diff --git a/apps/docs/docs/architecture/diagnostic-conventions.md b/apps/docs/docs/architecture/diagnostic-conventions.md
index 32f1850a..d78ff8ec 100644
--- a/apps/docs/docs/architecture/diagnostic-conventions.md
+++ b/apps/docs/docs/architecture/diagnostic-conventions.md
@@ -109,9 +109,9 @@ General-purpose factory for schema validation diagnostics. Accepts a `Range`, `S
 
 Parser-level errors only. Source is always `'parser'`. Code must be `'syntax-error'` or `'missing-token'`.
 
-### `undefinedReferenceDiagnostic(range, message, referenceName, suggestion?, expected?)`
+### `undefinedReferenceDiagnostic(range, message, referenceName, found, suggestion?, expected?)`
 
-For undefined reference errors. Automatically appends "Did you mean?" hints via `formatSuggestionHint()`.
+For undefined reference errors. Automatically appends "Did you mean?" hints via `formatSuggestionHint()`. `found` is the misspelled segment (used by the LSP quick fix).
 
 ### `typeMismatchDiagnostic(range, message, expectedType, actualType, source?)`
 
diff --git a/dialect/agentfabric/src/lint/passes/rules/undefined-reference.ts b/dialect/agentfabric/src/lint/passes/rules/undefined-reference.ts
index fd032fc6..642e2d24 100644
--- a/dialect/agentfabric/src/lint/passes/rules/undefined-reference.ts
+++ b/dialect/agentfabric/src/lint/passes/rules/undefined-reference.ts
@@ -571,6 +571,7 @@ function formatResolutionDiagnostic(
         range,
         `'${property}' is not defined in ${namespace}`,
         referenceName,
+        property,
         suggestion,
         result.members
       );
@@ -582,6 +583,7 @@ function formatResolutionDiagnostic(
         range,
         `'@${namespace}' is not a recognized namespace`,
         referenceName,
+        namespace,
         suggestion,
         result.knownNamespaces
       );
@@ -592,7 +594,8 @@ function formatResolutionDiagnostic(
         range,
         `'@${namespace}' cannot be used as a reference. ` +
           `This namespace is scoped to its parent block and is not directly referenceable`,
-        referenceName
+        referenceName,
+        namespace
       );
 
     case 'colinear-miss': {
@@ -601,6 +604,7 @@ function formatResolutionDiagnostic(
         range,
         `'${property}' is not defined in ${namespace}`,
         referenceName,
+        property,
         suggestion,
         result.members
       );
@@ -612,6 +616,7 @@ function formatResolutionDiagnostic(
         range,
         `'${property}' is not defined in ${namespace}`,
         referenceName,
+        property,
         suggestion,
         result.candidates
       );
diff --git a/packages/language/src/core/diagnostics.ts b/packages/language/src/core/diagnostics.ts
index ea48a478..1838f15d 100644
--- a/packages/language/src/core/diagnostics.ts
+++ b/packages/language/src/core/diagnostics.ts
@@ -58,6 +58,7 @@ export function undefinedReferenceDiagnostic(
   range: Range,
   message: string,
   referenceName: string,
+  found: string,
   suggestion?: string,
   expected?: string[]
 ): Diagnostic {
@@ -70,6 +71,7 @@ export function undefinedReferenceDiagnostic(
     source: 'agentscript-lint',
     data: {
       referenceName,
+      found,
       ...(suggestion ? { suggestion } : {}),
       ...(expected && expected.length > 0 ? { expected } : {}),
     },
diff --git a/packages/language/src/lint/undefined-reference.ts b/packages/language/src/lint/undefined-reference.ts
index 3b99a303..03ab1a6f 100644
--- a/packages/language/src/lint/undefined-reference.ts
+++ b/packages/language/src/lint/undefined-reference.ts
@@ -607,6 +607,7 @@ function formatResolutionDiagnostic(
         range,
         `'${property}' is not defined in ${namespace}`,
         referenceName,
+        property,
         suggestion,
         result.members
       );
@@ -618,6 +619,7 @@ function formatResolutionDiagnostic(
         range,
         `'@${namespace}' is not a recognized namespace`,
         referenceName,
+        namespace,
         suggestion,
         result.knownNamespaces
       );
@@ -628,7 +630,8 @@ function formatResolutionDiagnostic(
         range,
         `'@${namespace}' cannot be used as a reference. ` +
           `This namespace is scoped to its parent block and is not directly referenceable`,
-        referenceName
+        referenceName,
+        namespace
       );
 
