mcpserver

package
v0.155.0 Latest Latest
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 Go to latest Published: Nov 12, 2026 License: Apache-2.0 Imports: 27 Imported by: 0

Documentation

Overview

Package mcpserver exposes selected reads of a separately running local DataTug agent over MCP. It owns neither the agent process nor its policy session.

Index

Constants

View Source 
const AgentHeader = "X-DataTug-Agent"

AgentHeader declares an agent context to the local agent. The context is self-declared: local masking is accident prevention for honest agents.

View Source 
const (
	DefaultAgentURL = "http://127.0.0.1:8989"
)

Variables

This section is empty.

Functions

func New 

func New(client *Client, version string) *mcp.Server

New builds the MCP server. The SDK handles protocol negotiation and framing.

func Run 

func Run(ctx context.Context, client *Client, version string, in io.ReadCloser, out io.WriteCloser) error

Run serves newline-delimited protocol JSON until stdin closes or ctx ends. The caller owns these streams; no startup text or agent links are printed.

Types

type Client 

type Client struct {
	// contains filtered or unexported fields
}

Client deliberately has no exported HTTP passthrough or configurable transport.

func NewClient 

func NewClient(address string) (*Client, error)

NewClient is the MCP client: MCP is always an agent context, so every request it makes carries AgentHeader.

func NewCommandClient added in v0.142.0 

func NewCommandClient(address string, agent bool) (*Client, error)

NewCommandClient is NewClient for CLI commands, which declare an agent context only when asked to (agent is true).

It accepts only a literal loopback address or localhost, with no path, credentials, query or fragment. Proxies and redirects are disabled: a redirect to another port must never receive the original agent's bearer token.

func (*Client) ChangeLabel added in v0.142.0 

func (c *Client) ChangeLabel(ctx context.Context, scope MeaningScope, ifRevision string, change meaninglabels.Change) (LabelChangeResult, error)

ChangeLabel applies one label change at ifRevision. With an agent context the local agent accepts only propose.

func (*Client) Close 

func (c *Client) Close()

Close releases idle HTTP connections; the separately owned agent keeps running.

func (*Client) DescribeMeaning added in v0.142.0 

func (c *Client) DescribeMeaning(ctx context.Context, scope MeaningScope) (MeaningDescription, error)

DescribeMeaning answers what a source's tables and columns mean, how they join and which are sensitive, in one call. It never returns values.

func (*Client) FindMeaning added in v0.142.0 

func (c *Client) FindMeaning(ctx context.Context, scope MeaningScope, text string) (MeaningMatches, error)

FindMeaning finds the tables and columns whose names, entities or fields match text (1–200 characters).

func (*Client) MeaningLabels added in v0.142.0 

func (c *Client) MeaningLabels(ctx context.Context, scope MeaningScope) (LabelsList, error)

MeaningLabels lists every effective label of a source, with the stored label document and its revision.

func (*Client) ReadTable added in v0.142.0 

func (c *Client) ReadTable(ctx context.Context, in TableReadRequest) (TableRead, error)

ReadTable reads one table through the agent's structured read boundary: labelled columns come back masked (null cells) with their protection.

type Condition added in v0.142.0 

type Condition struct {
	Column string `json:"column" jsonschema:"Column name from datatug_describe_meaning; a masked column is refused"`
	Op     string `json:"op" jsonschema:"One of =, !=, <, <=, >, >="`
	Value  any    `json:"value" jsonschema:"A JSON string, number or boolean"`
}

Condition is one structured-read filter; Value is a JSON string, number or boolean.

type EffectiveLabel added in v0.142.0 

type EffectiveLabel struct {
	Class         string `json:"class,omitempty"`
	Kind          string `json:"kind,omitempty"`
	Origin        string `json:"origin,omitempty"`
	State         string `json:"state,omitempty"`
	Rule          string `json:"rule,omitempty"`
	Revealable    bool   `json:"revealable"`
	NonRevealable bool   `json:"nonRevealable"`
}

EffectiveLabel is a column's effective sensitivity label.

type FieldMeaning added in v0.142.0 

type FieldMeaning struct {
	Entity      string `json:"entity,omitempty"`
	Field       string `json:"field,omitempty"`
	Title       string `json:"title,omitempty"`
	Provenance  string `json:"provenance,omitempty"`
	Description string `json:"description,omitempty"`
}

FieldMeaning is the semantic-layer meaning a table or column maps to.

type ForeignKey added in v0.142.0 

type ForeignKey struct {
	Columns    []string `json:"columns"`
	RefTable   TableRef `json:"refTable"`
	RefColumns []string `json:"refColumns"`
}

ForeignKey is a declared foreign key of a described table.

type JoinEnd added in v0.142.0 

type JoinEnd struct {
	Table   string   `json:"table"`
	Columns []string `json:"columns"`
}

JoinEnd is one side of a join.

type LabelChangeResult added in v0.142.0 

type LabelChangeResult struct {
	Revision string              `json:"revision"`
	Event    meaninglabels.Event `json:"event"`
}

