diff --git a/packages/svelte/messages/compile-errors/attributes.md b/packages/svelte/messages/compile-errors/attributes.md
index 239b71a43c..9501080ee0 100644
--- a/packages/svelte/messages/compile-errors/attributes.md
+++ b/packages/svelte/messages/compile-errors/attributes.md
@@ -48,7 +48,7 @@ Cannot use `%type%:` alongside existing `%existing%:` directive
 
 ## invalid_let_directive_placement
 
-TODO
+`let:` directive at invalid position
 
 ## invalid_style_directive_modifier
 
diff --git a/packages/svelte/messages/compile-errors/css.md b/packages/svelte/messages/compile-errors/css.md
index 02acd29e5a..a14eb8c190 100644
--- a/packages/svelte/messages/compile-errors/css.md
+++ b/packages/svelte/messages/compile-errors/css.md
@@ -52,4 +52,4 @@ Nesting selectors can only be used inside a rule
 
 ## invalid_css_declaration
 
-TODO
+Declaration cannot be empty
diff --git a/packages/svelte/src/compiler/errors.js b/packages/svelte/src/compiler/errors.js
index 0dfee4ec16..32bb014105 100644
--- a/packages/svelte/src/compiler/errors.js
+++ b/packages/svelte/src/compiler/errors.js
@@ -173,7 +173,7 @@ export function transition_conflict(node, type, existing) {
  * @returns {never}
  */
 export function invalid_let_directive_placement(node) {
-	e(node, "invalid_let_directive_placement", "TODO");
+	e(node, "invalid_let_directive_placement", "`let:` directive at invalid position");
 }
 
 /**
@@ -436,7 +436,7 @@ export function invalid_nesting_selector(node) {
  * @returns {never}
  */
 export function invalid_css_declaration(node) {
-	e(node, "invalid_css_declaration", "TODO");
+	e(node, "invalid_css_declaration", "Declaration cannot be empty");
 }
 
 /**
diff --git a/packages/svelte/src/compiler/phases/1-parse/state/element.js b/packages/svelte/src/compiler/phases/1-parse/state/element.js
index 78988af6d1..619f1703ad 100644
--- a/packages/svelte/src/compiler/phases/1-parse/state/element.js
+++ b/packages/svelte/src/compiler/phases/1-parse/state/element.js
@@ -738,12 +738,12 @@ function read_sequence(parser, done, location) {
 				const index = parser.index - 1;
 				parser.eat('#');
 				const name = parser.read_until(/[^a-z]/);
-				e.invalid_block_placement(index, location, name);
+				e.invalid_block_placement(index, name, location);
 			} else if (parser.match('@')) {
 				const index = parser.index - 1;
 				parser.eat('@');
 				const name = parser.read_until(/[^a-z]/);
-				e.invalid_tag_placement(index, location, name);
+				e.invalid_tag_placement(index, name, location);
 			}
 
 			flush(parser.index - 1);
diff --git a/packages/svelte/src/compiler/phases/2-analyze/validation.js b/packages/svelte/src/compiler/phases/2-analyze/validation.js
index 7a416a2af0..86be1146a3 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/validation.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/validation.js
@@ -187,14 +187,17 @@ function validate_element(node, context) {
 			}
 		} else if (attribute.type === 'TransitionDirective') {
 			const existing = /** @type {import('#compiler').TransitionDirective | null} */ (
-				attribute.intro ? in_transition : out_transition
+				(attribute.intro && in_transition) || (attribute.outro && out_transition)
 			);
 
-			if (existing !== null) {
-				if (attribute.name === existing.name) {
-					e.transition_duplicate(attribute, attribute.name);
+			if (existing) {
+				const a = existing.intro ? (existing.outro ? 'transition' : 'in') : 'out';
+				const b = attribute.intro ? (attribute.outro ? 'transition' : 'in') : 'out';
+
+				if (a === b) {
+					e.transition_duplicate(attribute, a);
 				} else {
-					e.transition_conflict(attribute, attribute.name, existing.name);
+					e.transition_conflict(attribute, a, b);
 				}
 			}
 
@@ -205,7 +208,7 @@ function validate_element(node, context) {
 			let conflicting_passive_modifier = '';
 			for (const modifier of attribute.modifiers) {
 				if (!EventModifiers.includes(modifier)) {
-					const list = `${EventModifiers.slice(0, 1)} or ${EventModifiers.at(-1)}`;
+					const list = `${EventModifiers.slice(0, -1).join(', ')} or ${EventModifiers.at(-1)}`;
 					e.invalid_event_modifier(attribute, list);
 				}
 				if (modifier === 'passive') {
@@ -451,7 +454,7 @@ const validation = {
