feat(resolvemcp): replace per-model tools with fixed meta tools, guarded filter writes and a function registry

Tools: list_tables, describe_table, select_table, insert_into_table, update_table,
delete_from_table, list_functions, call_function. Visibility follows the model rules.
Filter-based update/delete require filters (never dropped silently), cap the matched rows
(MaxWriteRows), support dry_run, and need a single-use confirm token bound to caller, table,
filters, data and the matched rows. RegisterFunction adds Go-callback and SQL-procedure
functions run in a transaction with BeforeCall/AfterCall hooks. Per-model tools and
resources are removed.

fix(pgsql): UPDATE with SET and a multi-placeholder WHERE renumbered the WHERE parameters
wrongly ($1, $2 became $3, $2); shift them in one pass.

pkg/common/adapters/database/pgsql.go

@@ -5,7 +5,9 @@ import (
 	"database/sql"
 	"fmt"
 	"reflect"
+	"regexp"
 	"sort"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -767,6 +769,9 @@ func (p *PgSQLInsertQuery) Scan(ctx context.Context, dest interface{}) (err erro
 	return nil
 }
 
+// placeholderRe matches a numbered SQL parameter such as $12.
+var placeholderRe = regexp.MustCompile(`\$\d+`)
+
 // PgSQLUpdateQuery implements UpdateQuery for PostgreSQL
 type PgSQLUpdateQuery struct {
 	db             *sql.DB
@@ -897,23 +902,17 @@ func (p *PgSQLUpdateQuery) Exec(ctx context.Context) (res common.Result, err err
 		p.tableName,
 		strings.Join(setClauses, ", "))
 
-	// Update WHERE clause parameter numbers to continue after SET parameters
+	// WHERE placeholders were numbered from $1 as the clauses were added; shift every one past
+	// the SET parameters in a single pass (replacing one number at a time would rewrite a
+	// number it had just produced, e.g. "$1, $2" -> "$3, $2").
 	if len(p.whereClauses) > 0 {
+		shift := len(setArgs)
 		updatedWhereClauses := make([]string, 0, len(p.whereClauses))
 		for _, whereClause := range p.whereClauses {
-			// Find and replace parameter placeholders
-			updatedClause := whereClause
-			paramNum := i
-			// Count how many parameters are in this WHERE clause
-			placeholderCount := strings.Count(whereClause, "$")
-			for j := 0; j < placeholderCount; j++ {
-				oldParam := fmt.Sprintf("$%d", j+1)
-				newParam := fmt.Sprintf("$%d", paramNum)
-				updatedClause = strings.Replace(updatedClause, oldParam, newParam, 1)
-				paramNum++
-			}
-			updatedWhereClauses = append(updatedWhereClauses, updatedClause)
-			i = paramNum
+			updatedWhereClauses = append(updatedWhereClauses, placeholderRe.ReplaceAllStringFunc(whereClause, func(m string) string {
+				n, _ := strconv.Atoi(m[1:])
+				return fmt.Sprintf("$%d", n+shift)
+			}))
 		}
 		p.whereClauses = updatedWhereClauses
 	}

pkg/common/adapters/database/pgsql_test.go

@@ -627,3 +627,23 @@ func TestRawSQL(t *testing.T) {
 
 	assert.NoError(t, mock.ExpectationsWereMet())
 }
+
+// WHERE placeholders must be shifted past the SET parameters without rewriting numbers the
+// shift itself produced: "a = ? AND b = ?" must stay in order.
+func TestPgSQLUpdateQuery_WherePlaceholdersAfterSet(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	require.NoError(t, err)
+	defer db.Close()
+
+	mock.ExpectExec(`UPDATE users SET name = \$1 WHERE a = \$2 AND b = \$3 AND "id" IN \(\$4, \$5\)`).
+		WithArgs("n", 10, 20, 7, 8).
+		WillReturnResult(sqlmock.NewResult(0, 2))
+
+	adapter := NewPgSQLAdapter(db)
+	_, err = adapter.NewUpdate().Table("users").SetMap(map[string]interface{}{"name": "n"}).
+		Where("a = ? AND b = ?", 10, 20).
+		Where(`"id" IN (?, ?)`, 7, 8).
+		Exec(context.Background())
+	require.NoError(t, err)
+	require.NoError(t, mock.ExpectationsWereMet())
+}

pkg/common/tx_guard_test.go

@@ -27,12 +27,13 @@ var allowedPoolHookTx = map[string]int{
 	"resolvespec/handler.go":   1,
 	"websocketspec/handler.go": 1,
 	"resolvemcp/handler.go":    4,
+	"resolvemcp/annotation.go": 1, // BeforeHandle context of the annotate tool
+	"resolvemcp/writewhere.go": 1, // BeforeHandle context of filter writes
+	"resolvemcp/functions.go":  1, // BeforeHandle context of call_function
 }
 
 // allowedPoolQuery: statements outside the request path.
-var allowedPoolQuery = map[string]int{
-	"resolvemcp/annotation.go": 2, // tool annotations, not a data request
-}
+var allowedPoolQuery = map[string]int{}
 
 func guardedFiles(t *testing.T) map[string][]string {
 	t.Helper()

pkg/resolvemcp/confirm.go

@@ -0,0 +1,83 @@
+package resolvemcp
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"sync"
+	"time"
+)
+
+// confirmStore holds the single-use confirmation tokens for filter-based writes. It is
+// in-memory: tokens are lost on restart and are not shared between instances, which only costs
+// the client one more preview call.
+type confirmStore struct {
+	mu      sync.Mutex
+	tokens  map[string]confirmEntry
+	now     func() time.Time
+	maxLive int
+}
+
+type confirmEntry struct {
+	user, table, op, binding string
+	expires                  time.Time
+}
+
+func newConfirmStore() *confirmStore {
+	return &confirmStore{tokens: map[string]confirmEntry{}, now: time.Now, maxLive: 10000}
+}
+
+var errConfirmInvalid = NewClientError(CodeInvalidArgument, "confirm_token is invalid or expired; repeat the call without it to get a new preview")
+
+// issue returns a token bound to the caller, table, operation and binding (a hash of the
+// filters, data and matched rows the preview showed).
+func (c *confirmStore) issue(user, table, op, binding string, ttl time.Duration) (string, error) {
+	var b [16]byte
+	if _, err := rand.Read(b[:]); err != nil {
+		return "", err
+	}
+	tok := hex.EncodeToString(b[:])
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	now := c.now()
+	for k, e := range c.tokens {
+		if now.After(e.expires) {
+			delete(c.tokens, k)
+		}
+	}
+	if len(c.tokens) >= c.maxLive {
+		return "", NewClientError(CodeLimitExceeded, "too many pending confirmations; try again later")
+	}
+	c.tokens[tok] = confirmEntry{user: user, table: table, op: op, binding: binding, expires: now.Add(ttl)}
+	return tok, nil
+}
+
+// consume validates and removes a token. Any mismatch (other user, table, operation or
+// changed binding) is the same error, and the token is spent either way.
+func (c *confirmStore) consume(tok, user, table, op, binding string) error {
+	c.mu.Lock()
+	e, ok := c.tokens[tok]
+	delete(c.tokens, tok)
+	now := c.now()
+	c.mu.Unlock()
+	if !ok || now.After(e.expires) || e.user != user || e.table != table || e.op != op || e.binding != binding {
+		return errConfirmInvalid
+	}
+	return nil
+}
+
+// bindingHash fingerprints the parts of a write a confirmation covers.
+func bindingHash(parts ...any) (string, error) {
+	h := sha256.New()
+	for _, p := range parts {
+		b, err := json.Marshal(p)
+		if err != nil {
+			return "", errors.New("cannot fingerprint request")
+		}
+		h.Write(b)
+		h.Write([]byte{0})
+	}
+	return hex.EncodeToString(h.Sum(nil)), nil
+}

