feat(canary): mysql generator + register in registry

Phase 8 third commit. Closes the generator set — all 7 token types are
now registered.

mysql/generator.go:
  - Generator with publicHost / publicPort / database fields. New()
    returns localhost:3306/internal_db defaults; NewWithAddress(host,
    port) overrides for Phase 9 wire-up
  - Generate writes mysql_username into t.Metadata (json.RawMessage
    merge via setMySQLUsername helper — same defensive map[string]
    json.RawMessage pattern as envfile's extractIncludeKeys: malformed
    existing metadata is replaced rather than erroring, existing
    fields preserved, prior mysql_username overwritten)
  - Returns Artifact{Kind: KindConnectionString, ConnectionString:
    "mysql://canary_<id>@<host>:<port>/internal_db"} per spec §9.7
    lines 1345-1352. baseURL ignored (mysql connection strings don't
    use it)
  - Trigger(ctx, t, r) returns (nil, nil, ErrHTTPTriggerNotSupported)
    sentinel error — mysql triggers fire over the TCP listener (see
    server.go/handler.go), not via the HTTP router. Phase 9's router
    will not mount any HTTP route to mysql.Trigger; this is defense
    for accidental programmatic calls
  - Note on spec §9.7 line 1343: `t.Metadata["mysql_username"] =
    username` doesn't compile against the real Token.Metadata
    (json.RawMessage). The setMySQLUsername helper is the sanctioned
    *string-shape adaptation, matching the slowredirect/envfile
    metadata patterns

mysql/generator_test.go (~11 cases):
  - Type / KindConnectionString / default connection string format /
    custom address / canary_ prefix invariant / metadata persistence
    on empty token / preservation of existing metadata fields /
    malformed-metadata fallback / stale-mysql_username overwrite /
    baseURL ignored / Trigger returns ErrHTTPTriggerNotSupported with
    nil event + nil response

registry update: cardinality 6 → 7; pending list now empty.
TestBuild_AllSevenGeneratorsRegistered replaces the
TypesPresentInPhaseN test pattern from prior phases, asserting all 7
generator types are present (closes the generator set; future phases
add services/handlers, not generators).

DEFERRED TO PHASE 9 (task 8.5): wiring `go mysql.Run(ctx, addr,
handler)` into cmd/canary/main.go. The handoff anti-relitigation set
documents "Phase 9 wires the registry into main.go" — the mysql
listener goroutine fits naturally into Phase 9's main.go work
alongside config.Config.MySQL.Enabled, config.Config.MySQL.Addr,
the token.Service (for TokenLookup), and the event.Service (for
EventRecorder). Wiring it in Phase 8 would require partial config
additions that Phase 9 then re-touches.

Pre-rollup acceptance gate clean at HEAD:
  - go build ./... + go vet ./... clean
  - go test -race -timeout=60s ./... all packages pass (~115 tests
    added across Phase 8 alone)
  - go test -tags=integration -race -timeout=300s pass
  - golangci-lint run ./... → 0 issues.
  - zero //nolint pragmas anywhere

PROJECTS/beginner/canary-token-generator/backend/internal/token/generators/mysql/generator.go

@@ -0,0 +1,103 @@
+// ©AngelaMos | 2026
+// generator.go
+
+package mysql
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/event"
+	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token"
+	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators"
+)
+
+const (
+	defaultPublicHost = "localhost"
+	defaultPublicPort = 3306
+	defaultDatabase   = "internal_db"
+
+	connectionStringFmt = "mysql://%s@%s:%d/%s"
+)
+
+type Generator struct {
+	publicHost string
+	publicPort int
+	database   string
+}
+
+func New() *Generator {
+	return NewWithAddress(defaultPublicHost, defaultPublicPort)
+}
+
+func NewWithAddress(host string, port int) *Generator {
+	return &Generator{
+		publicHost: host,
+		publicPort: port,
+		database:   defaultDatabase,
+	}
+}
+
+func (g *Generator) Type() token.Type { return token.TypeMySQL }
+
+func (g *Generator) Generate(
+	_ context.Context,
+	t *token.Token,
+	_ string,
+) (generators.Artifact, error) {
+	username := mysqlUsernamePrefix + t.ID
+
+	newMeta, err := setMySQLUsername(t.Metadata, username)
+	if err != nil {
+		return generators.Artifact{}, fmt.Errorf(
+			"mysql: persist username: %w",
+			err,
+		)
+	}
+	t.Metadata = newMeta
+
+	connStr := fmt.Sprintf(
+		connectionStringFmt,
+		username,
+		g.publicHost,
+		g.publicPort,
+		g.database,
+	)
+
+	return generators.Artifact{
+		Kind:             generators.KindConnectionString,
+		ConnectionString: connStr,
+	}, nil
+}
+
+func (g *Generator) Trigger(
+	_ context.Context,
+	_ *token.Token,
+	_ *http.Request,
+) (*event.Event, *generators.TriggerResponse, error) {
+	return nil, nil, ErrHTTPTriggerNotSupported
+}
+
+func setMySQLUsername(
+	metadata json.RawMessage,
+	username string,
+) (json.RawMessage, error) {
+	m := make(map[string]json.RawMessage)
+	if len(metadata) > 0 {
+		if err := json.Unmarshal(metadata, &m); err != nil {
+			m = make(map[string]json.RawMessage)
+		}
+	}
+	val, err := json.Marshal(username)
+	if err != nil {
+		return nil, fmt.Errorf("marshal mysql_username: %w", err)
+	}
+	m[extraMySQLUsername] = val
+	out, err := json.Marshal(m)
+	if err != nil {
+		return nil, fmt.Errorf("marshal merged metadata: %w", err)
+	}
+	return out, nil
+}