     case 'colinear-miss': {
@@ -637,6 +640,7 @@ function formatResolutionDiagnostic(
         range,
         `'${property}' is not defined in ${namespace}`,
         referenceName,
+        property,
         suggestion,
         result.members
       );
@@ -648,6 +652,7 @@ function formatResolutionDiagnostic(
         range,
         `'${property}' is not defined in ${namespace}`,
         referenceName,
+        property,
         suggestion,
         result.candidates
       );
@@ -802,6 +807,7 @@ function resolveNestedGlobalCheck(
     cst.range,
     `'${check.member}' is not defined in ${namespaceLabel}`,
     referenceName,
+    check.member,
     suggestion,
     members
   );
@@ -840,6 +846,7 @@ function resolveListElementAttrCheck(
     cst.range,
     `'${check.attr}' is not defined on ${namespaceLabel} elements`,
     referenceName,
+    check.attr,
     suggestion,
     members
   );
diff --git a/packages/lsp/src/providers/code-actions.test.ts b/packages/lsp/src/providers/code-actions.test.ts
index 9e3d90f2..94941813 100644
--- a/packages/lsp/src/providers/code-actions.test.ts
+++ b/packages/lsp/src/providers/code-actions.test.ts
@@ -403,3 +403,57 @@ access:
     expect(config).not.toContain('default_agent_user');
   });
 });
+
+/** Return the undefined-reference quick fixes offered for `source`. */
+function getUndefinedReferenceActions(source: string) {
+  const state = createState(source);
+  const diags = state.diagnostics.filter(d => d.code === 'undefined-reference');
+  const actions = provideCodeActions(
+    state,
+    { start: { line: 0, character: 0 }, end: { line: 0, character: 0 } },
+    diags
+  );
+  return { diags, actions };
+}
+
+describe('undefined-reference quick-fix', () => {
+  const agent = (ref: string) => `config:
+    developer_name: "agent"
+    agent_type: "AgentforceServiceAgent"
+
+variables:
+    customer_name: string = ""
+
+start_agent topic_selector:
+    description: "route"
+    reasoning:
+        instructions: ->
+            | Hello {!${ref}}
+`;
+
+  test('replaces a misspelled member', () => {
+    const source = agent('@variables.custmer_name');
+    const { actions } = getUndefinedReferenceActions(source);
+    expect(actions).toHaveLength(1);
+    expect(actions[0].title).toBe("Change to 'customer_name'");
+    const edits = Object.values(actions[0].edit!.changes!)[0];
+    expect(applyEdits(source, edits)).toBe(agent('@variables.customer_name'));
+  });
+
+  test('replaces a misspelled namespace', () => {
+    const source = agent('@varibles.customer_name');
+    const { actions } = getUndefinedReferenceActions(source);
+    expect(actions).toHaveLength(1);
+    expect(actions[0].title).toBe("Change to 'variables'");
+    const edits = Object.values(actions[0].edit!.changes!)[0];
+    expect(applyEdits(source, edits)).toBe(agent('@variables.customer_name'));
+  });
+
+  test('offers nothing when there is no close match', () => {
+    const { diags, actions } = getUndefinedReferenceActions(
+      agent('@variables.zzzzzzzz')
+    );
+    expect(diags).toHaveLength(1);
+    expect(actions).toHaveLength(0);
+  });
+});
diff --git a/packages/lsp/src/providers/code-actions.ts b/packages/lsp/src/providers/code-actions.ts
index cca0d3f4..4c63cb1f 100644
--- a/packages/lsp/src/providers/code-actions.ts
+++ b/packages/lsp/src/providers/code-actions.ts
@@ -295,6 +295,58 @@ export function provideCodeActions(
         });
       }
 
+      // Quick fix for a misspelled `@namespace.member` reference. The range
+      // covers the whole reference, so only the misspelled segment is replaced:
+      // the namespace (right after the `@`) or the last member.
+      if (diagnostic.code === 'undefined-reference') {
+        const found = diagnostic.data?.found as string | undefined;
+        const suggestion = diagnostic.data?.suggestion as string | undefined;
+        const referenceName = diagnostic.data?.referenceName as
+          | string
+          | undefined;
+        if (!found || !suggestion || !referenceName) continue;
+
+        const { start, end } = diagnostic.range;
+        if (start.line !== end.line) continue;
+
+        // `@foo.foo` can't tell the namespace from the member; offer nothing.
+        if (referenceName === `@${found}.${found}`) continue;
+        const isNamespace = referenceName.startsWith(`@${found}.`);
+        const foundStart = isNamespace
+          ? start.character + 1
+          : end.character - found.length;
+        const line = source.split('\n')[start.line];
+        if (
+          line === undefined ||
+          line.slice(foundStart, foundStart + found.length) !== found
+        ) {
+          continue;
+        }
+
+        actions.push({
+          title: `Change to '${suggestion}'`,
+          kind: CodeActionKind.QuickFix,
+          diagnostics: [diagnostic],
+          isPreferred: true,
+          edit: {
+            changes: {
+              [uri]: [
+                {
+                  range: {
+                    start: { line: start.line, character: foundStart },
+                    end: {
+                      line: start.line,
+                      character: foundStart + found.length,
+                    },
+                  },
+                  newText: suggestion,
+                },
+              ],
+            },
+          },
+        });
+      }
+
       // Quick fix for unknown dialect — offer each available dialect
       if (diagnostic.code === 'unknown-dialect') {
         const availableNames = diagnostic.data?.availableNames as