pkg/resolvemcp/functions.go

@@ -0,0 +1,280 @@
+package resolvemcp
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"math"
+	"regexp"
+	"sort"
+	"strings"
+	"sync"
+
+	"github.com/bitechdev/ResolveSpec/pkg/common"
+)
+
+// Parameter types a function may declare.
+const (
+	ParamString  = "string"
+	ParamInteger = "integer"
+	ParamNumber  = "number"
+	ParamBoolean = "boolean"
+	ParamObject  = "object"
+	ParamArray   = "array"
+)
+
+// FunctionParam declares one argument of a registered function.
+type FunctionParam struct {
+	Name        string
+	Type        string // one of the Param* constants
+	Description string
+	Required    bool
+}
+
+// FunctionFunc is a Go function callable through call_function. tx is the transaction the call
+// runs in (OnTxBegin already fired on it); args are validated against the declared params.
+type FunctionFunc func(ctx context.Context, tx common.Database, args map[string]any) (any, error)
+
+// Function is a callable registered with Handler.RegisterFunction. Exactly one of Handler (a Go
+// callback) and Procedure (a SQL function called by name) is set.
+type Function struct {
+	Name        string
+	Description string
+	Params      []FunctionParam
+
+	// Handler is the Go callback.
+	Handler FunctionFunc
+	// Procedure is the SQL function to call, optionally schema-qualified. Declared params are
+	// passed positionally in declaration order; an omitted optional param is NULL. Rows
+	// returned are the result.
+	Procedure string
+
+	// Authorize, when set, decides per caller whether the function is listed and callable.
+	// Return nil to allow.
+	Authorize func(ctx context.Context) error
+}
+
+var (
+	functionNameRe = regexp.MustCompile(`^[A-Za-z][A-Za-z0-9_]{0,63}$`)
+	procedureRe    = regexp.MustCompile(`^[A-Za-z_][A-Za-z0-9_]*(\.[A-Za-z_][A-Za-z0-9_]*)?$`)
+	paramNameRe    = regexp.MustCompile(`^[A-Za-z_][A-Za-z0-9_]{0,63}$`)
+)
+
+type functionRegistry struct {
+	mu    sync.RWMutex
+	funcs map[string]Function
+}
+
+// RegisterFunction makes f callable through the call_function meta tool. Only registered
+// functions are callable; there is no way to reach an arbitrary SQL function.
+func (h *Handler) RegisterFunction(f Function) error {
+	if !functionNameRe.MatchString(f.Name) {
+		return fmt.Errorf("resolvemcp: invalid function name %q", f.Name)
+	}
+	if (f.Handler == nil) == (f.Procedure == "") {
+		return fmt.Errorf("resolvemcp: function %q needs exactly one of Handler and Procedure", f.Name)
+	}
+	if f.Procedure != "" && !procedureRe.MatchString(f.Procedure) {
+		return fmt.Errorf("resolvemcp: invalid procedure name %q", f.Procedure)
+	}
+	seen := map[string]bool{}
+	for _, p := range f.Params {
+		if !paramNameRe.MatchString(p.Name) || seen[p.Name] {
+			return fmt.Errorf("resolvemcp: function %q: invalid or duplicate param %q", f.Name, p.Name)
+		}
+		seen[p.Name] = true
+		switch p.Type {
+		case ParamString, ParamInteger, ParamNumber, ParamBoolean, ParamObject, ParamArray:
+		default:
+			return fmt.Errorf("resolvemcp: function %q param %q: unknown type %q", f.Name, p.Name, p.Type)
+		}
+	}
+	h.functions.mu.Lock()
+	defer h.functions.mu.Unlock()
+	if h.functions.funcs == nil {
+		h.functions.funcs = map[string]Function{}
+	}
+	if _, dup := h.functions.funcs[f.Name]; dup {
+		return fmt.Errorf("resolvemcp: function %q already registered", f.Name)
+	}
+	h.functions.funcs[f.Name] = f
+	return nil
+}
+
+func (h *Handler) function(name string) (Function, bool) {
+	h.functions.mu.RLock()
+	defer h.functions.mu.RUnlock()
+	f, ok := h.functions.funcs[name]
+	return f, ok
+}
+
+// visibleFunctions returns the functions the caller may call, sorted by name.
+func (h *Handler) visibleFunctions(ctx context.Context) []Function {
+	h.functions.mu.RLock()
+	out := make([]Function, 0, len(h.functions.funcs))
+	for _, f := range h.functions.funcs {
+		out = append(out, f)
+	}
+	h.functions.mu.RUnlock()
+	sort.Slice(out, func(i, j int) bool { return out[i].Name < out[j].Name })
+	visible := out[:0]
+	for _, f := range out {
+		if f.Authorize == nil || f.Authorize(ctx) == nil {
+			visible = append(visible, f)
+		}
+	}
+	return visible
+}
+
+// validateArgs checks args against the declared params: required present, no undeclared names,
+// types match. The returned map is what the function receives.
+func validateArgs(params []FunctionParam, args map[string]any) (map[string]any, error) {
+	decl := make(map[string]FunctionParam, len(params))
+	for _, p := range params {
+		decl[p.Name] = p
+	}
+	for name := range args {
+		if _, ok := decl[name]; !ok {
+			return nil, invalidArg("unknown argument %q", truncate(name))
+		}
+	}
+	out := make(map[string]any, len(args))
+	for _, p := range params {
+		v, ok := args[p.Name]
+		if !ok || v == nil {
+			if p.Required {
+				return nil, invalidArg("missing required argument %q", p.Name)
+			}
+			continue
+		}
+		if !argMatches(p.Type, v) {
+			return nil, invalidArg("argument %q must be %s", p.Name, p.Type)
+		}
+		out[p.Name] = v
+	}
+	return out, nil
+}
+
+func truncate(s string) string {
+	if len(s) > maxKeyEcho {
+		return s[:maxKeyEcho] + "..."
+	}
+	return s
+}
+
+func argMatches(typ string, v any) bool {
+	switch typ {
+	case ParamString:
+		_, ok := v.(string)
+		return ok
+	case ParamBoolean:
+		_, ok := v.(bool)
+		return ok
+	case ParamNumber:
+		return isNumber(v)
+	case ParamInteger:
+		switch n := v.(type) {
+		case float64:
+			return n == math.Trunc(n) && !math.IsInf(n, 0)
+		case int, int64:
+			return true
+		}
+		return false
+	case ParamObject:
+		_, ok := v.(map[string]any)
+		return ok
+	case ParamArray:
+		_, ok := v.([]any)
+		return ok
+	}
+	return false
+}
+
+func isNumber(v any) bool {
+	switch v.(type) {
+	case float64, int, int64:
+		return true
+	}
+	return false
+}
+
+// callProcedure runs f.Procedure on tx.
+func callProcedure(ctx context.Context, tx common.Database, f Function, args map[string]any) (any, error) {
+	placeholders := make([]string, len(f.Params))
+	values := make([]any, len(f.Params))
+	for i, p := range f.Params {
+		ph := fmt.Sprintf("$%d", i+1)
+		if p.Type == ParamObject || p.Type == ParamArray {
+			ph += "::jsonb"
+		}
+		if v, ok := args[p.Name]; !ok {
+			values[i] = nil
+		} else if p.Type == ParamObject || p.Type == ParamArray {
+			b, err := json.Marshal(v)
+			if err != nil {
+				return nil, invalidArg("argument %q cannot be encoded", p.Name)
+			}
+			values[i] = string(b)
+		} else {
+			values[i] = v
+		}
+		placeholders[i] = ph
+	}
+	var rows []map[string]any
+	query := fmt.Sprintf("SELECT * FROM %s(%s)", f.Procedure, strings.Join(placeholders, ", "))
+	if err := tx.Query(ctx, &rows, query, values...); err != nil {
+		return nil, err
+	}
+	return rows, nil
+}
+
+// executeCall validates and runs a registered function in a transaction: BeforeHandle (auth and
+// rules), Authorize, then OnTxBegin, BeforeCall, the function, AfterCall.
+func (h *Handler) executeCall(ctx context.Context, name string, rawArgs map[string]any) (_ any, retErr error) {
+	defer recoverPanic(&retErr)
+	ctx, cancel := h.callContext(ctx)
+	defer cancel()
+
+	f, ok := h.function(name)
+	if !ok {
+		return nil, invalidArg("unknown function %q", truncate(name))
+	}
+	hookCtx := &HookContext{Context: ctx, Handler: h, Entity: name, Operation: "call_function", Tx: h.db}
+	if err := h.hooks.Execute(BeforeHandle, hookCtx); err != nil {
+		return nil, err
+	}
+	// Same answer for "not authorized" and "does not exist" so names cannot be probed.
+	if f.Authorize != nil && f.Authorize(ctx) != nil {
+		return nil, invalidArg("unknown function %q", truncate(name))
+	}
+	args, err := validateArgs(f.Params, rawArgs)
+	if err != nil {
+		return nil, err
+	}
+	hookCtx.Data = args
+
+	var result any
+	err = h.runInTx(ctx, hookCtx, func(tx common.Database) error {
+		if err := h.hooks.Execute(BeforeCall, hookCtx); err != nil {
+			return err
+		}
+		if m, ok := hookCtx.Data.(map[string]any); ok {
+			args = m
+		}
+		var err error
+		if f.Handler != nil {
+			result, err = f.Handler(ctx, tx, args)
+		} else {
+			result, err = callProcedure(ctx, tx, f, args)
+		}
+		if err != nil {
+			return err
+		}
+		hookCtx.Result = result
+		return h.hooks.Execute(AfterCall, hookCtx)
+	})
+	if err != nil {
+		return nil, err
+	}
+	return result, nil
+}

pkg/resolvemcp/handler.go

@@ -33,6 +33,8 @@ type Handler struct {
 	version    string
 	oauth2Regs []oauth2Registration
 	oauthSrv   *security.OAuthServer
+	functions  functionRegistry
+	confirms   *confirmStore
 }
 
 // NewHandler creates a Handler with the given database, model registry, and config.
@@ -43,9 +45,11 @@ func NewHandler(db common.Database, registry common.ModelRegistry, cfg Config) *
 		hooks:     NewHookRegistry(),
 		mcpServer: server.NewMCPServer("resolvemcp", "1.0.0"),
 		config:    cfg.withDefaults(),
+		confirms:  newConfirmStore(),
 		name:      "resolvemcp",
 		version:   "1.0.0",
 	}
+	registerMetaTools(h)
 	if cfg.EnableAnnotations {
 		registerAnnotationTool(h)
 	}
@@ -165,13 +169,13 @@ func requestBaseURL(r *http.Request) string {
 	return scheme + "://" + r.Host
 }
 
-// RegisterModel registers a model and immediately exposes it as MCP tools and a resource.
+// RegisterModel registers a model. It becomes visible to the fixed meta tools (list_tables,
+// select_table, ...); no per-model tools are created.
 func (h *Handler) RegisterModel(schema, entity string, model interface{}) error {
 	fullName := buildModelName(schema, entity)
 	if err := h.registry.RegisterModel(fullName, model); err != nil {
 		return err
 	}
-	registerModelTools(h, schema, entity, model)
 	return nil
 }
 
@@ -187,7 +191,6 @@ func (h *Handler) RegisterModelWithRules(schema, entity string, model interface{
 	if err := reg.RegisterModelWithRules(fullName, model, rules); err != nil {
 		return err
 	}
-	registerModelTools(h, schema, entity, model)
 	return nil
 }
 

pkg/resolvemcp/hooks.go

@@ -34,6 +34,12 @@ const (
 	BeforeDelete HookType = "before_delete"
 	AfterDelete  HookType = "after_delete"
 
