Add usage commands, a vendor-neutral usage format and a knowledge base

internal/store/migrations/062-add-usage-commands.sql

@@ -0,0 +1,4 @@
+CREATE TABLE usage_commands (
+	vendor TEXT PRIMARY KEY,
+	command TEXT NOT NULL
+);

internal/store/usage.go

@@ -0,0 +1,43 @@
+package store
+
+import (
+	"context"
+	"database/sql"
+
+	"g.fc.run/ai/byre/internal/api"
+)
+
+func (s *Store) UsageCommands(ctx context.Context) (map[api.AgentSessionVendor]string, error) {
+	rows, err := s.db.QueryContext(ctx, `SELECT vendor, command FROM usage_commands`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	cmds := map[api.AgentSessionVendor]string{}
+	for rows.Next() {
+		vendor := ""
+		cmd := ""
+		err = rows.Scan(&vendor, &cmd)
+		if err != nil {
+			return nil, err
+		}
+		cmds[api.AgentSessionVendor(vendor)] = cmd
+	}
+	return cmds, rows.Err()
+}
+
+func (s *Store) SetUsageCommands(ctx context.Context, actor string, cmds map[api.AgentSessionVendor]string) error {
+	return s.write(ctx, func(tx *sql.Tx, emit emitFunc) error {
+		for vendor, cmd := range cmds {
+			_, err := tx.ExecContext(ctx, `
+				INSERT INTO usage_commands (vendor, command) VALUES (?, ?)
+				ON CONFLICT (vendor) DO UPDATE SET command = excluded.command
+			`, string(vendor), cmd)
+			if err != nil {
+				return err
+			}
+		}
+		return emit(api.Event{Kind: "admin.usage_commands", Actor: actor, Payload: map[string]any{}})
+	})
+}