diff --git a/ql/lib/codeql/actions/Ast.qll b/ql/lib/codeql/actions/Ast.qll
index 2bbf5c8ac0d..881daf13336 100644
--- a/ql/lib/codeql/actions/Ast.qll
+++ b/ql/lib/codeql/actions/Ast.qll
@@ -2,7 +2,7 @@ private import codeql.actions.ast.internal.Actions
 private import codeql.Locations
 
 /**
- * Base class for the AST tree. Based on YamlNode from the Yaml library.
+ * Base class for thejAST tree. Based on YamlNode from the Yaml library.
  */
 class AstNode instanceof YamlNode {
   AstNode getParentNode() { result = super.getParentNode() }
@@ -14,20 +14,16 @@ class AstNode instanceof YamlNode {
   string getAPrimaryQlClass() { result = super.getAPrimaryQlClass() }
 
   Location getLocation() { result = super.getLocation() }
-}
-
-/**
- * A statement is a group of expressions and/or statements that you design to carry out a task or an action.
- * Any statement that can return a value is automatically qualified to be used as an expression.
- */
-class Statement extends AstNode {
-  /** Gets the workflow that this job is a part of. */
-  WorkflowStmt getEnclosingWorkflowStmt() { this = result.getAChildNode*() }
 
   /**
-   * Gets a environment variable expression by name in the scope of the current step.
+   * Gets the enclosing workflow statement.
    */
-  Expression getEnvExpr(string name) {
+  Workflow getEnclosingWorkflow() { this = result.getAChildNode*() }
+
+  /**
+   * Gets a environment variable expression by name in the scope of the current node.
+   */
+  EnvExpr getEnvExpr(string name) {
     exists(Actions::Env env |
       env.(YamlMapping).maps(any(YamlScalar s | s.getValue() = name), result)
     |
@@ -40,37 +36,32 @@ class Statement extends AstNode {
   }
 }
 
-/**
- * An expression is any word or group of words or symbols that is a value. In programming, an expression is a value, or anything that executes and ends up being a value.
- */
-class Expression extends Statement { }
-
 /**
  * A composite action
  */
-class CompositeActionStmt extends Statement instanceof Actions::CompositeAction {
-  RunsStmt getRunsStmt() { result = super.getRuns() }
+class CompositeAction extends AstNode instanceof Actions::CompositeAction {
+  Runs getRuns() { result = super.getRuns() }
 
-  InputsStmt getInputsStmt() { result = this.(YamlMapping).lookup("inputs") }
+  Inputs getInputs() { result = this.(YamlMapping).lookup("inputs") }
 
-  OutputsStmt getOutputsStmt() { result = this.(YamlMapping).lookup("outputs") }
+  Outputs getOutputs() { result = this.(YamlMapping).lookup("outputs") }
 }
 
-class RunsStmt extends Statement instanceof Actions::Runs {
-  StepStmt getAStepStmt() { result = super.getSteps().getElementNode(_) }
+class Runs extends AstNode instanceof Actions::Runs {
+  Step getAStep() { result = super.getSteps().getElementNode(_) }
 
-  StepStmt getStepStmt(int i) { result = super.getSteps().getElementNode(i) }
+  Step getStep(int i) { result = super.getSteps().getElementNode(i) }
 }
 
 /**
  * A Github Actions Workflow
  */
-class WorkflowStmt extends Statement instanceof Actions::Workflow {
+class Workflow extends AstNode instanceof Actions::Workflow {
   string getName() { result = super.getName() }
 
-  JobStmt getAJobStmt() { result = super.getJob(_) }
+  Job getAJob() { result = super.getJob(_) }
 
-  JobStmt getJobStmt(string id) { result = super.getJob(id) }
+  Job getJob(string id) { result = super.getJob(id) }
 
   predicate hasTriggerEvent(string trigger) {
     exists(YamlNode n | n = super.getOn().(YamlMappingLikeNode).getNode(trigger))
@@ -80,27 +71,25 @@ class WorkflowStmt extends Statement instanceof Actions::Workflow {
     exists(YamlNode n | n = super.getOn().(YamlMappingLikeNode).getNode(result))
   }
 
-  Statement getPermissionsStmt() { result = this.(YamlMapping).lookup("permissions") }
+  Permissions getPermissions() { result = this.(YamlMapping).lookup("permissions") }
 
-  StrategyStmt getStrategyStmt() { result = this.(YamlMapping).lookup("strategy") }
+  Strategy getStrategy() { result = this.(YamlMapping).lookup("strategy") }
 }
 
-class ReusableWorkflowStmt extends WorkflowStmt {
+class ReusableWorkflow extends Workflow {
   YamlValue workflow_call;
 
-  ReusableWorkflowStmt() {
-    this.(Actions::Workflow).getOn().getNode("workflow_call") = workflow_call
-  }
+  ReusableWorkflow() { this.(Actions::Workflow).getOn().getNode("workflow_call") = workflow_call }
 
-  InputsStmt getInputsStmt() { result = workflow_call.(YamlMapping).lookup("inputs") }
+  Inputs getInputs() { result = workflow_call.(YamlMapping).lookup("inputs") }
 
-  OutputsStmt getOutputsStmt() { result = workflow_call.(YamlMapping).lookup("outputs") }
+  Outputs getOutputs() { result = workflow_call.(YamlMapping).lookup("outputs") }
 }
 
-class InputsStmt extends Statement instanceof YamlMapping {
+class Inputs extends AstNode instanceof YamlMapping {
   YamlMapping parent;
 
-  InputsStmt() { parent.lookup("inputs") = this }
+  Inputs() { parent.lookup("inputs") = this }
 
