feat: support optional flag rename governance to #85349380

docs/cli-interface-flag-migrations.md

@@ -1,6 +1,6 @@
 # CLI flag 兼容迁移治理
 
-本文定义一种受控迁移：保留旧 flag 的可执行兼容性，但把它从 Help 与 Agent Schema 中隐藏，并将新的规范 flag 提升为必填。它只解决这一种精确变更，不是通用 breaking-change 豁免。
+本文定义一种受控迁移：保留旧 flag 的可执行兼容性，但把它从 Help 与 Agent Schema 中隐藏，并将新的规范 flag 设为唯一可见入口。迁移必须保持原 flag 的 requiredness：optional 只能迁到 optional，required 只能迁到 required。它只解决这一种精确变更，不是通用 breaking-change 豁免。
 
 同名 flag 的精确类型迁移属于另一类评审机制，只能进入
 `internal/interfacesnapshot/reviewed.go` 与 legacy smoke helper 的镜像表；flag rename
@@ -50,7 +50,7 @@ scripts/policy/interface-migrations/approved-flag-migrations-v1.json
 | 阶段 | PR 可以做什么 | 必须满足的快照状态 |
 |---|---|---|
 | 1. 治理审批 | 新增 `state: pending` 的精确记录；不得在同一个 PR 修改产品 surface | candidate 和 merge-base 都与记录中的 `before` 完全一致；该记录不改变 stable 的判断 |
-| 2. 产品迁移 | merge-base 已拥有 `pending` 后，按记录一次性切到精确 `after`，并把记录改为 `state: consumed` | legacy 仍存在但由 visible 变 hidden，且声明 `alias_of`；canonical 达到记录的必填状态 |
+| 2. 产品迁移 | merge-base 已拥有 `pending` 后，按记录一次性切到精确 `after`，并把记录改为 `state: consumed` | legacy 仍存在但由 visible 变 hidden，且声明 `alias_of`；canonical 的 requiredness 与 legacy 迁移前完全一致 |
 | 3. 保留回执 | 产品 PR 合入后，如果 stable 仍是 `before`，继续保留 `consumed` | merge-base 或 stable 仍有任一份尚未达到 `after` |
 | 4. 单独清理 | 当 merge-base 和 stable 都已经是 `after`，在后续 PR 删除该记录 | 两份参考快照均精确匹配 `after`；继续保留过期回执会被门禁拒绝 |
 
@@ -122,7 +122,7 @@ scripts/policy/interface-migrations/approved-flag-migrations-v1.json
 一条 base-owned、状态正确且前后快照精确匹配的记录，只会从普通兼容报告中移除以下两类预期 finding：
 
 1. legacy flag 的 `flag_became_hidden`（visible → hidden）；
-2. canonical flag 的 `required_flag_added`（新增时即必填）或 `flag_became_required`（已有 flag 从可选变必填）。
+2. required legacy 被新增的 required canonical 替代时产生的 `required_flag_added`。已有 canonical 的 requiredness 不允许借 rename 改变。
 
 以下变化仍按普通兼容规则阻塞，不能被迁移记录掩盖：
 
@@ -145,7 +145,7 @@ legacy 名改为 canonical 名。Schema adapter 只接受已经由三方 Interfa
   `required` / `cli_required` 或重写 constraint；
 - rename 前后的 `type`、`property`、`interface_type`、default、format、enum 与
   `required_when` 必须完全一致；
-- `required` / `cli_required` 只能保持不变或按审批从 `false` 提升为 `true`，禁止降低；
+- `required` / `cli_required` 必须在 rename 前后完全一致，升高或降低都失败；
 - constraint 只允许在同一 tool 内按已枚举的 legacy → canonical map 做 member 替换、
   排序与去重；group kind、非迁移 member 或 group 增删仍然阻塞；
 - 多个 legacy 指向同一 canonical 时，所有历史 parameter signature 必须一致，否则