 					if (!contenteditable) {
 						e.missing_contenteditable_attribute(node);
 					} else if (!is_text_attribute(contenteditable) && contenteditable.value !== true) {
-						e.dynamic_contenteditable_attribute(node);
+						e.dynamic_contenteditable_attribute(contenteditable);
 					}
 				}
 			} else {
@@ -459,7 +462,7 @@ const validation = {
 				if (match) {
 					const property = binding_properties[match];
 					if (!property.valid_elements || property.valid_elements.includes(parent.name)) {
-						e.bind_invalid_detailed(node, node.name, ` Did you mean '${match}'?`);
+						e.bind_invalid_detailed(node, node.name, `Did you mean '${match}'?`);
 					}
 				}
 				e.bind_invalid(node, node.name);
@@ -1026,6 +1029,8 @@ function validate_no_const_assignment(node, argument, scope, is_binding) {
 			// TODO have a more specific error message for assignments to things like `{:then foo}`
 			const thing = 'constant';
 
+			console.log(binding);
+
 			if (is_binding) {
 				e.invalid_binding(node, thing);
 			} else {
diff --git a/packages/svelte/tests/validator/samples/animation-duplicate/errors.json b/packages/svelte/tests/validator/samples/animation-duplicate/errors.json
index 487196fc8f..03229646be 100644
--- a/packages/svelte/tests/validator/samples/animation-duplicate/errors.json
+++ b/packages/svelte/tests/validator/samples/animation-duplicate/errors.json
@@ -1,6 +1,6 @@
 [
 	{
-		"code": "duplicate_animation",
+		"code": "animation_duplicate",
 		"message": "An element can only have one 'animate' directive",
 		"start": {
 			"line": 7,
diff --git a/packages/svelte/tests/validator/samples/animation-not-in-each/errors.json b/packages/svelte/tests/validator/samples/animation-not-in-each/errors.json
index cbb4fab4c4..2b5f73585d 100644
--- a/packages/svelte/tests/validator/samples/animation-not-in-each/errors.json
+++ b/packages/svelte/tests/validator/samples/animation-not-in-each/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "invalid_animation",
-		"message": "An element that uses the animate directive must be the immediate child of a keyed each block",
+		"code": "animation_invalid_placement",
+		"message": "An element that uses the `animate:` directive must be the only child of a keyed `{#each ...}` block",
 		"start": {
 			"line": 5,
 			"column": 5
diff --git a/packages/svelte/tests/validator/samples/animation-not-in-keyed-each/errors.json b/packages/svelte/tests/validator/samples/animation-not-in-keyed-each/errors.json
index 4e4423dfa7..945376a1b1 100644
--- a/packages/svelte/tests/validator/samples/animation-not-in-keyed-each/errors.json
+++ b/packages/svelte/tests/validator/samples/animation-not-in-keyed-each/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "invalid_animation",
-		"message": "An element that uses the animate directive must be used inside a keyed each block. Did you forget to add a key to your each block?",
+		"code": "animation_missing_key",
+		"message": "An element that uses the `animate:` directive must be the only child of a keyed `{#each ...}` block. Did you forget to add a key to your each block?",
 		"start": {
 			"line": 6,
 			"column": 6
diff --git a/packages/svelte/tests/validator/samples/animation-siblings/errors.json b/packages/svelte/tests/validator/samples/animation-siblings/errors.json
index 46648d96fc..b6412ebca4 100644
--- a/packages/svelte/tests/validator/samples/animation-siblings/errors.json
+++ b/packages/svelte/tests/validator/samples/animation-siblings/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "invalid_animation",
-		"message": "An element that uses the animate directive must be the sole child of a keyed each block",
+		"code": "animation_invalid_placement",
+		"message": "An element that uses the `animate:` directive must be the only child of a keyed `{#each ...}` block",
 		"start": {
 			"line": 6,
 			"column": 6
diff --git a/packages/svelte/tests/validator/samples/binding-await-catch/errors.json b/packages/svelte/tests/validator/samples/binding-await-catch/errors.json
index c2acbb2e8d..93dea97135 100644
--- a/packages/svelte/tests/validator/samples/binding-await-catch/errors.json
+++ b/packages/svelte/tests/validator/samples/binding-await-catch/errors.json