+	// BeforeCall and AfterCall fire inside the transaction of a call_function call.
+	// hookCtx.Entity is the function name, Data the validated arguments (BeforeCall may
+	// replace them) and Result the function's result (AfterCall).
+	BeforeCall HookType = "before_call"
+	AfterCall  HookType = "after_call"
+
 	// OnTxBegin fires once, first, inside every transaction the handler opens
 	// (including the second short transaction for post-commit work). hookCtx.Tx is
 	// the transaction; use it to stamp transaction-local state such as RLS

pkg/resolvemcp/meta.go

@@ -0,0 +1,438 @@
+package resolvemcp
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"sort"
+	"strings"
+
+	"github.com/mark3labs/mcp-go/mcp"
+
+	"github.com/bitechdev/ResolveSpec/pkg/common"
+	"github.com/bitechdev/ResolveSpec/pkg/modelregistry"
+	"github.com/bitechdev/ResolveSpec/pkg/reflection"
+)
+
+// Operation names used by list_tables and the rule checks.
+const (
+	opSelect = "select"
+	opInsert = "insert"
+	opUpdate = "update"
+	opDelete = "delete"
+)
+
+// filterOperators is the operator list shown by describe_table.
+var filterOperators = []string{"=", "!=", ">", ">=", "<", "<=", "like", "ilike", "in", "is_null", "is_not_null"}
+
+// registerMetaTools adds the fixed tool set. Their number does not grow with the models.
+func registerMetaTools(h *Handler) {
+	readOnly := mcp.WithReadOnlyHintAnnotation(true)
+	tableArg := mcp.WithString("table", mcp.Required(), mcp.Description("Table as 'schema.entity' (see list_tables)."))
+	filtersArg := mcp.WithArray("filters", mcp.Description(`Filter objects, e.g. [{"column":"status","operator":"=","value":"active"}]. Combine with "logic_operator": "AND" (default) or "OR". Operators: `+strings.Join(filterOperators, " ")+"."))
+	idArg := mcp.WithString("id", mcp.Description("Primary key of one row. Use either id or filters."))
+	dryRunArg := mcp.WithBoolean("dry_run", mcp.Description("Report how many rows match and a preview of their ids; change nothing."))
+	confirmArg := mcp.WithString("confirm_token", mcp.Description("Token from the preview a filter-based call returns first; the write only happens with it."))
+
+	h.mcpServer.AddTool(mcp.NewTool("list_tables", readOnly,
+		mcp.WithDescription("List the tables you can use and the operations (select, insert, update, delete) allowed on each.")),
+		h.handleListTables)
+
+	h.mcpServer.AddTool(mcp.NewTool("describe_table", readOnly,
+		mcp.WithDescription("Describe a table: columns and types, primary key, relations (preloadable), writable fields, allowed operations and server limits."),
+		tableArg), h.handleDescribeTable)
+
+	h.mcpServer.AddTool(mcp.NewTool("select_table", readOnly,
+		mcp.WithDescription("Read rows from a table. Results are paged: 'limit' defaults to the server default and is capped; use cursor_forward/cursor_backward for deep paging. The total row count is only computed with include_count."),
+		tableArg, idArg, filtersArg,
+		mcp.WithArray("sort", mcp.Description(`Sort objects, e.g. [{"column":"created_at","direction":"desc"}].`)),
+		mcp.WithArray("columns", mcp.Description("Columns to return. Omit for all.")),
+		mcp.WithArray("omit_columns", mcp.Description("Columns to leave out.")),
+		mcp.WithArray("preloads", mcp.Description(`Relations to load, e.g. [{"relation":"orders"}]. See describe_table for the names and the maximum depth.`)),
+		mcp.WithNumber("limit", mcp.Description("Maximum rows to return.")),
+		mcp.WithNumber("offset", mcp.Description("Rows to skip.")),
+		mcp.WithString("cursor_forward", mcp.Description("Primary key of the last row of the current page; requires sort.")),
+		mcp.WithString("cursor_backward", mcp.Description("Primary key of the first row of the current page; requires sort.")),
+		mcp.WithBoolean("include_count", mcp.Description("Also return the total number of matching rows (slower on large tables).")),
+	), h.handleSelect)
+
+	h.mcpServer.AddTool(mcp.NewTool("insert_into_table",
+		mcp.WithDescription("Insert one row (object) or several rows (array, one transaction, capped). Unknown or read-only fields are rejected."),
+		tableArg, mcp.WithObject("data", mcp.Required(), mcp.Description("A row object or an array of row objects.")),
+	), h.handleInsert)
+
+	h.mcpServer.AddTool(mcp.NewTool("update_table",
+		mcp.WithDescription("Update rows. Give an id (one row, applied at once) or filters (several rows: the first call returns a preview and a confirm_token, repeat the call with the token to apply; the number of rows is capped). Only the fields in data are changed; null sets NULL."),
+		tableArg, idArg, filtersArg,
+		mcp.WithObject("data", mcp.Required(), mcp.Description("Fields to change.")),
+		dryRunArg, confirmArg,
+	), h.handleUpdate)
+
+	h.mcpServer.AddTool(mcp.NewTool("delete_from_table",
+		mcp.WithDescription("Delete rows. Give an id (one row, applied at once) or filters (several rows: the first call returns a preview and a confirm_token, repeat the call with the token to delete; the number of rows is capped)."),
+		mcp.WithDestructiveHintAnnotation(true),
+		tableArg, idArg, filtersArg, dryRunArg, confirmArg,
+	), h.handleDelete)
+
+	h.mcpServer.AddTool(mcp.NewTool("list_functions", readOnly,
+		mcp.WithDescription("List the functions you can call with call_function, with their parameters.")),
+		h.handleListFunctions)
+
+	h.mcpServer.AddTool(mcp.NewTool("call_function",
+		mcp.WithDescription("Call a registered function by name with validated arguments (see list_functions). Runs in a transaction."),
+		mcp.WithString("name", mcp.Required(), mcp.Description("Function name.")),
+		mcp.WithObject("arguments", mcp.Description("Arguments by parameter name.")),
+	), h.handleCallFunction)
+}
+
+// --------------------------------------------------------------------------
+// Tables and rules
+// --------------------------------------------------------------------------
+
+// splitTable parses "schema.entity" (or a bare entity).
+func splitTable(table string) (schema, entity string, err error) {
+	table = strings.TrimSpace(table)
+	if table == "" {
+		return "", "", invalidArg("missing required argument: table")
+	}
+	if i := strings.LastIndex(table, "."); i >= 0 {
+		return table[:i], table[i+1:], nil
+	}
+	return "", table, nil
+}
+
+// modelRules returns the rules of a registered model (defaults when the registry keeps none).
+func (h *Handler) modelRules(schema, entity string) modelregistry.ModelRules {
+	if reg, ok := h.registry.(*modelregistry.DefaultModelRegistry); ok {
+		if r, err := reg.GetModelRules(buildModelName(schema, entity)); err == nil {
+			return r
+		}
+	}
+	return modelregistry.DefaultModelRules()
+}
+
+func opsFor(r modelregistry.ModelRules) []string {
+	var ops []string
+	if r.CanRead {
+		ops = append(ops, opSelect)
+	}
+	if r.CanCreate {
+		ops = append(ops, opInsert)
+	}
+	if r.CanUpdate {
+		ops = append(ops, opUpdate)
+	}
+	if r.CanDelete {
+		ops = append(ops, opDelete)
+	}
+	return ops
+}
+
+// resolveTable finds a registered model and checks the rule for op. A model the rules forbid
+// for op is reported like a missing one for reads of the table list, but with a plain
+// "not allowed" here so the agent learns the operation is off, not that it misspelled the name.
+func (h *Handler) resolveTable(args map[string]any, op string) (schema, entity string, err error) {
+	table, _ := args["table"].(string)
+	schema, entity, err = splitTable(table)
+	if err != nil {
+		return "", "", err
+	}
+	if _, err := h.registry.GetModelByEntity(schema, entity); err != nil {
+		return "", "", invalidArg("unknown table %q; see list_tables", truncate(table))
+	}
+	if op != "" {
+		allowed := false
+		for _, o := range opsFor(h.modelRules(schema, entity)) {
+			if o == op {
+				allowed = true
+			}
+		}
+		if !allowed {
+			return "", "", NewClientError(CodeForbidden, fmt.Sprintf("%s is not allowed on %s", op, buildModelName(schema, entity)))
+		}
+	}
+	return schema, entity, nil
+}
+
+func (h *Handler) handleListTables(ctx context.Context, _ mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	type table struct {
+		Table      string   `json:"table"`
+		Operations []string `json:"operations"`
+	}
+	var tables []table
+	for name := range h.registry.GetAllModels() {
+		schema, entity, _ := splitTable(name)
+		if ops := opsFor(h.modelRules(schema, entity)); len(ops) > 0 {
+			tables = append(tables, table{Table: name, Operations: ops})
+		}
+	}
+	sort.Slice(tables, func(i, j int) bool { return tables[i].Table < tables[j].Table })
+	return marshalResult(map[string]any{"success": true, "tables": tables})
+}
+
+func (h *Handler) handleDescribeTable(_ context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	schema, entity, err := h.resolveTable(req.GetArguments(), "")
+	if err != nil {
+		return toolError("describe_table", err), nil
+	}
+	model, err := h.registry.GetModelByEntity(schema, entity)
+	if err != nil {
+		return toolError("describe_table", invalidArg("unknown table")), nil
+	}
+	rules := h.modelRules(schema, entity)
+	if len(opsFor(rules)) == 0 {
+		return toolError("describe_table", invalidArg("unknown table %q; see list_tables", buildModelName(schema, entity))), nil
+	}
+	info := buildModelInfo(schema, entity, model)
+
+	modelType := reflect.TypeOf(model)
+	for modelType != nil && (modelType.Kind() == reflect.Pointer || modelType.Kind() == reflect.Slice) {
+		modelType = modelType.Elem()
+	}
+	writable := map[string]bool{}
+	if modelType != nil && modelType.Kind() == reflect.Struct {
+		for jsonKey := range reflection.BuildJSONToDBColumnMap(modelType) {
+			writable[jsonKey] = true
+		}
+	}
+
+	type column struct {
+		Name       string `json:"name"`
+		Type       string `json:"type,omitempty"`
+		Nullable   bool   `json:"nullable"`
+		PrimaryKey bool   `json:"primary_key,omitempty"`
+		Unique     bool   `json:"unique,omitempty"`
+		Writable   bool   `json:"writable"`
+	}
+	cols := make([]column, 0, len(info.columns))
+	var writableNames []string
+	for _, c := range info.columns {
+		typ := c.sqlType
+		if typ == "" {
+			typ = c.goType
+		}
+		w := writable[c.jsonName]
+		cols = append(cols, column{Name: c.jsonName, Type: typ, Nullable: c.nullable, PrimaryKey: c.isPrimary, Unique: c.isUnique, Writable: w})
+		if w && !c.isPrimary {
+			writableNames = append(writableNames, c.jsonName)
+		}
+	}
+	return marshalResult(map[string]any{
+		"success":          true,
+		"table":            info.fullName,
+		"primary_key":      info.pkName,
+		"columns":          cols,
+		"relations":        info.relationNames,
+		"writable_columns": writableNames,
+		"operations":       opsFor(rules),
+		"filter_operators": filterOperators,
+		"limits": map[string]any{
+			"default_limit":     h.config.DefaultLimit,
+			"max_limit":         h.config.MaxLimit,
+			"max_offset":        h.config.MaxOffset,
+			"max_batch":         h.config.MaxBatch,
+			"max_preload_depth": h.config.MaxPreloadDepth,
+			"max_write_rows":    h.config.MaxWriteRows,
+		},
+	})
+}
+
+// --------------------------------------------------------------------------
+// Row tools
+// --------------------------------------------------------------------------
+
+// argID reads the id argument, which clients send as a string or a number.
+func argID(args map[string]any) string {
+	switch v := args["id"].(type) {
+	case string:
+		return v
+	case float64:
+		if v == float64(int64(v)) {
+			return fmt.Sprintf("%d", int64(v))
+		}
+		return fmt.Sprint(v)
+	}
+	return ""
+}
+
+// parseFiltersStrict is parseFilters for writes: a malformed filter is an error, never dropped.
+func parseFiltersStrict(raw any) ([]common.FilterOption, error) {
+	if raw == nil {
+		return nil, nil
+	}
+	items, ok := raw.([]any)
+	if !ok {
+		return nil, invalidArg("filters must be an array")
+	}
+	parsed := parseFilters(raw)
+	if len(parsed) != len(items) {
+		return nil, invalidArg("every filter needs a column and an operator")
+	}
+	return parsed, nil
+}
+
+func (h *Handler) handleSelect(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	args := req.GetArguments()
+	schema, entity, err := h.resolveTable(args, opSelect)
+	if err != nil {
+		return toolError("select_table", err), nil
+	}
+	count, _ := args["include_count"].(bool)
+	data, meta, err := h.executeReadCounted(ctx, schema, entity, argID(args), parseRequestOptions(args), count)
+	if err != nil {
+		return toolError("select_table", err), nil
+	}
+	if !count && meta != nil {
+		meta.Total, meta.Filtered = 0, 0
+	}
+	return marshalResult(map[string]any{"success": true, "data": data, "metadata": meta})
+}
+
+func (h *Handler) handleInsert(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	args := req.GetArguments()
+	schema, entity, err := h.resolveTable(args, opInsert)
+	if err != nil {
+		return toolError("insert_into_table", err), nil
+	}
+	data, ok := args["data"]
+	if !ok {
+		return toolError("insert_into_table", invalidArg("missing required argument: data")), nil
+	}
+	result, err := h.executeCreate(ctx, schema, entity, data)
+	if err != nil {
+		return toolError("insert_into_table", err), nil
+	}
+	return marshalResult(map[string]any{"success": true, "data": result})
+}
+
+// writeTarget parses id/filters/dry_run/confirm_token shared by update and delete.
+func writeTarget(args map[string]any) (id string, filters []common.FilterOption, dryRun bool, token string, err error) {
+	id = argID(args)
+	if filters, err = parseFiltersStrict(args["filters"]); err != nil {
+		return
+	}
+	if id != "" && len(filters) > 0 {
+		err = invalidArg("use either id or filters, not both")
+		return
+	}
+	if id == "" && len(filters) == 0 {
+		err = invalidArg("provide an id or at least one filter")
+		return
+	}
+	dryRun, _ = args["dry_run"].(bool)
+	token, _ = args["confirm_token"].(string)
+	return
+}
+
+func (h *Handler) handleUpdate(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	args := req.GetArguments()
+	schema, entity, err := h.resolveTable(args, opUpdate)
+	if err != nil {
+		return toolError("update_table", err), nil
+	}
+	data, ok := args["data"].(map[string]any)
+	if !ok {
+		return toolError("update_table", invalidArg("data must be an object")), nil
+	}
+	id, filters, dryRun, token, err := writeTarget(args)
+	if err != nil {
+		return toolError("update_table", err), nil
+	}
+	if id != "" && !dryRun {
+		result, err := h.executeUpdate(ctx, schema, entity, id, data)
+		if err != nil {
+			return toolError("update_table", err), nil
+		}
+		return marshalResult(map[string]any{"success": true, "data": result})
+	}
+	return h.runWhere(ctx, "update_table", whereRequest{schema: schema, entity: entity, op: "update", filters: h.idFilters(schema, entity, id, filters), data: data, dryRun: dryRun, confirmToken: token})
+}
+
+func (h *Handler) handleDelete(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	args := req.GetArguments()
+	schema, entity, err := h.resolveTable(args, opDelete)
+	if err != nil {
+		return toolError("delete_from_table", err), nil
+	}
+	id, filters, dryRun, token, err := writeTarget(args)
+	if err != nil {
+		return toolError("delete_from_table", err), nil
+	}
+	if id != "" && !dryRun {
+		result, err := h.executeDelete(ctx, schema, entity, id)
+		if err != nil {
+			return toolError("delete_from_table", err), nil
+		}
+		return marshalResult(map[string]any{"success": true, "data": result})
+	}
+	return h.runWhere(ctx, "delete_from_table", whereRequest{schema: schema, entity: entity, op: "delete", filters: h.idFilters(schema, entity, id, filters), dryRun: dryRun, confirmToken: token})
+}
+
+// idFilters turns an id into a primary-key filter so a dry run of an id write goes through the
+// same matching as a filter write.
+func (h *Handler) idFilters(schema, entity, id string, filters []common.FilterOption) []common.FilterOption {
+	if id == "" {
+		return filters
+	}
+	model, err := h.registry.GetModelByEntity(schema, entity)
+	if err != nil {
+		return filters
+	}
+	return []common.FilterOption{{Column: reflection.GetPrimaryKeyName(model), Operator: "eq", Value: id, LogicOperator: "AND"}}
+}
+
+func (h *Handler) runWhere(ctx context.Context, op string, req whereRequest) (*mcp.CallToolResult, error) {
+	res, err := h.executeWhere(ctx, req)
+	if err != nil {
+		return toolError(op, err), nil
+	}
+	return marshalResult(map[string]any{"success": true, "result": res})
+}
+
+// --------------------------------------------------------------------------
+// Functions
+// --------------------------------------------------------------------------
+
+func (h *Handler) handleListFunctions(ctx context.Context, _ mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	type param struct {
+		Name        string `json:"name"`
+		Type        string `json:"type"`
+		Required    bool   `json:"required"`
+		Description string `json:"description,omitempty"`
+	}
+	type fn struct {
+		Name        string  `json:"name"`
+		Description string  `json:"description,omitempty"`
+		Parameters  []param `json:"parameters"`
+	}
+	out := []fn{}
+	for _, f := range h.visibleFunctions(ctx) {
+		item := fn{Name: f.Name, Description: f.Description, Parameters: []param{}}
+		for _, p := range f.Params {
+			item.Parameters = append(item.Parameters, param{p.Name, p.Type, p.Required, p.Description})
+		}
+		out = append(out, item)
+	}
+	return marshalResult(map[string]any{"success": true, "functions": out})
+}
+
+func (h *Handler) handleCallFunction(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+	args := req.GetArguments()
+	name, _ := args["name"].(string)
+	if name == "" {
+		return toolError("call_function", invalidArg("missing required argument: name")), nil
+	}
+	fnArgs := map[string]any{}
+	if raw, ok := args["arguments"]; ok && raw != nil {
+		m, ok := raw.(map[string]any)
+		if !ok {
+			return toolError("call_function", invalidArg("arguments must be an object")), nil
+		}
+		fnArgs = m
+	}
+	result, err := h.executeCall(ctx, name, fnArgs)
+	if err != nil {
+		return toolError("call_function", err), nil
+	}
+	return marshalResult(map[string]any{"success": true, "result": result})
+}