LabelChangeResult is the meanings/labels/change answer.

type LabelsColumn added in v0.142.0 

type LabelsColumn struct {
	Name  string          `json:"name"`
	Type  string          `json:"type"`
	Label *EffectiveLabel `json:"label,omitempty"`
}

LabelsColumn is one column in the meanings/labels answer.

type LabelsList added in v0.142.0 

type LabelsList struct {
	Revision string                 `json:"revision"`
	Tables   []LabelsTable          `json:"tables"`
	Stored   meaninglabels.Document `json:"stored"`
}

LabelsList is the meanings/labels answer.

type LabelsTable added in v0.142.0 

type LabelsTable struct {
	Schema   string         `json:"schema"`
	Name     string         `json:"name"`
	Kind     string         `json:"kind"`
	Reviewed bool           `json:"reviewed"`
	Columns  []LabelsColumn `json:"columns"`
}

LabelsTable is one table in the meanings/labels answer.

type MeaningColumn added in v0.142.0 

type MeaningColumn struct {
	Name     string          `json:"name"`
	Type     string          `json:"type"`
	Nullable *bool           `json:"nullable,omitempty"`
	Meaning  *FieldMeaning   `json:"meaning,omitempty"`
	Label    *EffectiveLabel `json:"label,omitempty"`
}

MeaningColumn is one column of a described table.

type MeaningDescription added in v0.142.0 

type MeaningDescription struct {
	Source         string         `json:"source"`
	LabelsRevision string         `json:"labelsRevision"`
	Notice         string         `json:"notice,omitempty"`
	Tables         []MeaningTable `json:"tables"`
	Joins          []MeaningJoin  `json:"joins"`
}

MeaningDescription is the meanings/describe answer. It contains no values.

type MeaningJoin added in v0.142.0 

type MeaningJoin struct {
	From       JoinEnd `json:"from"`
	To         JoinEnd `json:"to"`
	Provenance string  `json:"provenance"`
}

MeaningJoin is a join implied by a foreign key or by shared meaning.

type MeaningMatch added in v0.142.0 

type MeaningMatch struct {
	Table   string          `json:"table"`
	Column  string          `json:"column,omitempty"`
	Type    string          `json:"type,omitempty"`
	Label   *EffectiveLabel `json:"label,omitempty"`
	Meaning *FieldMeaning   `json:"meaning,omitempty"`
}

MeaningMatch is one meanings/find match.

type MeaningMatches added in v0.142.0 

type MeaningMatches struct {
	Matches []MeaningMatch `json:"matches"`
}

MeaningMatches is the meanings/find answer.

type MeaningScope added in v0.142.0 

type MeaningScope struct {
	Project     string
	Environment string
	Source      string
	Tables      []string
}

MeaningScope names one source and, optionally, the tables to narrow to.

type MeaningTable added in v0.142.0 

type MeaningTable struct {
	Schema      string          `json:"schema"`
	Name        string          `json:"name"`
	Kind        string          `json:"kind"`
	Reviewed    bool            `json:"reviewed"`
	Meanings    []FieldMeaning  `json:"meanings"`
	PrimaryKey  []string        `json:"primaryKey"`
	Columns     []MeaningColumn `json:"columns"`
	ForeignKeys []ForeignKey    `json:"foreignKeys"`
}

MeaningTable is one table or view of a described source.

type Order added in v0.142.0 

type Order struct {
	Column string `json:"column" jsonschema:"Column name; a masked column is refused"`
	Desc   bool   `json:"desc,omitempty" jsonschema:"Sort descending"`
}

Order is one structured-read sort key.

type RawRecordset added in v0.142.0 

type RawRecordset struct {
	Columns []apicontract.Column `json:"columns"`
	Rows    [][]json.RawMessage  `json:"rows"`
}

RawRecordset keeps every cell exactly as the agent returned it. A masked column's cells are null.

type TableRead added in v0.142.0 

type TableRead struct {
	Recordset   RawRecordset                        `json:"recordset"`
	Limitations []apicontract.Limitation            `json:"limitations"`
	Provenance  apicontract.Provenance              `json:"provenance"`
	Truncated   bool                                `json:"truncated"`
	Protection  map[string]meaninglabels.Protection `json:"protection,omitempty"`
	Notice      string                              `json:"notice,omitempty"`
}

TableRead is the records/read answer.

type TableReadRequest added in v0.142.0 

type TableReadRequest struct {
	Project     string
	Environment string
	Source      string
	Schema      string
	Table       string
	Columns     []string
	Where       []Condition
	OrderBy     []Order
	Limit       int
	// Reveal names revealable columns a person reveals for this read only
	// ("*" for every revealable column). The agent refuses it for an agent.
	Reveal []string
}

TableReadRequest is a structured table read through the masking boundary.

type TableRef added in v0.142.0 

type TableRef struct {
	Schema string `json:"schema"`
	Name   string `json:"name"`
}

TableRef names a table.

Source Files

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