@@ -1,6 +1,6 @@
 [
 	{
-		"code": "invalid_assignment",
+		"code": "invalid_binding",
 		"message": "Invalid binding to const variable ($derived values, let: directives, :then/:catch variables and @const declarations count as const)",
 		"start": {
 			"line": 6,
diff --git a/packages/svelte/tests/validator/samples/binding-await-then-2/errors.json b/packages/svelte/tests/validator/samples/binding-await-then-2/errors.json
index f0f4a7a3fd..71a45827e8 100644
--- a/packages/svelte/tests/validator/samples/binding-await-then-2/errors.json
+++ b/packages/svelte/tests/validator/samples/binding-await-then-2/errors.json
@@ -1,6 +1,6 @@
 [
 	{
-		"code": "invalid_assignment",
+		"code": "invalid_binding",
 		"message": "Invalid binding to const variable ($derived values, let: directives, :then/:catch variables and @const declarations count as const)",
 		"start": {
 			"line": 6,
diff --git a/packages/svelte/tests/validator/samples/binding-await-then/errors.json b/packages/svelte/tests/validator/samples/binding-await-then/errors.json
index c4f6009c78..ebc7ee5114 100644
--- a/packages/svelte/tests/validator/samples/binding-await-then/errors.json
+++ b/packages/svelte/tests/validator/samples/binding-await-then/errors.json
@@ -1,6 +1,6 @@
 [
 	{
-		"code": "invalid_assignment",
+		"code": "invalid_binding",
 		"message": "Invalid binding to const variable ($derived values, let: directives, :then/:catch variables and @const declarations count as const)",
 		"start": {
 			"line": 5,
diff --git a/packages/svelte/tests/validator/samples/binding-const/errors.json b/packages/svelte/tests/validator/samples/binding-const/errors.json
index 213a0808f7..d2f8b1a8b3 100644
--- a/packages/svelte/tests/validator/samples/binding-const/errors.json
+++ b/packages/svelte/tests/validator/samples/binding-const/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "invalid_assignment",
-		"message": "Invalid binding to const variable",
+		"code": "invalid_binding",
+		"message": "Cannot bind to constant",
 		"start": {
 			"line": 5,
 			"column": 7
diff --git a/packages/svelte/tests/validator/samples/binding-invalid-foreign-namespace/errors.json b/packages/svelte/tests/validator/samples/binding-invalid-foreign-namespace/errors.json
index 0049ed5359..de997e5394 100644
--- a/packages/svelte/tests/validator/samples/binding-invalid-foreign-namespace/errors.json
+++ b/packages/svelte/tests/validator/samples/binding-invalid-foreign-namespace/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "bind_invalid_target",
-		"message": "'value' is not a valid binding. Foreign elements only support bind:this",
+		"code": "bind_invalid_detailed",
+		"message": "`bind:value` is not a valid binding. Foreign elements only support `bind:this`",
 		"start": {
 			"line": 6,
 			"column": 7
diff --git a/packages/svelte/tests/validator/samples/binding-invalid/errors.json b/packages/svelte/tests/validator/samples/binding-invalid/errors.json
index 280360c625..9e0e455eaf 100644
--- a/packages/svelte/tests/validator/samples/binding-invalid/errors.json
+++ b/packages/svelte/tests/validator/samples/binding-invalid/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "bind_invalid_target",
-		"message": "'whatever' is not a valid binding",
+		"code": "bind_invalid",
+		"message": "`bind:whatever` is not a valid binding",
 		"start": {
 			"line": 5,
 			"column": 5
diff --git a/packages/svelte/tests/validator/samples/binding-let/errors.json b/packages/svelte/tests/validator/samples/binding-let/errors.json
index a133cbd1ea..cee8dd0177 100644
--- a/packages/svelte/tests/validator/samples/binding-let/errors.json
+++ b/packages/svelte/tests/validator/samples/binding-let/errors.json
@@ -1,6 +1,6 @@
 [
 	{
-		"code": "invalid_assignment",
+		"code": "invalid_binding",
 		"message": "Invalid binding to const variable ($derived values, let: directives, :then/:catch variables and @const declarations count as const)",
 		"start": {
 			"line": 6,
diff --git a/packages/svelte/tests/validator/samples/component-event-modifiers-invalid/errors.json b/packages/svelte/tests/validator/samples/component-event-modifiers-invalid/errors.json
index 275f5c5b07..14288a1385 100644
--- a/packages/svelte/tests/validator/samples/component-event-modifiers-invalid/errors.json