pkg/resolvemcp/meta_test.go

@@ -0,0 +1,451 @@
+package resolvemcp
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"sort"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/mark3labs/mcp-go/mcp"
+
+	"github.com/bitechdev/ResolveSpec/pkg/common"
+	"github.com/bitechdev/ResolveSpec/pkg/modelregistry"
+	"github.com/bitechdev/ResolveSpec/pkg/security"
+)
+
+func callReq(args map[string]any) mcp.CallToolRequest {
+	var r mcp.CallToolRequest
+	r.Params.Arguments = args
+	return r
+}
+
+// payload decodes a tool result's text.
+func payload(t *testing.T, res *mcp.CallToolResult) map[string]any {
+	t.Helper()
+	if len(res.Content) == 0 {
+		t.Fatal("empty result")
+	}
+	tc, ok := res.Content[0].(mcp.TextContent)
+	if !ok {
+		t.Fatalf("content is %T", res.Content[0])
+	}
+	var m map[string]any
+	if err := json.Unmarshal([]byte(tc.Text), &m); err != nil {
+		t.Fatalf("not JSON: %q", tc.Text)
+	}
+	return m
+}
+
+func errCode(t *testing.T, res *mcp.CallToolResult) string {
+	t.Helper()
+	if !res.IsError {
+		t.Fatalf("expected an error result, got %v", payload(t, res))
+	}
+	e, _ := payload(t, res)["error"].(map[string]any)
+	code, _ := e["code"].(string)
+	return code
+}
+
+func TestMetaToolSetIsFixed(t *testing.T) {
+	h, _, _ := newTxHarness(t)
+	for _, name := range []string{"x1", "x2", "x3"} {
+		if err := h.RegisterModel("public", name, &txItem{}); err != nil {
+			t.Fatal(err)
+		}
+	}
+	var got []string
+	for name := range h.mcpServer.ListTools() {
+		got = append(got, name)
+	}
+	sort.Strings(got)
+	want := "call_function delete_from_table describe_table insert_into_table list_functions list_tables select_table update_table"
+	if strings.Join(got, " ") != want {
+		t.Fatalf("tools = %v\nwant   %s", got, want)
+	}
+}
+
+func TestListTablesShowsOnlyAllowedOperations(t *testing.T) {
+	h, _, ctx := newTxHarness(t)
+	_ = h.RegisterModelWithRules("public", "ro", &txItem{}, modelregistry.ModelRules{CanRead: true})
+	_ = h.RegisterModelWithRules("public", "hidden", &txItem{}, modelregistry.ModelRules{})
+	res, _ := h.handleListTables(ctx, callReq(nil))
+	tables, _ := payload(t, res)["tables"].([]any)
+	seen := map[string][]any{}
+	for _, tb := range tables {
+		m := tb.(map[string]any)
+		seen[m["table"].(string)] = m["operations"].([]any)
+	}
+	if _, ok := seen["public.hidden"]; ok {
+		t.Error("a table with no allowed operation must not be listed")
+	}
+	if ops := seen["public.ro"]; len(ops) != 1 || ops[0] != "select" {
+		t.Errorf("ro ops = %v", ops)
+	}
+	if ops := seen["public.items"]; len(ops) != 4 {
+		t.Errorf("default rules allow all four, got %v", ops)
+	}
+	// describe_table on a table with no allowed operation reads as unknown.
+	res, _ = h.handleDescribeTable(ctx, callReq(map[string]any{"table": "public.hidden"}))
+	if errCode(t, res) != CodeInvalidArgument {
+		t.Error("describe of a hidden table must look like an unknown table")
+	}
+}
+
+func TestDescribeTable(t *testing.T) {
+	h, _, ctx := newTxHarness(t)
+	if err := h.RegisterModel("public", "witems", &wItem{}); err != nil {
+		t.Fatal(err)
+	}
+	res, _ := h.handleDescribeTable(ctx, callReq(map[string]any{"table": "public.witems"}))
+	p := payload(t, res)
+	if p["primary_key"] != "id" {
+		t.Errorf("pk = %v", p["primary_key"])
+	}
+	w, _ := p["writable_columns"].([]any)
+	got := map[string]bool{}
+	for _, c := range w {
+		got[c.(string)] = true
+	}
+	if !got["name"] || !got["fullName"] || got["id"] || got["owner"] {
+		t.Errorf("writable columns = %v", w)
+	}
+	if lim, _ := p["limits"].(map[string]any); lim["max_limit"] != float64(1000) {
+		t.Errorf("limits = %v", p["limits"])
+	}
+}
+
+func TestSelectRespectsOperationRule(t *testing.T) {
+	h, _, ctx := newTxHarness(t)
+	_ = h.RegisterModelWithRules("public", "nowrite", &txItem{}, modelregistry.ModelRules{CanRead: true})
+	for tool, fn := range map[string]func(context.Context, mcp.CallToolRequest) (*mcp.CallToolResult, error){
+		"insert": h.handleInsert, "update": h.handleUpdate, "delete": h.handleDelete,
+	} {
+		res, _ := fn(ctx, callReq(map[string]any{"table": "public.nowrite", "data": map[string]any{"name": "a"}, "id": "1"}))
+		if errCode(t, res) != CodeForbidden {
+			t.Errorf("%s on a read-only table must be forbidden", tool)
+		}
+	}
+	res, _ := h.handleSelect(ctx, callReq(map[string]any{"table": "public.missing"}))
+	if errCode(t, res) != CodeInvalidArgument {
+		t.Error("unknown table must be invalid_argument")
+	}
+}
+
+func TestSelectCountOnlyWhenRequested(t *testing.T) {
+	h, mock, ctx := newTxHarness(t)
+	mock.ExpectBegin()
+	mock.ExpectQuery(`SELECT`).WillReturnRows(sqlmock.NewRows([]string{"id", "name"}).AddRow(1, "a"))
+	mock.ExpectCommit()
+	res, _ := h.handleSelect(ctx, callReq(map[string]any{"table": "public.items"}))
+	if res.IsError {
+		t.Fatal(payload(t, res))
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatal(err)
+	}
+	mock.ExpectBegin()
+	mock.ExpectQuery(`SELECT COUNT`).WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(41))
+	mock.ExpectQuery(`SELECT`).WillReturnRows(sqlmock.NewRows([]string{"id", "name"}).AddRow(1, "a"))
+	mock.ExpectCommit()
+	res, _ = h.handleSelect(ctx, callReq(map[string]any{"table": "public.items", "include_count": true}))
+	meta, _ := payload(t, res)["metadata"].(map[string]any)
+	if res.IsError || meta["total"] != float64(41) {
+		t.Fatalf("metadata = %v", meta)
+	}
+}
+
+// --- filter writes ---
+
+func matchRowsQuery(mock sqlmock.Sqlmock, ids ...int) {
+	rows := sqlmock.NewRows([]string{"id"})
+	for _, id := range ids {
+		rows.AddRow(id)
+	}
+	mock.ExpectQuery(`SELECT`).WillReturnRows(rows)
+}
+
+func updReq(filters any, extra map[string]any) mcp.CallToolRequest {
+	a := map[string]any{"table": "public.items", "data": map[string]any{"name": "z"}, "filters": filters}
+	for k, v := range extra {
+		a[k] = v
+	}
+	return callReq(a)
+}
+
+var statusFilter = []any{map[string]any{"column": "name", "operator": "=", "value": "a"}}
+
+func TestFilterUpdateNeedsPreviewThenToken(t *testing.T) {
+	h, mock, ctx := newTxHarness(t)
+
+	// 1. preview: counts, lists ids, issues a token, writes nothing.
+	mock.ExpectBegin()
+	matchRowsQuery(mock, 1, 2)
+	mock.ExpectCommit()
+	res, _ := h.handleUpdate(ctx, updReq(statusFilter, nil))
+	r, _ := payload(t, res)["result"].(map[string]any)
+	tok, _ := r["confirm_token"].(string)
+	if res.IsError || tok == "" || r["requires_confirmation"] != true || r["matched"] != float64(2) {
+		t.Fatalf("preview = %v", payload(t, res))
+	}
+
+	// 2. with the token: re-matches inside the tx, then writes.
+	mock.ExpectBegin()
+	matchRowsQuery(mock, 1, 2)
+	mock.ExpectExec(`UPDATE .* WHERE "id" IN \(\$2, \$3\)`).WillReturnResult(sqlmock.NewResult(0, 2))
+	mock.ExpectCommit()
+	res, _ = h.handleUpdate(ctx, updReq(statusFilter, map[string]any{"confirm_token": tok}))
+	r, _ = payload(t, res)["result"].(map[string]any)
+	if res.IsError || r["affected"] != float64(2) {
+		t.Fatalf("confirmed = %v", payload(t, res))
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatal(err)
+	}
+
+	// 3. a token is single use.
+	mock.ExpectBegin()
+	matchRowsQuery(mock, 1, 2)
+	mock.ExpectRollback()
+	res, _ = h.handleUpdate(ctx, updReq(statusFilter, map[string]any{"confirm_token": tok}))
+	if errCode(t, res) != CodeInvalidArgument {
+		t.Error("a spent token must be rejected")
+	}
+}
+
+func TestConfirmTokenBinding(t *testing.T) {
+	issue := func(t *testing.T) (*Handler, sqlmock.Sqlmock, context.Context, string) {
+		h, mock, ctx := newTxHarness(t)
+		mock.ExpectBegin()
+		matchRowsQuery(mock, 1)
+		mock.ExpectCommit()
+		res, _ := h.handleUpdate(ctx, updReq(statusFilter, nil))
+		r, _ := payload(t, res)["result"].(map[string]any)
+		return h, mock, ctx, r["confirm_token"].(string)
+	}
+	reject := func(t *testing.T, h *Handler, mock sqlmock.Sqlmock, ctx context.Context, req mcp.CallToolRequest, rows ...int) {
+		t.Helper()
+		mock.ExpectBegin()
+		matchRowsQuery(mock, rows...)
+		mock.ExpectRollback()
+		res, _ := h.handleUpdate(ctx, req)
+		if errCode(t, res) != CodeInvalidArgument {
+			t.Fatal("token must be rejected")
+		}
+	}
+	t.Run("changed data", func(t *testing.T) {
+		h, mock, ctx, tok := issue(t)
+		req := updReq(statusFilter, map[string]any{"confirm_token": tok, "data": map[string]any{"name": "different"}})
+		reject(t, h, mock, ctx, req, 1)
+	})
+	t.Run("changed filters", func(t *testing.T) {
+		h, mock, ctx, tok := issue(t)