PROJECTS/beginner/canary-token-generator/backend/internal/token/generators/mysql/generator_test.go

@@ -0,0 +1,191 @@
+// ©AngelaMos | 2026
+// generator_test.go
+
+package mysql_test
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token"
+	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators"
+	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/mysql"
+)
+
+func newMySQLToken(id string) *token.Token {
+	return &token.Token{
+		ID:           id,
+		ManageID:     "manage-" + id,
+		Type:         token.TypeMySQL,
+		Memo:         "unit test mysql",
+		AlertChannel: token.ChannelWebhook,
+		Enabled:      true,
+	}
+}
+
+func TestGenerator_TypeIsMySQL(t *testing.T) {
+	require.Equal(t, token.TypeMySQL, mysql.New().Type())
+}
+
+func TestGenerate_ArtifactKindIsConnectionString(t *testing.T) {
+	g := mysql.New()
+	art, err := g.Generate(context.Background(), newMySQLToken("abc"), "")
+	require.NoError(t, err)
+	require.Equal(t, generators.KindConnectionString, art.Kind)
+}
+
+func TestGenerate_ConnectionStringDefaultLocalhost(t *testing.T) {
+	g := mysql.New()
+	art, err := g.Generate(context.Background(), newMySQLToken("abc"), "")
+	require.NoError(t, err)
+	require.Equal(
+		t,
+		"mysql://canary_abc@localhost:3306/internal_db",
+		art.ConnectionString,
+	)
+}
+
+func TestGenerate_ConnectionStringCustomAddress(t *testing.T) {
+	g := mysql.NewWithAddress("canary.example.com", 13306)
+	art, err := g.Generate(context.Background(), newMySQLToken("xyz"), "")
+	require.NoError(t, err)
+	require.Equal(
+		t,
+		"mysql://canary_xyz@canary.example.com:13306/internal_db",
+		art.ConnectionString,
+	)
+}
+
+func TestGenerate_UsernamePrefixIsCanary_(t *testing.T) {
+	g := mysql.New()
+	art, err := g.Generate(context.Background(), newMySQLToken("probeid"), "")
+	require.NoError(t, err)
+	require.Contains(
+		t,
+		art.ConnectionString,
+		"canary_probeid@",
+		"username must be canary_+token.ID for TCP-side lookup parity",
+	)
+}
+
+func TestGenerate_PersistsMySQLUsernameInMetadata(t *testing.T) {
+	g := mysql.New()
+	tok := newMySQLToken("abc")
+	require.Empty(t, tok.Metadata, "fresh token has no metadata yet")
+
+	_, err := g.Generate(context.Background(), tok, "")
+	require.NoError(t, err)
+
+	require.NotEmpty(
+		t,
+		tok.Metadata,
+		"Generate must persist mysql_username into token metadata",
+	)
+
+	var m map[string]any
+	require.NoError(t, json.Unmarshal(tok.Metadata, &m))
+	require.Equal(t, "canary_abc", m["mysql_username"])
+}
+
+func TestGenerate_PreservesExistingMetadataFields(t *testing.T) {
+	g := mysql.New()
+	tok := newMySQLToken("abc")
+	tok.Metadata = json.RawMessage(`{"existing_field":"keep_me","other":42}`)
+
+	_, err := g.Generate(context.Background(), tok, "")
+	require.NoError(t, err)
+
+	var m map[string]any
+	require.NoError(t, json.Unmarshal(tok.Metadata, &m))
+	require.Equal(t, "keep_me", m["existing_field"])
+	other, ok := m["other"].(float64)
+	require.True(t, ok)
+	require.Equal(t, 42, int(other))
+	require.Equal(t, "canary_abc", m["mysql_username"])
+}
+
+func TestGenerate_MalformedMetadataIsReplaced(t *testing.T) {
+	g := mysql.New()
+	tok := newMySQLToken("abc")
+	tok.Metadata = json.RawMessage(`{not valid json`)
+
+	_, err := g.Generate(context.Background(), tok, "")
+	require.NoError(
+		t,
+		err,
+		"malformed metadata must not block generation — replace with a fresh map",
+	)
+
+	var m map[string]any
+	require.NoError(t, json.Unmarshal(tok.Metadata, &m))
+	require.Equal(t, "canary_abc", m["mysql_username"])
+}
+
+func TestGenerate_OverwritesPriorMySQLUsername(t *testing.T) {
+	g := mysql.New()
+	tok := newMySQLToken("abc")
+	tok.Metadata = json.RawMessage(`{"mysql_username":"stale_value"}`)
+
+	_, err := g.Generate(context.Background(), tok, "")
+	require.NoError(t, err)
+
+	var m map[string]any
+	require.NoError(t, json.Unmarshal(tok.Metadata, &m))
+	require.Equal(
+		t,
+		"canary_abc",
+		m["mysql_username"],
+		"regeneration must overwrite stale mysql_username with the current token's",
+	)
+}
+
+func TestGenerate_BaseURLIgnored(t *testing.T) {
+	g := mysql.New()
+
+	art1, err := g.Generate(
+		context.Background(),
+		newMySQLToken("abc"),
+		"https://canary.example.com",
+	)
+	require.NoError(t, err)
+	art2, err := g.Generate(
+		context.Background(),
+		newMySQLToken("abc"),
+		"https://different.example.com/sub",
+	)
+	require.NoError(t, err)
+	require.Equal(
+		t,
+		art1.ConnectionString,
+		art2.ConnectionString,
+		"baseURL is irrelevant to mysql connection strings",
+	)
+}
+
+func TestTrigger_ReturnsHTTPNotSupportedError(t *testing.T) {
+	g := mysql.New()
+	r := httptest.NewRequest(http.MethodGet, "/c/abc", nil)
+
+	evt, resp, err := g.Trigger(
+		context.Background(),
+		newMySQLToken("abc"),
+		r,
+	)
+	require.Error(t, err)
+	require.ErrorIs(t, err, mysql.ErrHTTPTriggerNotSupported)
+	require.Nil(t, evt, "no event when HTTP-triggered (mysql uses TCP)")
+	require.Nil(t, resp, "no response when HTTP-triggered (mysql uses TCP)")
+}
+
+func TestTrigger_NilTokenAlsoReturnsHTTPNotSupportedError(t *testing.T) {
+	g := mysql.New()
+	r := httptest.NewRequest(http.MethodGet, "/c/abc", nil)
+
+	_, _, err := g.Trigger(context.Background(), nil, r)
+	require.ErrorIs(t, err, mysql.ErrHTTPTriggerNotSupported)
+}