internal/interfacesnapshot/migrations.go

@@ -324,11 +324,20 @@ func (m FlagMigration) validate() error {
 	if m.Canonical.After.Hidden {
 		return fmt.Errorf("canonical flag must remain visible")
 	}
-	if !m.Canonical.After.Required {
-		return fmt.Errorf("canonical flag must be required after migration")
+	// Requiredness belongs to the one logical parameter. The hidden legacy
+	// spelling must not remain independently required, while the canonical
+	// spelling inherits the exact before-state contract. If the canonical flag
+	// already existed, a rename receipt cannot authorize changing it either.
+	if m.Legacy.After.Required {
+		return fmt.Errorf("legacy compatibility alias must not remain independently required after migration")
 	}
-	if m.Canonical.Before.Present && m.Canonical.Before.Required {
-		return fmt.Errorf("canonical flag must be absent or optional before migration")
+	if m.Legacy.Before.Required != m.Canonical.After.Required {
+		return fmt.Errorf(
+			"flag requiredness must be preserved from legacy before to canonical after",
+		)
+	}
+	if m.Canonical.Before.Present && m.Canonical.Before.Required != m.Canonical.After.Required {
+		return fmt.Errorf("canonical flag requiredness must remain unchanged when already present")
 	}
 	if m.Legacy.After.AliasOf != m.Canonical.Name {
 		return fmt.Errorf(
@@ -681,12 +690,6 @@ func flagMigrationAuthorizesChange(
 			change.Kind == "required_flag_added" {
 			return true
 		}
-		if migration.Canonical.Before.Present &&
-			!migration.Canonical.Before.Required &&
-			migration.Canonical.After.Required &&
-			change.Kind == "flag_became_required" {
-			return true
-		}
 	}
 	return false
 }

internal/interfacesnapshot/migrations_coverage_test.go

@@ -188,7 +188,7 @@ func TestCrossPlatformCoverageFlagMigrationManifestParserEdges(t *testing.T) {
 
 func TestCrossPlatformCoverageFlagMigrationManifestRejectsEveryContractDrift(t *testing.T) {
 	optionalCanonical := func() FlagMigrationManifest {
-		manifest := coverageManifest(FlagMigrationPending)
+		manifest := coverageOptionalManifest(FlagMigrationPending)
 		manifest.Migrations[0].Canonical.Before = FlagMigrationState{
 			Present: true,
 			Type:    "string",
@@ -269,6 +269,36 @@ func TestCrossPlatformCoverageFlagMigrationManifestRejectsEveryContractDrift(t *
 			mutate:  func(m *FlagMigrationManifest) { m.Migrations[0].Canonical.After = FlagMigrationState{} },
 			wantErr: "canonical flag must be present after migration",
 		},
+		{
+			name:    "required legacy cannot become optional canonical",
+			make:    func() FlagMigrationManifest { return coverageManifest(FlagMigrationPending) },
+			mutate:  func(m *FlagMigrationManifest) { m.Migrations[0].Canonical.After.Required = false },
+			wantErr: "requiredness must be preserved from legacy before to canonical after",
+		},
+		{
+			name:    "optional legacy cannot become required canonical",
+			make:    func() FlagMigrationManifest { return coverageOptionalManifest(FlagMigrationPending) },
+			mutate:  func(m *FlagMigrationManifest) { m.Migrations[0].Canonical.After.Required = true },
+			wantErr: "requiredness must be preserved from legacy before to canonical after",
+		},
+		{
+			name: "existing canonical cannot change requiredness",
+			make: func() FlagMigrationManifest { return coverageManifest(FlagMigrationPending) },
+			mutate: func(manifest *FlagMigrationManifest) {
+				manifest.Migrations[0].Canonical.Before = FlagMigrationState{
+					Present: true,
+					Type:    "string",
+					Scope:   "local",
+				}
+			},
+			wantErr: "canonical flag requiredness must remain unchanged when already present",
+		},
+		{
+			name:    "hidden legacy alias is not independently required",
+			make:    func() FlagMigrationManifest { return coverageManifest(FlagMigrationPending) },
+			mutate:  func(m *FlagMigrationManifest) { m.Migrations[0].Legacy.After.Required = true },
+			wantErr: "legacy compatibility alias must not remain independently required",
+		},
 		{
 			name:    "legacy after declares alias target",
 			make:    func() FlagMigrationManifest { return coverageManifest(FlagMigrationPending) },
@@ -711,8 +741,32 @@ func TestCrossPlatformCoverageCompareAllWithFlagMigrationsInheritedAndOptionalCa
 		}
 	})
 