+++ b/packages/svelte/tests/validator/samples/component-event-modifiers-invalid/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"message": "Event modifiers other than 'once' can only be used on DOM elements",
-		"code": "invalid_event_modifier",
+		"code": "invalid_component_event_modifier",
 		"start": {
 			"line": 6,
 			"column": 8
diff --git a/packages/svelte/tests/validator/samples/component-slot-default-reserved/errors.json b/packages/svelte/tests/validator/samples/component-slot-default-reserved/errors.json
index 0f4af538a4..190c4d81a2 100644
--- a/packages/svelte/tests/validator/samples/component-slot-default-reserved/errors.json
+++ b/packages/svelte/tests/validator/samples/component-slot-default-reserved/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "invalid_slot_name",
-		"message": "default is a reserved word — it cannot be used as a slot name",
+		"code": "invalid_slot_name_default",
+		"message": "`default` is a reserved word — it cannot be used as a slot name",
 		"start": {
 			"line": 1,
 			"column": 6
diff --git a/packages/svelte/tests/validator/samples/const-tag-conflict-1/errors.json b/packages/svelte/tests/validator/samples/const-tag-conflict-1/errors.json
index d63fcd88e7..07c6cbadca 100644
--- a/packages/svelte/tests/validator/samples/const-tag-conflict-1/errors.json
+++ b/packages/svelte/tests/validator/samples/const-tag-conflict-1/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "duplicate_declaration",
-		"message": "'a' has already been declared",
+		"message": "`a` has already been declared",
 		"start": {
 			"line": 7,
 			"column": 10
diff --git a/packages/svelte/tests/validator/samples/const-tag-conflict-2/errors.json b/packages/svelte/tests/validator/samples/const-tag-conflict-2/errors.json
index f7df4a21c4..543f2a0217 100644
--- a/packages/svelte/tests/validator/samples/const-tag-conflict-2/errors.json
+++ b/packages/svelte/tests/validator/samples/const-tag-conflict-2/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "duplicate_declaration",
-		"message": "'item' has already been declared",
+		"message": "`item` has already been declared",
 		"start": {
 			"line": 6,
 			"column": 10
diff --git a/packages/svelte/tests/validator/samples/const-tag-readonly-2/errors.json b/packages/svelte/tests/validator/samples/const-tag-readonly-2/errors.json
index eb6c7390aa..87e9234fbe 100644
--- a/packages/svelte/tests/validator/samples/const-tag-readonly-2/errors.json
+++ b/packages/svelte/tests/validator/samples/const-tag-readonly-2/errors.json
@@ -1,6 +1,6 @@
 [
 	{
-		"code": "invalid_assignment",
+		"code": "invalid_binding",
 		"message": "Invalid binding to const variable ($derived values, let: directives, :then/:catch variables and @const declarations count as const)",
 		"start": {
 			"line": 7,
diff --git a/packages/svelte/tests/validator/samples/dollar-dollar-global-in-markup/errors.json b/packages/svelte/tests/validator/samples/dollar-dollar-global-in-markup/errors.json
index ec2497f40e..630f8c5ea2 100644
--- a/packages/svelte/tests/validator/samples/dollar-dollar-global-in-markup/errors.json
+++ b/packages/svelte/tests/validator/samples/dollar-dollar-global-in-markup/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "illegal_global",
-		"message": "$$billsyall is an illegal variable name. To reference a global variable called $$billsyall, use globalThis.$$billsyall",
+		"message": "`$$billsyall` is an illegal variable name. To reference a global variable called `$$billsyall`, use `globalThis.$$billsyall`",
 		"start": {
 			"line": 1,
 			"column": 1
diff --git a/packages/svelte/tests/validator/samples/dollar-dollar-global-in-script/errors.json b/packages/svelte/tests/validator/samples/dollar-dollar-global-in-script/errors.json
index 85ad4c6df9..5876bcae80 100644
--- a/packages/svelte/tests/validator/samples/dollar-dollar-global-in-script/errors.json
+++ b/packages/svelte/tests/validator/samples/dollar-dollar-global-in-script/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "illegal_global",
-		"message": "$$billsyall is an illegal variable name. To reference a global variable called $$billsyall, use globalThis.$$billsyall",