+		other := []any{map[string]any{"column": "name", "operator": "=", "value": "b"}}
+		reject(t, h, mock, ctx, updReq(other, map[string]any{"confirm_token": tok}), 1)
+	})
+	t.Run("rows changed since preview", func(t *testing.T) {
+		h, mock, ctx, tok := issue(t)
+		reject(t, h, mock, ctx, updReq(statusFilter, map[string]any{"confirm_token": tok}), 1, 2)
+	})
+	t.Run("other user", func(t *testing.T) {
+		h, mock, ctx, tok := issue(t)
+		other := context.WithValue(ctx, security.UserContextKey, &security.UserContext{UserID: 99, UserName: "mallory"})
+		reject(t, h, mock, other, updReq(statusFilter, map[string]any{"confirm_token": tok}), 1)
+	})
+	t.Run("other table", func(t *testing.T) {
+		h, mock, ctx, tok := issue(t)
+		if err := h.RegisterModel("public", "other", &txItem{}); err != nil {
+			t.Fatal(err)
+		}
+		req := updReq(statusFilter, map[string]any{"confirm_token": tok, "table": "public.other"})
+		reject(t, h, mock, ctx, req, 1)
+	})
+	t.Run("expired", func(t *testing.T) {
+		h, mock, ctx, tok := issue(t)
+		h.confirms.now = func() time.Time { return time.Now().Add(time.Hour) }
+		reject(t, h, mock, ctx, updReq(statusFilter, map[string]any{"confirm_token": tok}), 1)
+	})
+}
+
+func TestFilterWriteGuardrails(t *testing.T) {
+	h, mock, ctx := newTxHarness(t)
+	for name, req := range map[string]mcp.CallToolRequest{
+		"neither id nor filters": callReq(map[string]any{"table": "public.items", "data": map[string]any{"name": "z"}}),
+		"both id and filters":    updReq(statusFilter, map[string]any{"id": "1"}),
+		"malformed filter":       updReq([]any{map[string]any{"column": "name"}}, nil),
+		"unknown column":         updReq([]any{map[string]any{"column": "secret", "operator": "=", "value": 1}}, nil),
+		"injection in column":    updReq([]any{map[string]any{"column": "name) OR (1=1", "operator": "=", "value": 1}}, nil),
+		"unknown operator":       updReq([]any{map[string]any{"column": "name", "operator": "ɸ", "value": 1}}, nil),
+		"missing value":          updReq([]any{map[string]any{"column": "name", "operator": "="}}, nil),
+		"unknown data field":     callReq(map[string]any{"table": "public.items", "data": map[string]any{"role": "x"}, "filters": statusFilter}),
+	} {
+		res, _ := h.handleUpdate(ctx, req)
+		if errCode(t, res) != CodeInvalidArgument {
+			t.Errorf("%s: want invalid_argument", name)
+		}
+	}
+	// Rejected before any SQL ran.
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestFilterWriteRowCap(t *testing.T) {
+	h, mock, ctx := newTxHarness(t)
+	h.config.MaxWriteRows = 2
+	mock.ExpectBegin()
+	matchRowsQuery(mock, 1, 2, 3)
+	mock.ExpectRollback()
+	res, _ := h.handleDelete(ctx, callReq(map[string]any{"table": "public.items", "filters": statusFilter}))
+	if errCode(t, res) != CodeLimitExceeded {
+		t.Fatal("want limit_exceeded")
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestDryRunWritesNothing(t *testing.T) {
+	h, mock, ctx := newTxHarness(t)
+	mock.ExpectBegin()
+	matchRowsQuery(mock, 5)
+	mock.ExpectCommit()
+	res, _ := h.handleDelete(ctx, callReq(map[string]any{"table": "public.items", "filters": statusFilter, "dry_run": true}))
+	r, _ := payload(t, res)["result"].(map[string]any)
+	if res.IsError || r["dry_run"] != true || r["matched"] != float64(1) || r["confirm_token"] != nil {
+		t.Fatalf("dry run = %v", payload(t, res))
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestIDWriteNeedsNoToken(t *testing.T) {
+	h, mock, ctx := newTxHarness(t)
+	mock.ExpectBegin()
+	mock.ExpectQuery(`SELECT`).WillReturnRows(sqlmock.NewRows([]string{"id", "name"}).AddRow(7, "a"))
+	mock.ExpectExec(`DELETE`).WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectCommit()
+	res, _ := h.handleDelete(ctx, callReq(map[string]any{"table": "public.items", "id": float64(7)}))
+	if res.IsError {
+		t.Fatal(payload(t, res))
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+// --- functions ---
+
+func TestRegisterFunctionValidation(t *testing.T) {
+	h, _, _ := newTxHarness(t)
+	noop := func(context.Context, common.Database, map[string]any) (any, error) { return nil, nil }
+	bad := map[string]Function{
+		"bad name":        {Name: "1x", Handler: noop},
+		"neither":         {Name: "f"},
+		"both":            {Name: "f", Handler: noop, Procedure: "p"},
+		"bad procedure":   {Name: "f", Procedure: "p(); drop table x"},
+		"bad param type":  {Name: "f", Handler: noop, Params: []FunctionParam{{Name: "a", Type: "blob"}}},
+		"duplicate param": {Name: "f", Handler: noop, Params: []FunctionParam{{Name: "a", Type: "string"}, {Name: "a", Type: "string"}}},
+		"bad param name":  {Name: "f", Handler: noop, Params: []FunctionParam{{Name: "a b", Type: "string"}}},
+	}
+	for name, f := range bad {
+		if err := h.RegisterFunction(f); err == nil {
+			t.Errorf("%s: expected error", name)
+		}
+	}
+	if err := h.RegisterFunction(Function{Name: "ok", Handler: noop}); err != nil {
+		t.Fatal(err)
+	}
+	if err := h.RegisterFunction(Function{Name: "ok", Handler: noop}); err == nil {
+		t.Error("duplicate name must fail")
+	}
+}
+
+func TestCallFunctionValidatesAndRunsInTx(t *testing.T) {
+	h, mock, ctx := newTxHarness(t)
+	var gotArgs map[string]any
+	var gotTx common.Database
+	if err := h.RegisterFunction(Function{
+		Name: "greet", Description: "says hi",
+		Params: []FunctionParam{{Name: "who", Type: ParamString, Required: true}, {Name: "n", Type: ParamInteger}},
+		Handler: func(_ context.Context, tx common.Database, args map[string]any) (any, error) {
+			gotArgs, gotTx = args, tx
+			return map[string]any{"hello": args["who"]}, nil
+		},
+	}); err != nil {
+		t.Fatal(err)
+	}
+	tr := traceHooks(h, OnTxBegin, BeforeCall, AfterCall)
+
+	for name, args := range map[string]map[string]any{
+		"missing required": {},
+		"wrong type":       {"who": 5},
+		"fractional int":   {"who": "x", "n": 1.5},
+		"unknown arg":      {"who": "x", "extra": 1},
+	} {
+		res, _ := h.handleCallFunction(ctx, callReq(map[string]any{"name": "greet", "arguments": args}))
+		if errCode(t, res) != CodeInvalidArgument {
+			t.Errorf("%s: want invalid_argument", name)
+		}
+	}
+	res, _ := h.handleCallFunction(ctx, callReq(map[string]any{"name": "nope"}))
+	if errCode(t, res) != CodeInvalidArgument {
+		t.Error("unknown function must be invalid_argument")
+	}
+
+	mock.ExpectBegin()
+	mock.ExpectCommit()
+	res, _ = h.handleCallFunction(ctx, callReq(map[string]any{"name": "greet", "arguments": map[string]any{"who": "kim", "n": float64(2)}}))
+	if res.IsError || gotArgs["who"] != "kim" || gotTx == nil {
+		t.Fatalf("call = %v", payload(t, res))
+	}
+	tr.assertOrder(t, "on_tx_begin", "before_call", "after_call")
+	if tr.txs["before_call"][0] != tr.txs["on_tx_begin"][0] {
+		t.Error("the call must run in the OnTxBegin transaction")
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestFunctionAuthorizeHidesAndBlocks(t *testing.T) {
+	h, _, ctx := newTxHarness(t)
+	noop := func(context.Context, common.Database, map[string]any) (any, error) { return "ran", nil }
+	_ = h.RegisterFunction(Function{Name: "open", Handler: noop})
+	_ = h.RegisterFunction(Function{Name: "admin_only", Handler: noop, Authorize: func(context.Context) error { return errors.New("no") }})
+
+	res, _ := h.handleListFunctions(ctx, callReq(nil))
+	fns, _ := payload(t, res)["functions"].([]any)
+	if len(fns) != 1 || fns[0].(map[string]any)["name"] != "open" {
+		t.Fatalf("visible functions = %v", fns)
+	}
+	res, _ = h.handleCallFunction(ctx, callReq(map[string]any{"name": "admin_only"}))
+	if errCode(t, res) != CodeInvalidArgument {
+		t.Error("an unauthorized function must look unknown")
+	}
+}
+
+func TestProcedureFunctionCallShape(t *testing.T) {
+	h, mock, ctx := newTxHarness(t)
+	if err := h.RegisterFunction(Function{
+		Name: "recalc", Procedure: "app.recalc_totals",
+		Params: []FunctionParam{{Name: "account", Type: ParamInteger, Required: true}, {Name: "opts", Type: ParamObject}},
+	}); err != nil {
+		t.Fatal(err)
+	}
+	mock.ExpectBegin()
+	mock.ExpectQuery(`SELECT \* FROM app\.recalc_totals\(\$1, \$2::jsonb\)`).WithArgs(float64(3), nil).
+		WillReturnRows(sqlmock.NewRows([]string{"total"}).AddRow(10))
+	mock.ExpectCommit()
+	res, _ := h.handleCallFunction(ctx, callReq(map[string]any{"name": "recalc", "arguments": map[string]any{"account": float64(3)}}))
+	if res.IsError {
+		t.Fatal(payload(t, res))
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatal(err)
+	}
+}