-	t.Run("existing optional canonical becomes required", func(t *testing.T) {
-		pending := coverageManifest(FlagMigrationPending)
+	t.Run("optional canonical is introduced without becoming required", func(t *testing.T) {
+		pending := coverageOptionalManifest(FlagMigrationPending)
+		consumed := coverageOptionalManifest(FlagMigrationConsumed)
+		before := coverageMigrationSnapshot(pending.Migrations[0], false, false)
+		after := coverageMigrationSnapshot(pending.Migrations[0], true, false)
+
+		ordinary := Compare(after, before, "merge-base")
+		if !hasFlagChange(ordinary.Blocking, "flag_became_hidden", pending.Migrations[0].Command, pending.Migrations[0].Legacy.Name) {
+			t.Fatalf("fixture did not create flag_became_hidden: %#v", ordinary.Blocking)
+		}
+		if hasFlagChange(ordinary.Blocking, "required_flag_added", pending.Migrations[0].Command, pending.Migrations[0].Canonical.Name) {
+			t.Fatalf("optional canonical was treated as required: %#v", ordinary.Blocking)
+		}
+		report, err := CompareAllWithFlagMigrations(
+			after,
+			map[string]Snapshot{"merge-base": before, "stable": before},
+			pending,
+			consumed,
+		)
+		if err != nil || !report.Compatible {
+			t.Fatalf("optional rename = (%#v, %v), want compatible", report, err)
+		}
+	})
+
+	t.Run("existing optional canonical remains optional", func(t *testing.T) {
+		pending := coverageOptionalManifest(FlagMigrationPending)
 		pending.Migrations[0].Canonical.Before = FlagMigrationState{
 			Present: true,
 			Type:    "string",
@@ -725,8 +779,8 @@ func TestCrossPlatformCoverageCompareAllWithFlagMigrationsInheritedAndOptionalCa
 		after := coverageMigrationSnapshot(pending.Migrations[0], true, false)
 
 		ordinary := Compare(after, before, "merge-base")
-		if !hasFlagChange(ordinary.Blocking, "flag_became_required", pending.Migrations[0].Command, pending.Migrations[0].Canonical.Name) {
-			t.Fatalf("fixture did not create flag_became_required: %#v", ordinary.Blocking)
+		if hasFlagChange(ordinary.Blocking, "flag_became_required", pending.Migrations[0].Command, pending.Migrations[0].Canonical.Name) {
+			t.Fatalf("fixture changed canonical requiredness: %#v", ordinary.Blocking)
 		}
 		report, err := CompareAllWithFlagMigrations(
 			after,
@@ -735,7 +789,54 @@ func TestCrossPlatformCoverageCompareAllWithFlagMigrationsInheritedAndOptionalCa
 			consumed,
 		)
 		if err != nil || !report.Compatible {
-			t.Fatalf("optional-to-required migration = (%#v, %v), want compatible", report, err)
+			t.Fatalf("existing optional canonical migration = (%#v, %v), want compatible", report, err)
+		}
+	})
+}
+
+func TestCrossPlatformCoverageOptionalFlagMigrationLifecycleRemainsHostile(t *testing.T) {
+	pending := coverageOptionalManifest(FlagMigrationPending)
+	consumed := coverageOptionalManifest(FlagMigrationConsumed)
+	empty := coverageEmptyManifest()
+	migration := pending.Migrations[0]
+	before := coverageMigrationSnapshot(migration, false, false)
+	after := coverageMigrationSnapshot(migration, true, false)
+
+	t.Run("candidate cannot self authorize", func(t *testing.T) {
+		_, err := CompareAllWithFlagMigrations(
+			after,
+			map[string]Snapshot{"merge-base": before, "stable": before},
+			empty,
+			pending,
+		)
+		if err == nil || !strings.Contains(err.Error(), "cannot authorize its own interface change") {
+			t.Fatalf("candidate self-authorization error = %v", err)
+		}
+	})
+
+	t.Run("partial application remains rejected", func(t *testing.T) {
+		partial := coverageMigrationSnapshot(migration, false, false)
+		partial.Commands[len(partial.Commands)-1].LocalFlags[0].Hidden = true
+		_, err := CompareAllWithFlagMigrations(
+			partial,
+			map[string]Snapshot{"merge-base": before, "stable": before},
+			pending,
+			consumed,
+		)
+		if err == nil || !strings.Contains(err.Error(), "partially applied flag migration") {
+			t.Fatalf("partial optional migration error = %v", err)
+		}
+	})
+
+	t.Run("consumed receipt remains stale after every reference converges", func(t *testing.T) {
+		_, err := CompareAllWithFlagMigrations(
+			after,
+			map[string]Snapshot{"merge-base": after, "stable": after},
+			consumed,
+			consumed,
+		)
+		if err == nil || !strings.Contains(err.Error(), "stale after all references reached the after state") {
+			t.Fatalf("stale optional migration error = %v", err)
 		}
 	})
 }
@@ -886,6 +987,13 @@ func coverageManifest(state string) FlagMigrationManifest {
 	}
 }
 