PROJECTS/beginner/canary-token-generator/backend/internal/token/generators/registry/registry.go

@@ -9,6 +9,7 @@ import (
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/docx"
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/envfile"
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/kubeconfig"
+	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/mysql"
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/pdf"
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/slowredirect"
 	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/webbug"
@@ -28,5 +29,6 @@ func Build(_ Config) Registry {
 		token.TypePDF:          pdf.New(),
 		token.TypeKubeconfig:   kubeconfig.New(),
 		token.TypeEnvfile:      envfile.New(),
+		token.TypeMySQL:        mysql.New(),
 	}
 }

PROJECTS/beginner/canary-token-generator/backend/internal/token/generators/registry/registry_test.go

@@ -62,6 +62,14 @@ func TestBuild_RegistersEnvfile(t *testing.T) {
 	require.Equal(t, token.TypeEnvfile, g.Type())
 }
 
+func TestBuild_RegistersMySQL(t *testing.T) {
+	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
+	g, ok := reg[token.TypeMySQL]
+	require.True(t, ok, "expected mysql generator registered")
+	require.NotNil(t, g)
+	require.Equal(t, token.TypeMySQL, g.Type())
+}
+
 func TestBuild_UnknownTypeReturnsZeroValue(t *testing.T) {
 	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
 	g, ok := reg["nonexistent-type"]
@@ -69,28 +77,25 @@ func TestBuild_UnknownTypeReturnsZeroValue(t *testing.T) {
 	require.Nil(t, g, "map zero value for missing key must be nil interface")
 }
 
-func TestBuild_PendingTypesNotYetRegistered(t *testing.T) {
-	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
-	pending := []token.Type{
-		token.TypeMySQL,
-	}
-	for _, tt := range pending {
-		_, ok := reg[tt]
-		require.False(
-			t,
-			ok,
-			"type %q is not yet registered (subsequent phases will add it); registry must not claim it",
-			tt,
-		)
-	}
-}
-
-func TestBuild_OnlyExpectedTypesPresentInPhase7(t *testing.T) {
+func TestBuild_AllSevenGeneratorsRegistered(t *testing.T) {
 	reg := registry.Build(registry.Config{BaseURL: testBaseURL})
 	require.Len(
 		t,
 		reg,
-		6,
-		"Phase 7 registers exactly six generators (webbug, slowredirect, docx, pdf, kubeconfig, envfile); other phases append",
+		7,
+		"Phase 8 closes the generator set with all 7 types registered (webbug, slowredirect, docx, pdf, kubeconfig, envfile, mysql)",
 	)
+
+	for _, ty := range []token.Type{
+		token.TypeWebbug,
+		token.TypeSlowRedirect,
+		token.TypeDocx,
+		token.TypePDF,
+		token.TypeKubeconfig,
+		token.TypeEnvfile,
+		token.TypeMySQL,
+	} {
+		_, ok := reg[ty]
+		require.True(t, ok, "type %q must be registered", ty)
+	}
 }