pkg/resolvemcp/tools.go

@@ -1,7 +1,6 @@
 package resolvemcp
 
 import (
-	"context"
 	"encoding/json"
 	"fmt"
 	"reflect"
@@ -10,34 +9,9 @@ import (
 	"github.com/mark3labs/mcp-go/mcp"
 
 	"github.com/bitechdev/ResolveSpec/pkg/common"
-	"github.com/bitechdev/ResolveSpec/pkg/logger"
 	"github.com/bitechdev/ResolveSpec/pkg/reflection"
 )
 
-// toolName builds the MCP tool name for a given operation and model.
-func toolName(operation, schema, entity string) string {
-	if schema == "" {
-		return fmt.Sprintf("%s_%s", operation, entity)
-	}
-	return fmt.Sprintf("%s_%s_%s", operation, schema, entity)
-}
-
-// registerModelTools registers the four CRUD tools and resource for a model.
-func registerModelTools(h *Handler, schema, entity string, model interface{}) {
-	info := buildModelInfo(schema, entity, model)
-	registerReadTool(h, schema, entity, info)
-	registerCreateTool(h, schema, entity, info)
-	registerUpdateTool(h, schema, entity, info)
-	registerDeleteTool(h, schema, entity, info)
-	registerModelResource(h, schema, entity, info)
-
-	logger.Info("[resolvemcp] Registered MCP tools for %s", info.fullName)
-}
-
-// --------------------------------------------------------------------------
-// Model introspection
-// --------------------------------------------------------------------------
-
 // modelInfo holds pre-computed metadata for a model used in tool descriptions.
 type modelInfo struct {
 	fullName      string // e.g. "public.users"
@@ -247,330 +221,8 @@ func writableColumnNames(cols []columnInfo) []string {
 	return names
 }
 