+		"message": "`$$billsyall` is an illegal variable name. To reference a global variable called `$$billsyall`, use `globalThis.$$billsyall`",
 		"start": {
 			"line": 2,
 			"column": 1
diff --git a/packages/svelte/tests/validator/samples/dollar-global-in-markup/errors.json b/packages/svelte/tests/validator/samples/dollar-global-in-markup/errors.json
index c7231a3915..1623518ca0 100644
--- a/packages/svelte/tests/validator/samples/dollar-global-in-markup/errors.json
+++ b/packages/svelte/tests/validator/samples/dollar-global-in-markup/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "illegal_global",
-		"message": "$ is an illegal variable name. To reference a global variable called $, use globalThis.$",
+		"message": "`$` is an illegal variable name. To reference a global variable called `$`, use `globalThis.$`",
 		"start": {
 			"line": 1,
 			"column": 1
diff --git a/packages/svelte/tests/validator/samples/dollar-global-in-script/errors.json b/packages/svelte/tests/validator/samples/dollar-global-in-script/errors.json
index e1909896e6..5d33dc3d83 100644
--- a/packages/svelte/tests/validator/samples/dollar-global-in-script/errors.json
+++ b/packages/svelte/tests/validator/samples/dollar-global-in-script/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "illegal_global",
-		"message": "$ is an illegal variable name. To reference a global variable called $, use globalThis.$",
+		"message": "`$` is an illegal variable name. To reference a global variable called `$`, use `globalThis.$`",
 		"start": {
 			"line": 2,
 			"column": 1
diff --git a/packages/svelte/tests/validator/samples/dynamic-element-missing-tag/errors.json b/packages/svelte/tests/validator/samples/dynamic-element-missing-tag/errors.json
index 615138f3b0..d31bd1964c 100644
--- a/packages/svelte/tests/validator/samples/dynamic-element-missing-tag/errors.json
+++ b/packages/svelte/tests/validator/samples/dynamic-element-missing-tag/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "missing_svelte_element_definition",
-		"message": "<svelte:element> must have a 'this' attribute",
+		"message": "`<svelte:element>` must have a 'this' attribute",
 		"start": {
 			"line": 2,
 			"column": 1
diff --git a/packages/svelte/tests/validator/samples/illegal-variable-declaration/errors.json b/packages/svelte/tests/validator/samples/illegal-variable-declaration/errors.json
index 61f0ad0fed..d55986ec5a 100644
--- a/packages/svelte/tests/validator/samples/illegal-variable-declaration/errors.json
+++ b/packages/svelte/tests/validator/samples/illegal-variable-declaration/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "illegal_variable_declaration",
-		"message": "Cannot declare same variable name which is imported inside <script context=\"module\">",
+		"message": "Cannot declare same variable name which is imported inside `<script context=\"module\">`",
 		"start": {
 			"line": 12,
 			"column": 5
diff --git a/packages/svelte/tests/validator/samples/let-directive/errors.json b/packages/svelte/tests/validator/samples/let-directive/errors.json
index fe5bf7f41a..5e4138812e 100644
--- a/packages/svelte/tests/validator/samples/let-directive/errors.json
+++ b/packages/svelte/tests/validator/samples/let-directive/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "invalid_let_directive_placement",
-		"message": "let directive at invalid position",
+		"message": "`let:` directive at invalid position",
 		"start": {
 			"line": 6,
 			"column": 15
diff --git a/packages/svelte/tests/validator/samples/multiple-script-default-context/errors.json b/packages/svelte/tests/validator/samples/multiple-script-default-context/errors.json
index 6bf421e270..ab06795527 100644
--- a/packages/svelte/tests/validator/samples/multiple-script-default-context/errors.json
+++ b/packages/svelte/tests/validator/samples/multiple-script-default-context/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "duplicate_script_element",
-		"message": "A component can have a single top-level <script> element and/or a single top-level <script context=\"module\"> element",
+		"message": "A component can have a single top-level `<script>` element and/or a single top-level `<script context=\"module\">` element",
 		"start": {
 			"line": 5,
 			"column": 0
