false } }, "summary": { "type": "object", "properties": { "files": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 }, "changed": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 }, "edits": { "type": "integer", "minimum": 0, "maximum": 9007199254740991 } }, "required": [ "files", "changed", "edits" ], "additionalProperties": false } }, "required": [ "root", "manifest", "mode", "files", "summary" ], "additionalProperties": {} } }, "required": [ "status", "data" ], "additionalProperties": false }, { "type": "object", "properties": { "status": { "type": "string", "const": "error" }, "error": { "type": "object", "properties": { "code": { "type": "string" }, "message": { "type": "string" } }, "required": [ "code", "message" ], "additionalProperties": false } }, "required": [ "status", "error" ], "additionalProperties": false } ] } }, "required": [ "version", "metadata", "diagnostics", "result" ], "additionalProperties": false}Project context and lifecycle
Content mode does not write files or store a token. In file mode, workspace files stay unchanged until mastercss_apply_preview. A nonempty preview stores a token in this server process; expiry, restart, or successful application requires a new preview. An unchanged result has no confirmation token.
The local stdio server uses the workspace passed to --root. Confirm the root and intended CSS entries with mastercss_workspace_info before relying on project-dependent values.
See the MCP workflow guide for client setup and the preview/apply workflow.