-// --------------------------------------------------------------------------
-// Read tool
-// --------------------------------------------------------------------------
-
-func registerReadTool(h *Handler, schema, entity string, info modelInfo) {
-	name := toolName("read", schema, entity)
-
-	var descParts []string
-	descParts = append(descParts, fmt.Sprintf("Read records from the '%s' database table.", info.fullName))
-	if info.pkName != "" {
-		descParts = append(descParts, fmt.Sprintf("Primary key: '%s'. Pass it via 'id' to fetch a single record.", info.pkName))
-	}
-	if info.schemaDoc != "" {
-		descParts = append(descParts, info.schemaDoc)
-	}
-	descParts = append(descParts,
-		"Pagination: use 'limit'/'offset' for offset-based paging, or 'cursor_forward'/'cursor_backward' (pass the primary key value of the last/first record on the current page) for cursor-based paging.",
-		"Filtering: each filter object requires 'column' (JSON field name) and 'operator'. Supported operators: = != > < >= <= like ilike in is_null is_not_null. Combine with 'logic_operator': AND (default) or OR.",
-		"Sorting: each sort object requires 'column' and 'direction' (asc or desc).",
-	)
-	if len(info.relationNames) > 0 {
-		descParts = append(descParts, fmt.Sprintf("Preloadable relations: %s. Pass relation name in 'preloads'.", strings.Join(info.relationNames, ", ")))
-	}
-
-	description := strings.Join(descParts, "\n\n")
-
-	filterDesc := `Array of filter objects. Example: [{"column":"status","operator":"=","value":"active"},{"column":"age","operator":">","value":18,"logic_operator":"AND"}]`
-	if len(info.columns) > 0 {
-		filterDesc += fmt.Sprintf(" Available columns: %s.", columnNameList(info.columns))
-	}
-
-	sortDesc := `Array of sort objects. Example: [{"column":"created_at","direction":"desc"}]`
-	if len(info.columns) > 0 {
-		sortDesc += fmt.Sprintf(" Available columns: %s.", columnNameList(info.columns))
-	}
-
-	tool := mcp.NewTool(name,
-		mcp.WithDescription(description),
-		mcp.WithString("id",
-			mcp.Description(fmt.Sprintf("Primary key (%s) of a single record to fetch. Omit to return multiple records.", info.pkName)),
-		),
-		mcp.WithNumber("limit",
-			mcp.Description("Maximum number of records to return per page. Recommended: 10–100."),
-		),
-		mcp.WithNumber("offset",
-			mcp.Description("Number of records to skip (for offset-based pagination). Use with 'limit'."),
-		),
-		mcp.WithString("cursor_forward",
-			mcp.Description(fmt.Sprintf("Cursor for the next page: pass the '%s' value of the last record on the current page. Requires 'sort' to be set.", info.pkName)),
-		),
-		mcp.WithString("cursor_backward",
-			mcp.Description(fmt.Sprintf("Cursor for the previous page: pass the '%s' value of the first record on the current page. Requires 'sort' to be set.", info.pkName)),
-		),
-		mcp.WithArray("columns",
-			mcp.Description(fmt.Sprintf("Columns to include in the result. Omit to return all columns. Available: %s.", columnNameList(info.columns))),
-		),
-		mcp.WithArray("omit_columns",
-			mcp.Description(fmt.Sprintf("Columns to exclude from the result. Available: %s.", columnNameList(info.columns))),
-		),
-		mcp.WithArray("filters",
-			mcp.Description(filterDesc),
-		),
-		mcp.WithArray("sort",
-			mcp.Description(sortDesc),
-		),
-		mcp.WithArray("preloads",
-			mcp.Description(buildPreloadDesc(info)),
-		),
-	)
-
-	h.mcpServer.AddTool(tool, func(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
-		args := req.GetArguments()
-		id, _ := args["id"].(string)
-		options := parseRequestOptions(args)
-
-		data, metadata, err := h.executeRead(ctx, schema, entity, id, options)
-		if err != nil {
-			return toolError("tool", err), nil
-		}
-
-		return marshalResult(map[string]interface{}{
-			"success":  true,
-			"data":     data,
-			"metadata": metadata,
-		})
-	})
-}
-
-func buildPreloadDesc(info modelInfo) string {
-	if len(info.relationNames) == 0 {
-		return `Array of relation preload objects. Each object: {"relation":"RelationName"}. No relations defined on this model.`
-	}
-	return fmt.Sprintf(
-		`Array of relation preload objects. Each object: {"relation":"RelationName","columns":["col1","col2"]}. Available relations: %s.`,
-		strings.Join(info.relationNames, ", "),
-	)
-}
-
-// --------------------------------------------------------------------------
-// Create tool
-// --------------------------------------------------------------------------
-
-func registerCreateTool(h *Handler, schema, entity string, info modelInfo) {
-	name := toolName("create", schema, entity)
-
-	writable := writableColumnNames(info.columns)
-
-	var descParts []string
-	descParts = append(descParts, fmt.Sprintf("Create one or more new records in the '%s' table.", info.fullName))
-	if len(writable) > 0 {
-		descParts = append(descParts, fmt.Sprintf("Writable fields: %s.", strings.Join(writable, ", ")))
-	}
-	if info.pkName != "" {
-		descParts = append(descParts, fmt.Sprintf("The primary key ('%s') is typically auto-generated — omit it unless you need to supply it explicitly.", info.pkName))
-	}
-	descParts = append(descParts,
-		"Pass a single JSON object to 'data' to create one record. Pass an array of objects to create multiple records in a single transaction (all succeed or all fail).",
-	)
-	if info.schemaDoc != "" {
-		descParts = append(descParts, info.schemaDoc)
-	}
-
-	description := strings.Join(descParts, "\n\n")
-
-	dataDesc := "Record fields to create."
-	if len(writable) > 0 {
-		dataDesc += fmt.Sprintf(" Writable fields: %s.", strings.Join(writable, ", "))
-	}
-	dataDesc += " Pass a single object or an array of objects."
-
-	tool := mcp.NewTool(name,
-		mcp.WithDescription(description),
-		mcp.WithObject("data",
-			mcp.Description(dataDesc),
-			mcp.Required(),
-		),
-	)
-
-	h.mcpServer.AddTool(tool, func(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
-		args := req.GetArguments()
-		data, ok := args["data"]
-		if !ok {
-			return mcp.NewToolResultError("missing required argument: data"), nil
-		}
-
-		result, err := h.executeCreate(ctx, schema, entity, data)
-		if err != nil {
-			return toolError("tool", err), nil
-		}
-
-		return marshalResult(map[string]interface{}{
-			"success": true,
-			"data":    result,
-		})
-	})
-}
-
-// --------------------------------------------------------------------------
-// Update tool
-// --------------------------------------------------------------------------
-
-func registerUpdateTool(h *Handler, schema, entity string, info modelInfo) {
-	name := toolName("update", schema, entity)
-
-	writable := writableColumnNames(info.columns)
-
-	var descParts []string
-	descParts = append(descParts, fmt.Sprintf("Update an existing record in the '%s' table.", info.fullName))
-	if info.pkName != "" {
-		descParts = append(descParts, fmt.Sprintf("Identify the record by its primary key ('%s') via the 'id' argument or by including '%s' inside 'data'.", info.pkName, info.pkName))
-	}
-	if len(writable) > 0 {
-		descParts = append(descParts, fmt.Sprintf("Updatable fields: %s.", strings.Join(writable, ", ")))
-	}
-	descParts = append(descParts,
-		"Only non-null, non-empty fields in 'data' are applied — existing values are preserved for fields you omit. Returns the merged record as stored.",
-	)
-	if info.schemaDoc != "" {
-		descParts = append(descParts, info.schemaDoc)
-	}
-
-	description := strings.Join(descParts, "\n\n")
-
-	idDesc := fmt.Sprintf("Primary key ('%s') of the record to update. Can also be included inside 'data'.", info.pkName)
-
-	dataDesc := "Fields to update (non-null, non-empty values are merged into the existing record)."
-	if len(writable) > 0 {
-		dataDesc += fmt.Sprintf(" Updatable fields: %s.", strings.Join(writable, ", "))
-	}
-
-	tool := mcp.NewTool(name,
-		mcp.WithDescription(description),
-		mcp.WithString("id",
-			mcp.Description(idDesc),
-		),
-		mcp.WithObject("data",
-			mcp.Description(dataDesc),
-			mcp.Required(),
-		),
-	)
-
-	h.mcpServer.AddTool(tool, func(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
-		args := req.GetArguments()
-		id, _ := args["id"].(string)
-
-		data, ok := args["data"]
-		if !ok {
-			return mcp.NewToolResultError("missing required argument: data"), nil
-		}
-		dataMap, ok := data.(map[string]interface{})
-		if !ok {
-			return mcp.NewToolResultError("data must be an object"), nil
-		}
-
-		result, err := h.executeUpdate(ctx, schema, entity, id, dataMap)
-		if err != nil {
-			return toolError("tool", err), nil
-		}
-
-		return marshalResult(map[string]interface{}{
-			"success": true,
-			"data":    result,
-		})
-	})
-}
-
-// --------------------------------------------------------------------------
-// Delete tool
-// --------------------------------------------------------------------------
-
-func registerDeleteTool(h *Handler, schema, entity string, info modelInfo) {
-	name := toolName("delete", schema, entity)
-
-	descParts := []string{
-		fmt.Sprintf("Delete a record from the '%s' table by its primary key.", info.fullName),
-	}
-	if info.pkName != "" {
-		descParts = append(descParts, fmt.Sprintf("Pass the '%s' value of the record to delete via the 'id' argument.", info.pkName))
-	}
-	descParts = append(descParts, "Returns the deleted record. This operation is irreversible.")
-
-	description := strings.Join(descParts, " ")
-
-	tool := mcp.NewTool(name,
-		mcp.WithDescription(description),
-		mcp.WithString("id",
-			mcp.Description(fmt.Sprintf("Primary key ('%s') of the record to delete.", info.pkName)),
-			mcp.Required(),
-		),
-	)
-
-	h.mcpServer.AddTool(tool, func(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
-		args := req.GetArguments()
-		id, _ := args["id"].(string)
-
-		result, err := h.executeDelete(ctx, schema, entity, id)
-		if err != nil {
-			return toolError("tool", err), nil
-		}
-
-		return marshalResult(map[string]interface{}{
-			"success": true,
-			"data":    result,
-		})
-	})
-}
-
-// --------------------------------------------------------------------------
-// Resource registration
-// --------------------------------------------------------------------------
-
-func registerModelResource(h *Handler, schema, entity string, info modelInfo) {
-	resourceURI := info.fullName
-
-	var resourceDesc strings.Builder
-	fmt.Fprintf(&resourceDesc, "Database table: %s", info.fullName)
-	if info.pkName != "" {
-		fmt.Fprintf(&resourceDesc, " (primary key: %s)", info.pkName)
-	}
-	if info.schemaDoc != "" {
-		resourceDesc.WriteString("\n\n")
-		resourceDesc.WriteString(info.schemaDoc)
-	}
-
-	resource := mcp.NewResource(
-		resourceURI,
-		entity,
-		mcp.WithResourceDescription(resourceDesc.String()),
-		mcp.WithMIMEType("application/json"),
-	)
-
-	h.mcpServer.AddResource(resource, func(ctx context.Context, req mcp.ReadResourceRequest) ([]mcp.ResourceContents, error) {
-		limit := 100
-		options := common.RequestOptions{Limit: &limit}
-
-		data, metadata, err := h.executeRead(ctx, schema, entity, "", options)
-		if err != nil {
-			return nil, err
-		}
-
-		payload := map[string]interface{}{
-			"data":     data,
-			"metadata": metadata,
-		}
-		jsonBytes, err := json.Marshal(payload)
-		if err != nil {
-			return nil, fmt.Errorf("error marshaling resource: %w", err)
-		}
-
-		return []mcp.ResourceContents{
-			mcp.TextResourceContents{
-				URI:      req.Params.URI,
-				MIMEType: "application/json",
-				Text:     string(jsonBytes),
-			},
-		}, nil
-	})
-}
-
-// --------------------------------------------------------------------------
-// Argument parsing helpers
-// --------------------------------------------------------------------------
-
-// parseRequestOptions converts raw MCP tool arguments into common.RequestOptions.
+// parseRequestOptions reads the paging, filter, sort, column and preload arguments shared
+// by the read tools.
 func parseRequestOptions(args map[string]interface{}) common.RequestOptions {
 	options := common.RequestOptions{}
 