diff --git a/packages/svelte/tests/validator/samples/multiple-script-module-context/errors.json b/packages/svelte/tests/validator/samples/multiple-script-module-context/errors.json
index 6bf421e270..ab06795527 100644
--- a/packages/svelte/tests/validator/samples/multiple-script-module-context/errors.json
+++ b/packages/svelte/tests/validator/samples/multiple-script-module-context/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "duplicate_script_element",
-		"message": "A component can have a single top-level <script> element and/or a single top-level <script context=\"module\"> element",
+		"message": "A component can have a single top-level `<script>` element and/or a single top-level `<script context=\"module\">` element",
 		"start": {
 			"line": 5,
 			"column": 0
diff --git a/packages/svelte/tests/validator/samples/namespace-invalid/errors.json b/packages/svelte/tests/validator/samples/namespace-invalid/errors.json
index df8639c039..e381545dc0 100644
--- a/packages/svelte/tests/validator/samples/namespace-invalid/errors.json
+++ b/packages/svelte/tests/validator/samples/namespace-invalid/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "invalid_svelte_option_namespace",
-		"message": "Unsupported <svelte:option> value for \"namespace\". Valid values are \"html\", \"svg\" or \"foreign\".",
+		"message": "Unsupported `<svelte:option>` value for \"namespace\". Valid values are \"html\", \"svg\" or \"foreign\"",
 		"start": {
 			"line": 1,
 			"column": 16
diff --git a/packages/svelte/tests/validator/samples/namespace-non-literal/errors.json b/packages/svelte/tests/validator/samples/namespace-non-literal/errors.json
index 36a35167a8..f8b2c75f05 100644
--- a/packages/svelte/tests/validator/samples/namespace-non-literal/errors.json
+++ b/packages/svelte/tests/validator/samples/namespace-non-literal/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "invalid_svelte_option_namespace",
-		"message": "Unsupported <svelte:option> value for \"namespace\". Valid values are \"html\", \"svg\" or \"foreign\".",
+		"message": "Unsupported `<svelte:option>` value for \"namespace\". Valid values are \"html\", \"svg\" or \"foreign\"",
 		"start": {
 			"line": 1,
 			"column": 16
diff --git a/packages/svelte/tests/validator/samples/svelte-fragment-placement-2/errors.json b/packages/svelte/tests/validator/samples/svelte-fragment-placement-2/errors.json
index 8415450c90..cf34adc56b 100644
--- a/packages/svelte/tests/validator/samples/svelte-fragment-placement-2/errors.json
+++ b/packages/svelte/tests/validator/samples/svelte-fragment-placement-2/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "invalid_svelte_fragment_placement",
-		"message": "<svelte:fragment> must be the direct child of a component",
+		"message": "`<svelte:fragment>` must be the direct child of a component",
 		"start": {
 			"line": 5,
 			"column": 0
diff --git a/packages/svelte/tests/validator/samples/svelte-fragment-placement/errors.json b/packages/svelte/tests/validator/samples/svelte-fragment-placement/errors.json
index 1760c1b8c4..195b0fca19 100644
--- a/packages/svelte/tests/validator/samples/svelte-fragment-placement/errors.json
+++ b/packages/svelte/tests/validator/samples/svelte-fragment-placement/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "invalid_svelte_fragment_placement",
-		"message": "<svelte:fragment> must be the direct child of a component",
+		"message": "`<svelte:fragment>` must be the direct child of a component",
 		"start": {
 			"line": 7,
 			"column": 2
diff --git a/packages/svelte/tests/validator/samples/svelte-head-attributes/errors.json b/packages/svelte/tests/validator/samples/svelte-head-attributes/errors.json
index 7debd1dfa2..f230f20788 100644
--- a/packages/svelte/tests/validator/samples/svelte-head-attributes/errors.json
+++ b/packages/svelte/tests/validator/samples/svelte-head-attributes/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "illegal_svelte_head_attribute",
-		"message": "<svelte:head> cannot have attributes nor directives",
+		"message": "`<svelte:head>` cannot have attributes nor directives",
 		"start": {
 			"line": 1,
 			"column": 13
diff --git a/packages/svelte/tests/validator/samples/tag-invalid/errors.json b/packages/svelte/tests/validator/samples/tag-invalid/errors.json