+func coverageOptionalManifest(state string) FlagMigrationManifest {
+	manifest := coverageManifest(state)
+	manifest.Migrations[0].Legacy.Before.Required = false
+	manifest.Migrations[0].Canonical.After.Required = false
+	return manifest
+}
+
 func coverageEmptyManifest() FlagMigrationManifest {
 	return FlagMigrationManifest{Version: FlagMigrationManifestVersion, Migrations: []FlagMigration{}}
 }

internal/interfacesnapshot/migrations_test.go

@@ -37,6 +37,21 @@ const validFlagMigrationManifestJSON = `{
   ]
 }`
 
+func optionalFlagMigrationManifestJSON() string {
+	manifest := strings.Replace(
+		validFlagMigrationManifestJSON,
+		`"before": {"present": true, "type": "string", "required": true, "scope": "local"}`,
+		`"before": {"present": true, "type": "string", "scope": "local"}`,
+		1,
+	)
+	return strings.Replace(
+		manifest,
+		`"after": {"present": true, "type": "string", "required": true, "scope": "local"}`,
+		`"after": {"present": true, "type": "string", "scope": "local"}`,
+		1,
+	)
+}
+
 func TestCrossPlatformCoverageReadFlagMigrationManifestRejectsUnknownFields(t *testing.T) {
 	_, err := ReadFlagMigrationManifest(strings.NewReader(`{
   "version": 1,
@@ -110,6 +125,9 @@ func TestCrossPlatformCoverageReadFlagMigrationManifestValidatesExactEntries(t *
 	if _, err := ReadFlagMigrationManifest(strings.NewReader(validFlagMigrationManifestJSON)); err != nil {
 		t.Fatalf("ReadFlagMigrationManifest(valid) error = %v", err)
 	}
+	if _, err := ReadFlagMigrationManifest(strings.NewReader(optionalFlagMigrationManifestJSON())); err != nil {
+		t.Fatalf("ReadFlagMigrationManifest(optional rename) error = %v", err)
+	}
 
 	tests := []struct {
 		name    string
@@ -162,24 +180,34 @@ func TestCrossPlatformCoverageReadFlagMigrationManifestValidatesExactEntries(t *
 			wantErr: "canonical flag must remain visible",
 		},
 		{
-			name: "canonical remains optional",
+			name: "required legacy becomes optional canonical",
 			input: strings.Replace(
 				validFlagMigrationManifestJSON,
 				`"after": {"present": true, "type": "string", "required": true, "scope": "local"}`,
 				`"after": {"present": true, "type": "string", "scope": "local"}`,
 				1,
 			),
-			wantErr: "canonical flag must be required after migration",
+			wantErr: "requiredness must be preserved from legacy before to canonical after",
 		},
 		{
-			name: "canonical was already required",
+			name: "optional legacy becomes required canonical",
+			input: strings.Replace(
+				optionalFlagMigrationManifestJSON(),
+				`"after": {"present": true, "type": "string", "scope": "local"}`,
+				`"after": {"present": true, "type": "string", "required": true, "scope": "local"}`,
+				1,
+			),
+			wantErr: "requiredness must be preserved from legacy before to canonical after",
+		},
+		{
+			name: "existing canonical changes requiredness",
 			input: strings.Replace(
 				validFlagMigrationManifestJSON,
 				`"before": {"present": false}`,
-				`"before": {"present": true, "type": "string", "required": true, "scope": "local"}`,
+				`"before": {"present": true, "type": "string", "scope": "local"}`,
 				1,
 			),
-			wantErr: "canonical flag must be absent or optional before migration",
+			wantErr: "canonical flag requiredness must remain unchanged when already present",
 		},
 	}
 