pkg/resolvemcp/writewhere.go

@@ -0,0 +1,259 @@
+package resolvemcp
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"regexp"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/bitechdev/ResolveSpec/pkg/common"
+	"github.com/bitechdev/ResolveSpec/pkg/reflection"
+	"github.com/bitechdev/ResolveSpec/pkg/security"
+)
+
+// previewRows is how many matched primary keys a preview lists.
+const previewRows = 10
+
+var filterColumnRe = regexp.MustCompile(`^[A-Za-z_][A-Za-z0-9_]*$`)
+
+// writeOperators are the filter operators a filter write accepts.
+var writeOperators = map[string]bool{
+	"eq": true, "=": true, "neq": true, "!=": true, "<>": true, "gt": true, ">": true, "gte": true, ">=": true,
+	"lt": true, "<": true, "lte": true, "<=": true, "like": true, "ilike": true, "in": true,
+	"is_null": true, "is_not_null": true,
+}
+
+// validateWriteFilters requires at least one filter and that every filter is usable. Reads
+// silently drop filters they cannot apply; a write must not, because a dropped filter widens
+// the set of rows the write touches.
+func validateWriteFilters(model interface{}, filters []common.FilterOption) error {
+	if len(filters) == 0 {
+		return invalidArg("provide an id or at least one filter")
+	}
+	v := common.NewColumnValidator(model)
+	for _, f := range filters {
+		if !filterColumnRe.MatchString(f.Column) || !v.IsValidColumn(f.Column) {
+			return invalidArg("unknown filter column %q", truncate(f.Column))
+		}
+		if !writeOperators[strings.ToLower(f.Operator)] {
+			return invalidArg("unsupported filter operator %q", truncate(f.Operator))
+		}
+		op := strings.ToLower(f.Operator)
+		if op != "is_null" && op != "is_not_null" && f.Value == nil {
+			return invalidArg("filter on %q needs a value", f.Column)
+		}
+	}
+	return nil
+}
+
+// whereRequest describes a filter-based update or delete.
+type whereRequest struct {
+	schema, entity string
+	op             string // "update" or "delete"
+	filters        []common.FilterOption
+	data           map[string]interface{} // update only
+	dryRun         bool
+	confirmToken   string
+}
+
+// whereResult is what a filter write returns to the client.
+type whereResult struct {
+	DryRun          bool          `json:"dry_run,omitempty"`
+	RequiresConfirm bool          `json:"requires_confirmation,omitempty"`
+	Matched         int           `json:"matched"`
+	Preview         []interface{} `json:"preview,omitempty"`
+	ConfirmToken    string        `json:"confirm_token,omitempty"`
+	ExpiresInSec    int           `json:"expires_in_seconds,omitempty"`
+	Affected        int           `json:"affected,omitempty"`
+	IDs             []interface{} `json:"ids,omitempty"`
+}
+
+// executeWhere runs a filter-based write behind the guardrails: filters are validated, the
+// matching rows are counted inside the transaction (aborting above Config.MaxWriteRows), and
+// without dry_run the write only happens with a confirm token from a preview of the same
+// request that matched the same rows.
+func (h *Handler) executeWhere(ctx context.Context, req whereRequest) (_ *whereResult, retErr error) {
+	defer recoverPanic(&retErr)
+	ctx, cancel := h.callContext(ctx)
+	defer cancel()
+
+	model, err := h.registry.GetModelByEntity(req.schema, req.entity)
+	if err != nil {
+		return nil, invalidArg("model not found: %s", buildModelName(req.schema, req.entity))
+	}
+	unwrapped, err := common.ValidateAndUnwrapModel(model)
+	if err != nil {
+		return nil, errInternal
+	}
+	model = unwrapped.Model
+	if err := validateWriteFilters(model, req.filters); err != nil {
+		return nil, err
+	}
+	pkName := reflection.GetPrimaryKeyName(model)
+	if pkName == "" {
+		return nil, invalidArg("table has no primary key; filter writes are not available")
+	}
+	tableName := h.getTableName(req.schema, req.entity, model)
+	ctx = withRequestData(h.withModelRules(ctx, req.schema, req.entity), req.schema, req.entity, tableName, model, unwrapped.ModelPtr)
+
+	var setCols map[string]interface{}
+	if req.op == "update" {
+		if setCols, err = writeColumns(model, req.data); err != nil {
+			return nil, err
+		}
+		for col := range setCols {
+			if strings.EqualFold(col, pkName) {
+				delete(setCols, col)
+			}
+		}
+		if len(setCols) == 0 {
+			return nil, invalidArg("no updatable fields in data")
+		}
+	}
+
+	hookCtx := &HookContext{
+		Context: ctx, Handler: h, Schema: req.schema, Entity: req.entity, Model: model,
+		Operation: req.op, Tx: h.db,
+	}
+	if req.op == "update" {
+		hookCtx.Data = req.data
+	}
+	if err := h.hooks.Execute(BeforeHandle, hookCtx); err != nil {
+		return nil, err
+	}
+
+	user := callerKey(ctx)
+	table := buildModelName(req.schema, req.entity)
+	res := &whereResult{}
+	err = h.runInTx(ctx, hookCtx, func(tx common.Database) error {
+		before, after := BeforeUpdate, AfterUpdate
+		if req.op == "delete" {
+			before, after = BeforeDelete, AfterDelete
+		}
+		if err := h.hooks.Execute(before, hookCtx); err != nil {
+			return err
+		}
+		if req.op == "update" {
+			// A hook (column security) may have narrowed the payload.
+			if m, ok := hookCtx.Data.(map[string]interface{}); ok {
+				if setCols, err = writeColumns(model, m); err != nil {
+					return err
+				}
+				for col := range setCols {
+					if strings.EqualFold(col, pkName) {
+						delete(setCols, col)
+					}
+				}
+				if len(setCols) == 0 {
+					return invalidArg("no updatable fields in data")
+				}
+			}
+		}
+
+		ids, err := h.matchRows(ctx, tx, hookCtx, model, unwrapped.ModelType, tableName, pkName, req.filters)
+		if err != nil {
+			return err
+		}
+		res.Matched = len(ids)
+		for i := 0; i < len(ids) && i < previewRows; i++ {
+			res.Preview = append(res.Preview, ids[i])
+		}
+
+		if req.dryRun {
+			res.DryRun = true
+			return nil
+		}
+		binding, err := bindingHash(req.op, req.filters, req.data, ids)
+		if err != nil {
+			return err
+		}
+		if req.confirmToken == "" {
+			tok, err := h.confirms.issue(user, table, req.op, binding, h.config.ConfirmTTL)
+			if err != nil {
+				return err
+			}
+			res.RequiresConfirm = true
+			res.ConfirmToken = tok
+			res.ExpiresInSec = int(h.config.ConfirmTTL / time.Second)
+			return nil
+		}
+		if err := h.confirms.consume(req.confirmToken, user, table, req.op, binding); err != nil {
+			return err
+		}
+		if len(ids) == 0 {
+			return nil
+		}
+
+		inList := make([]string, len(ids))
+		for i := range ids {
+			inList[i] = "?"
+		}
+		cond := fmt.Sprintf("%s IN (%s)", common.QuoteIdent(pkName), strings.Join(inList, ", "))
+		var affected int64
+		if req.op == "update" {
+			r, err := tx.NewUpdate().Table(tableName).SetMap(setCols).Where(cond, ids...).Exec(ctx)
+			if err != nil {
+				return fmt.Errorf("error updating records: %w", err)
+			}
+			affected = r.RowsAffected()
+		} else {
+			r, err := tx.NewDelete().Table(tableName).Where(cond, ids...).Exec(ctx)
+			if err != nil {
+				return fmt.Errorf("delete error: %w", err)
+			}
+			affected = r.RowsAffected()
+		}
+		if int(affected) != len(ids) {
+			// Rows changed under us: roll back rather than report a partial write.
+			return invalidArg("matched rows changed during the write; repeat the preview")
+		}
+		res.Affected = int(affected)
+		res.IDs = ids
+		hookCtx.Result = map[string]interface{}{"ids": ids, "count": len(ids)}
+		return h.hooks.Execute(after, hookCtx)
+	})
+	if err != nil {
+		return nil, err
+	}
+	return res, nil
+}
+
+// matchRows returns the primary keys of the rows the filters select, narrowed by the BeforeScan
+// hooks (row security). It fails when more than Config.MaxWriteRows match.
+func (h *Handler) matchRows(ctx context.Context, tx common.Database, hookCtx *HookContext, model interface{}, modelType reflect.Type, tableName, pkName string, filters []common.FilterOption) ([]interface{}, error) {
+	sliceType := reflect.SliceOf(reflect.PointerTo(modelType))
+	dest := reflect.New(sliceType)
+	q := tx.NewSelect().Model(dest.Interface())
+	if provider, ok := reflect.New(modelType).Interface().(common.TableNameProvider); !ok || provider.TableName() == "" {
+		q = q.Table(tableName)
+	}
+	q = h.applyFilters(q.Column(pkName), filters, model)
+	hookCtx.Query = q
+	if err := h.hooks.Execute(BeforeScan, hookCtx); err != nil {
+		return nil, err
+	}
+	if err := hookCtx.Query.Limit(h.config.MaxWriteRows + 1).ScanModel(ctx); err != nil {
+		return nil, fmt.Errorf("error matching records: %w", err)
+	}
+	rows := dest.Elem()
+	if rows.Len() > h.config.MaxWriteRows {
+		return nil, NewClientError(CodeLimitExceeded, fmt.Sprintf("the filters match more than %d rows; narrow them", h.config.MaxWriteRows))
+	}
+	ids := make([]interface{}, 0, rows.Len())
+	for i := 0; i < rows.Len(); i++ {
+		ids = append(ids, reflection.GetPrimaryKeyValue(rows.Index(i).Interface()))
+	}
+	sort.Slice(ids, func(i, j int) bool { return fmt.Sprint(ids[i]) < fmt.Sprint(ids[j]) })
+	return ids, nil
+}
+
+// callerKey identifies the caller for confirm-token binding.
+func callerKey(ctx context.Context) string {
+	if uc, ok := security.GetUserContext(ctx); ok && uc != nil {
+		return fmt.Sprintf("%d/%s", uc.UserID, uc.UserName)
+	}
+	return "anonymous"
+}