index 506420fbc2..84d7f49de6 100644
--- a/packages/svelte/tests/validator/samples/tag-invalid/errors.json
+++ b/packages/svelte/tests/validator/samples/tag-invalid/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "invalid_tag_property",
-		"message": "tag name must be two or more words joined by the \"-\" character",
+		"message": "Tag name must be two or more words joined by the \"-\" character",
 		"start": {
 			"line": 1,
 			"column": 16
diff --git a/packages/svelte/tests/validator/samples/textarea-value-children/errors.json b/packages/svelte/tests/validator/samples/textarea-value-children/errors.json
index 955a4180d0..e2ea3e48fc 100644
--- a/packages/svelte/tests/validator/samples/textarea-value-children/errors.json
+++ b/packages/svelte/tests/validator/samples/textarea-value-children/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "invalid_textarea_content",
-		"message": "A <textarea> can have either a value attribute or (equivalently) child content, but not both",
+		"message": "A `<textarea>` can have either a value attribute or (equivalently) child content, but not both",
 		"start": {
 			"line": 1,
 			"column": 0
diff --git a/packages/svelte/tests/validator/samples/title-no-attributes/errors.json b/packages/svelte/tests/validator/samples/title-no-attributes/errors.json
index bb2d90a334..85768c1fa9 100644
--- a/packages/svelte/tests/validator/samples/title-no-attributes/errors.json
+++ b/packages/svelte/tests/validator/samples/title-no-attributes/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "illegal_title_attribute",
-		"message": "<title> cannot have attributes nor directives",
+		"message": "`<title>` cannot have attributes nor directives",
 		"start": {
 			"line": 2,
 			"column": 8
diff --git a/packages/svelte/tests/validator/samples/title-no-children/errors.json b/packages/svelte/tests/validator/samples/title-no-children/errors.json
index 7ecd375438..6a4d2475e1 100644
--- a/packages/svelte/tests/validator/samples/title-no-children/errors.json
+++ b/packages/svelte/tests/validator/samples/title-no-children/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "invalid_title_content",
-		"message": "<title> can only contain text and {tags}",
+		"message": "`<title>` can only contain text and {tags}",
 		"start": {
 			"line": 2,
 			"column": 11
diff --git a/packages/svelte/tests/validator/samples/transition-duplicate-in-transition/errors.json b/packages/svelte/tests/validator/samples/transition-duplicate-in-transition/errors.json
index 22029dc956..f4d13f4f54 100644
--- a/packages/svelte/tests/validator/samples/transition-duplicate-in-transition/errors.json
+++ b/packages/svelte/tests/validator/samples/transition-duplicate-in-transition/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "transition_conflict",
-		"message": "An element cannot have both an 'in' directive and a 'transition' directive",
+		"message": "Cannot use `in:` alongside existing `transition:` directive",
 		"start": {
 			"line": 6,
 			"column": 12
diff --git a/packages/svelte/tests/validator/samples/transition-duplicate-in/errors.json b/packages/svelte/tests/validator/samples/transition-duplicate-in/errors.json
index e78ad7d93d..1f1690d256 100644
--- a/packages/svelte/tests/validator/samples/transition-duplicate-in/errors.json
+++ b/packages/svelte/tests/validator/samples/transition-duplicate-in/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "transition_conflict",
-		"message": "An element can only have one 'in' directive",
+		"code": "transition_duplicate",
+		"message": "Cannot use multiple `in:` directives on a single element",
 		"start": {
 			"line": 6,
 			"column": 12
diff --git a/packages/svelte/tests/validator/samples/transition-duplicate-out-transition/errors.json b/packages/svelte/tests/validator/samples/transition-duplicate-out-transition/errors.json
index 6501881182..16e4e09e8d 100644
--- a/packages/svelte/tests/validator/samples/transition-duplicate-out-transition/errors.json
+++ b/packages/svelte/tests/validator/samples/transition-duplicate-out-transition/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "transition_conflict",