@@ -215,9 +243,10 @@ func TestCrossPlatformCoverageFlagMigrationManifestRejectsDuplicateAndInexactCon
 	canonicalDrift := manifest
 	canonicalDrift.Migrations = append([]FlagMigration(nil), manifest.Migrations...)
 	canonicalDrift.Migrations[0].Canonical.Before = FlagMigrationState{
-		Present: true,
-		Type:    "string",
-		Scope:   "local",
+		Present:  true,
+		Type:     "string",
+		Required: true,
+		Scope:    "local",
 	}
 	canonicalDrift.Migrations[0].Canonical.After.Type = "stringSlice"
 	if err := canonicalDrift.Validate(); err == nil || !strings.Contains(err.Error(), "canonical flag type") {

scripts/policy/schema-compat/main.go

@@ -1313,6 +1313,8 @@ func validateRenamedSchemaParameter(
 	oldParameter parameterSchema,
 	newParameter parameterSchema,
 ) error {
+	// The migration authorizes only the CLI spelling change. Requiredness is
+	// part of the parameter contract in both projections and must remain exact.
 	if oldParameter.Type != newParameter.Type ||
 		oldParameter.Property != newParameter.Property ||
 		oldParameter.InterfaceType != newParameter.InterfaceType ||
@@ -1328,17 +1330,17 @@ func validateRenamedSchemaParameter(
 			migration.Canonical.Name,
 		)
 	}
-	if oldParameter.Required && !newParameter.Required {
+	if oldParameter.Required != newParameter.Required {
 		return fmt.Errorf(
-			"approved flag migration %q Schema parameter %q -> %q became optional",
+			"approved flag migration %q Schema parameter %q -> %q changed requiredness",
 			migration.Command,
 			migration.Legacy.Name,
 			migration.Canonical.Name,
 		)
 	}
-	if oldParameter.CLIRequired && !newParameter.CLIRequired {
+	if oldParameter.CLIRequired != newParameter.CLIRequired {
 		return fmt.Errorf(
-			"approved flag migration %q Schema parameter %q -> %q stopped being cli_required",
+			"approved flag migration %q Schema parameter %q -> %q changed cli_required",
 			migration.Command,
 			migration.Legacy.Name,
 			migration.Canonical.Name,

scripts/policy/schema-compat/main_test.go

@@ -1218,8 +1218,11 @@ func TestCrossPlatformCoverageSchemaFlagMigrationNormalizesExactRename(t *testin
 			t.Fatalf("normalized baseline retained legacy parameter %q", legacy)
 		}
 	}
-	if canonical := tool.Parameters["conversation-id"]; !canonical.Required || !canonical.CLIRequired {
-		t.Fatalf("canonical required transition was not normalized: %#v", canonical)
+	if canonical := tool.Parameters["conversation-id"]; canonical.Required || canonical.CLIRequired {
+		t.Fatalf("optional canonical rename changed requiredness: %#v", canonical)
+	}
+	if canonical := tool.Parameters["message-id"]; !canonical.Required || !canonical.CLIRequired {
+		t.Fatalf("required canonical rename changed requiredness: %#v", canonical)
 	}
 	if tool.Constraints != current.Products["chat"].Tools["chat.edit_message"].Constraints {
 		t.Fatalf("constraints were not normalized: %s", tool.Constraints)
@@ -1269,6 +1272,39 @@ func TestCrossPlatformCoverageSchemaFlagMigrationRejectsSemanticDrift(t *testing
 			}
 		})
 	}
+
+	for _, test := range []struct {
+		name   string
+		want   string
+		mutate func(*parameterSchema)
+	}{
+		{name: "optional required promotion", want: "changed requiredness", mutate: func(parameter *parameterSchema) {
+			parameter.Required = true
+		}},
+		{name: "optional cli_required promotion", want: "changed cli_required", mutate: func(parameter *parameterSchema) {
+			parameter.CLIRequired = true
+		}},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			current := schemaFlagMigrationContract(true)
+			product := current.Products["chat"]
+			tool := product.Tools["chat.edit_message"]
+			canonical := tool.Parameters["conversation-id"]
+			test.mutate(&canonical)
+			tool.Parameters["conversation-id"] = canonical
+			product.Tools["chat.edit_message"] = tool
+			current.Products["chat"] = product
+
+			_, err := normalizeSchemaFlagMigrations(
+				schemaFlagMigrationContract(false),
+				current,
+				schemaFlagMigrationAuthorizations(),
+			)
+			if err == nil || !strings.Contains(err.Error(), test.want) {
+				t.Fatalf("normalizeSchemaFlagMigrations() error = %v, want %q", err, test.want)
+			}
+		})
+	}
 }
 