-		"message": "An element cannot have both an 'out' directive and a 'transition' directive",
+		"message": "Cannot use `out:` alongside existing `transition:` directive",
 		"start": {
 			"line": 6,
 			"column": 13
diff --git a/packages/svelte/tests/validator/samples/transition-duplicate-out/errors.json b/packages/svelte/tests/validator/samples/transition-duplicate-out/errors.json
index 4017396ad2..1dd1acde96 100644
--- a/packages/svelte/tests/validator/samples/transition-duplicate-out/errors.json
+++ b/packages/svelte/tests/validator/samples/transition-duplicate-out/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "transition_conflict",
-		"message": "An element can only have one 'out' directive",
+		"code": "transition_duplicate",
+		"message": "Cannot use multiple `out:` directives on a single element",
 		"start": {
 			"line": 6,
 			"column": 13
diff --git a/packages/svelte/tests/validator/samples/transition-duplicate-transition-in/errors.json b/packages/svelte/tests/validator/samples/transition-duplicate-transition-in/errors.json
index ba088b2b21..89c6414100 100644
--- a/packages/svelte/tests/validator/samples/transition-duplicate-transition-in/errors.json
+++ b/packages/svelte/tests/validator/samples/transition-duplicate-transition-in/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "transition_conflict",
-		"message": "An element cannot have both a 'transition' directive and an 'in' directive",
+		"message": "Cannot use `transition:` alongside existing `in:` directive",
 		"start": {
 			"line": 6,
 			"column": 20
diff --git a/packages/svelte/tests/validator/samples/transition-duplicate-transition-out/errors.json b/packages/svelte/tests/validator/samples/transition-duplicate-transition-out/errors.json
index 2d62376e2a..3f0cbc0eee 100644
--- a/packages/svelte/tests/validator/samples/transition-duplicate-transition-out/errors.json
+++ b/packages/svelte/tests/validator/samples/transition-duplicate-transition-out/errors.json
@@ -1,7 +1,7 @@
 [
 	{
 		"code": "transition_conflict",
-		"message": "An element cannot have both a 'transition' directive and an 'out' directive",
+		"message": "Cannot use `transition:` alongside existing `out:` directive",
 		"start": {
 			"line": 6,
 			"column": 20
diff --git a/packages/svelte/tests/validator/samples/transition-duplicate-transition/errors.json b/packages/svelte/tests/validator/samples/transition-duplicate-transition/errors.json
index 45f6df33f6..6e9d2f900a 100644
--- a/packages/svelte/tests/validator/samples/transition-duplicate-transition/errors.json
+++ b/packages/svelte/tests/validator/samples/transition-duplicate-transition/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "transition_conflict",
-		"message": "An element can only have one 'transition' directive",
+		"code": "transition_duplicate",
+		"message": "Cannot use multiple `transition:` directives on a single element",
 		"start": {
 			"line": 6,
 			"column": 20
diff --git a/packages/svelte/tests/validator/samples/window-binding-invalid-innerwidth/errors.json b/packages/svelte/tests/validator/samples/window-binding-invalid-innerwidth/errors.json
index 7d5c019464..99a1c892d3 100644
--- a/packages/svelte/tests/validator/samples/window-binding-invalid-innerwidth/errors.json
+++ b/packages/svelte/tests/validator/samples/window-binding-invalid-innerwidth/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "bind_invalid_target",
-		"message": "'innerwidth' is not a valid binding (did you mean 'innerWidth'?)",
+		"code": "bind_invalid_detailed",
+		"message": "`bind:innerwidth` is not a valid binding. Did you mean 'innerWidth'?",
 		"start": {
 			"line": 5,
 			"column": 15
diff --git a/packages/svelte/tests/validator/samples/window-binding-invalid/errors.json b/packages/svelte/tests/validator/samples/window-binding-invalid/errors.json
index 52bb5451c0..fc6c219444 100644
--- a/packages/svelte/tests/validator/samples/window-binding-invalid/errors.json
+++ b/packages/svelte/tests/validator/samples/window-binding-invalid/errors.json
@@ -1,7 +1,7 @@
 [
 	{
-		"code": "bind_invalid_target",
-		"message": "'potato' is not a valid binding",
+		"code": "bind_invalid",
+		"message": "`bind:potato` is not a valid binding",
 		"start": {
 			"line": 5,
 			"column": 15