 func TestCrossPlatformCoverageSchemaFlagMigrationAdapterBranches(t *testing.T) {
@@ -1321,9 +1357,10 @@ func TestCrossPlatformCoverageSchemaFlagMigrationAdapterBranches(t *testing.T) {
 		t.Fatal("missing candidate product was normalized away")
 	}
 
-	canonicalOnly := schemaFlagMigrationAuthorizations()[0]
-	canonicalOnly.Legacy.Name = "legacy-not-published-in-schema"
-	driftedCanonical := cloneContract(current)
+	canonicalOnlyMigration := schemaFlagMigrationAuthorizations()[0]
+	canonicalOnlyMigration.Legacy.Name = "legacy-not-published-in-schema"
+	canonicalOnlyBaseline := schemaFlagMigrationContract(true)
+	driftedCanonical := cloneContract(canonicalOnlyBaseline)
 	product = driftedCanonical.Products["chat"]
 	tool = product.Tools["chat.edit_message"]
 	canonical := tool.Parameters["conversation-id"]
@@ -1331,7 +1368,7 @@ func TestCrossPlatformCoverageSchemaFlagMigrationAdapterBranches(t *testing.T) {
 	tool.Parameters["conversation-id"] = canonical
 	product.Tools["chat.edit_message"] = tool
 	driftedCanonical.Products["chat"] = product
-	normalized, err = normalizeSchemaFlagMigrations(baseline, driftedCanonical, []interfacesnapshot.FlagMigration{canonicalOnly})
+	normalized, err = normalizeSchemaFlagMigrations(canonicalOnlyBaseline, driftedCanonical, []interfacesnapshot.FlagMigration{canonicalOnlyMigration})
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1339,24 +1376,24 @@ func TestCrossPlatformCoverageSchemaFlagMigrationAdapterBranches(t *testing.T) {
 		t.Fatalf("canonical-only Schema drift was hidden: %s", failures)
 	}
 
-	canonicalOptional := schemaFlagMigrationContract(true)
-	product = canonicalOptional.Products["chat"]
+	promotedCanonical := cloneContract(canonicalOnlyBaseline)
+	product = promotedCanonical.Products["chat"]
 	tool = product.Tools["chat.edit_message"]
 	canonical = tool.Parameters["conversation-id"]
-	canonical.Required = false
-	canonical.CLIRequired = false
+	canonical.Required = true
+	canonical.CLIRequired = true
 	tool.Parameters["conversation-id"] = canonical
 	product.Tools["chat.edit_message"] = tool
-	canonicalOptional.Products["chat"] = product
+	promotedCanonical.Products["chat"] = product
 	normalized, err = normalizeSchemaFlagMigrations(
-		canonicalOptional,
-		schemaFlagMigrationContract(true),
-		[]interfacesnapshot.FlagMigration{canonicalOnly},
+		canonicalOnlyBaseline,
+		promotedCanonical,
+		[]interfacesnapshot.FlagMigration{canonicalOnlyMigration},
 	)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if failures := strings.Join(checkCompatibility(normalized, schemaFlagMigrationContract(true)), "\n"); !strings.Contains(failures, "newly required") || !strings.Contains(failures, "newly cli_required") {
+	if failures := strings.Join(checkCompatibility(normalized, promotedCanonical), "\n"); !strings.Contains(failures, "newly required") || !strings.Contains(failures, "newly cli_required") {
 		t.Fatalf("canonical-only required promotion was hidden: %s", failures)
 	}
 
@@ -1392,12 +1429,19 @@ func TestCrossPlatformCoverageSchemaFlagMigrationAdapterBranches(t *testing.T) {
 	}
 
 	old := parameterSchema{Required: true, CLIRequired: true}
-	if err := validateRenamedSchemaParameter(schemaFlagMigrationAuthorizations()[0], old, parameterSchema{CLIRequired: true}); err == nil || !strings.Contains(err.Error(), "became optional") {
+	if err := validateRenamedSchemaParameter(schemaFlagMigrationAuthorizations()[0], old, parameterSchema{CLIRequired: true}); err == nil || !strings.Contains(err.Error(), "changed requiredness") {
 		t.Fatalf("direct required decline error = %v", err)
 	}
-	if err := validateRenamedSchemaParameter(schemaFlagMigrationAuthorizations()[0], old, parameterSchema{Required: true}); err == nil || !strings.Contains(err.Error(), "stopped being cli_required") {
+	if err := validateRenamedSchemaParameter(schemaFlagMigrationAuthorizations()[0], old, parameterSchema{Required: true}); err == nil || !strings.Contains(err.Error(), "changed cli_required") {
 		t.Fatalf("direct cli_required decline error = %v", err)
 	}
+	optional := parameterSchema{}
+	if err := validateRenamedSchemaParameter(schemaFlagMigrationAuthorizations()[0], optional, parameterSchema{Required: true}); err == nil || !strings.Contains(err.Error(), "changed requiredness") {
+		t.Fatalf("direct required promotion error = %v", err)
+	}
+	if err := validateRenamedSchemaParameter(schemaFlagMigrationAuthorizations()[0], optional, parameterSchema{CLIRequired: true}); err == nil || !strings.Contains(err.Error(), "changed cli_required") {
+		t.Fatalf("direct cli_required promotion error = %v", err)
+	}
 }
 
 func TestCrossPlatformCoverageSchemaFlagMigrationRejectsPartialAndUnrelatedChanges(t *testing.T) {
@@ -1471,9 +1515,8 @@ func TestCrossPlatformCoverageSchemaFlagMigrationRejectsPartialAndUnrelatedChang
 		t.Fatalf("constraint rewrite without Schema parameter evidence was hidden: %s", failures)
 	}
 
-	// A baseline that already contains only the canonical parameter may receive
-	// a required promotion, but that is not evidence that a stray legacy name in
-	// constraints belongs to the migration.
+	// A baseline that already contains only the canonical parameter is not
+	// evidence that a stray legacy name in constraints belongs to the migration.
 	canonicalOnly := schemaFlagMigrationContract(true)
 	product = canonicalOnly.Products["chat"]
 	tool = product.Tools["chat.edit_message"]
@@ -1749,13 +1792,10 @@ func schemaFlagMigrationContract(after bool) schemaContract {
 		InterfaceType: "string",
 	}
 	parameters := map[string]parameterSchema{
-		"conversation-id": conversation,
-		"unrelated":       {Type: `"string"`, Property: "unrelated"},
+		"unrelated": {Type: `"string"`, Property: "unrelated"},
 	}
-	constraints := `{"require_one_of":[["conversation-id","group","id"]]}`
+	constraints := `{"require_one_of":[["group","id"]]}`
 	if after {
-		conversation.Required = true
-		conversation.CLIRequired = true
 		parameters["conversation-id"] = conversation
 		parameters["message-id"] = legacyMessage
 		constraints = `{"require_one_of":[["conversation-id"]]}`
@@ -1788,7 +1828,6 @@ func schemaFlagMigrationAuthorizations() []interfacesnapshot.FlagMigration {
 		Scope:   "local",
 	}
 	conversationAfter := conversationBefore
-	conversationAfter.Required = true
 	messageBefore := interfacesnapshot.FlagMigrationState{
 		Present:  true,
 		Type:     "string",
@@ -1808,7 +1847,7 @@ func schemaFlagMigrationAuthorizations() []interfacesnapshot.FlagMigration {
 			},
 			Canonical: interfacesnapshot.FlagMigrationSide{
 				Name:   "conversation-id",
-				Before: conversationBefore,
+				Before: interfacesnapshot.FlagMigrationState{},
 				After:  conversationAfter,
 			},
 		},
@@ -1823,7 +1862,7 @@ func schemaFlagMigrationAuthorizations() []interfacesnapshot.FlagMigration {
 			},
 			Canonical: interfacesnapshot.FlagMigrationSide{
 				Name:   "conversation-id",
-				Before: conversationBefore,
+				Before: interfacesnapshot.FlagMigrationState{},
 				After:  conversationAfter,
 			},
 		},