   /**
    * Gets a specific input expression (YamlMapping) by name.
@@ -111,10 +100,10 @@ class InputsStmt extends Statement instanceof YamlMapping {
   }
 }
 
-class OutputsStmt extends Statement instanceof YamlMapping {
+class Outputs extends AstNode instanceof YamlMapping {
   YamlMapping parent;
 
-  OutputsStmt() { parent.lookup("outputs") = this }
+  Outputs() { parent.lookup("outputs") = this }
 
   /**
    * Gets a specific output expression (YamlMapping) by name.
@@ -127,10 +116,16 @@ class OutputsStmt extends Statement instanceof YamlMapping {
   string getAnOutputName() { this.(YamlMapping).maps(any(YamlString s | s.getValue() = result), _) }
 }
 
-class StrategyStmt extends Statement instanceof YamlMapping {
+class Permissions extends AstNode instanceof YamlMapping {
   YamlMapping parent;
 
-  StrategyStmt() { parent.lookup("strategy") = this }
+  Permissions() { parent.lookup("permissions") = this }
+}
+
+class Strategy extends AstNode instanceof YamlMapping {
+  YamlMapping parent;
+
+  Strategy() { parent.lookup("strategy") = this }
 
   /**
    * Gets a specific matric expression (YamlMapping) by name.
@@ -144,31 +139,10 @@ class StrategyStmt extends Statement instanceof YamlMapping {
   }
 }
 
-class InputExpr extends Expression instanceof YamlString {
-  InputExpr() { exists(InputsStmt inputs | inputs.(YamlMapping).maps(this, _)) }
-}
-
-class OutputExpr extends Expression instanceof YamlString {
-  OutputExpr() {
-    exists(OutputsStmt outputs |
-      outputs.(YamlMapping).lookup(_).(YamlMapping).lookup("value") = this or
-      outputs.(YamlMapping).lookup(_) = this
-    )
-  }
-}
-
-class MatrixVariableExpr extends Expression instanceof YamlString {
-  MatrixVariableExpr() {
-    exists(StrategyStmt outputs |
-      outputs.(YamlMapping).lookup("matrix").(YamlMapping).lookup(_) = this
-    )
-  }
-}
-
 /**
  * A Job is a collection of steps that run in an execution environment.
  */
-class JobStmt extends Statement instanceof Actions::Job {
+class Job extends AstNode instanceof Actions::Job {
   /**
    * Gets the ID of this job, as a string.
    * This is the job's key within the `jobs` mapping.
@@ -176,20 +150,20 @@ class JobStmt extends Statement instanceof Actions::Job {
   string getId() { result = super.getId() }
 
   /** Gets the step at the given index within this job. */
-  StepStmt getStepStmt(int index) { result = super.getStep(index) }
+  Step getStep(int index) { result = super.getStep(index) }
 
   /** Gets any steps that are defined within this job. */
-  StepStmt getAStepStmt() { result = super.getStep(_) }
+  Step getAStep() { result = super.getStep(_) }
 
   /**
    * Gets a needed job.
    * eg:
    *     - needs: [job1, job2]
    */
-  JobStmt getNeededJob() {
+  Job getNeededJob() {
     exists(Actions::Needs needs |
       needs.getJob() = this and
-      result = needs.getANeededJob().(JobStmt)
+      result = needs.getANeededJob()
     )
   }
 
@@ -199,7 +173,7 @@ class JobStmt extends Statement instanceof Actions::Job {
    *   out1: ${steps.foo.bar}
    *   out2: ${steps.foo.baz}
    */
-  OutputsStmt getOutputsStmt() { result = this.(Actions::Job).lookup("outputs") }
+  Outputs getOutputs() { result = this.(Actions::Job).lookup("outputs") }
 
   /**
    * Reusable workflow jobs may have Uses children
@@ -209,42 +183,42 @@ class JobStmt extends Statement instanceof Actions::Job {
    *   with:
    *     arg1: value1
    */
-  JobUsesExpr getUsesExpr() { result.getJobStmt() = this }
+  JobUses getUses() { result.getJob() = this }
 
   predicate usesReusableWorkflow() {
     this.(YamlMapping).maps(any(YamlString s | s.getValue() = "uses"), _)
   }
 
-  IfStmt getIfStmt() { result = super.getIf() }
+  If getIf() { result = super.getIf() }
 
-  Statement getPermissionsStmt() { result = this.(YamlMapping).lookup("permissions") }
+  Permissions getPermissions() { result = this.(YamlMapping).lookup("permissions") }
 
-  StrategyStmt getStrategyStmt() { result = this.(YamlMapping).lookup("strategy") }
+  Strategy getStrategy() { result = this.(YamlMapping).lookup("strategy") }
 }
 
 /**
  * A Step is a single task that can be executed as part of a job.
  */
-class StepStmt extends Statement instanceof Actions::Step {
+class Step extends AstNode instanceof Actions::Step {
   string getId() { result = super.getId() }
 
-  JobStmt getJobStmt() { result = super.getJob() }
+  Job getJob() { result = super.getJob() }
 
-  IfStmt getIfStmt() { result = super.getIf() }
+  If getIf() { result = super.getIf() }
 }
 
 /**
  * An If node representing a conditional statement.
  */
-class IfStmt extends Statement {
+class If extends AstNode {
   YamlMapping parent;
 
-  IfStmt() {
+  If() {
     (parent instanceof Actions::Step or parent instanceof Actions::Job) and
     parent.lookup("if") = this
   }
 
-  Statement getEnclosingStatement() { result = parent }
+  AstNode getEnclosingNode() { result = parent }
 
   string getCondition() { result = this.(YamlScalar).getValue() }
 }
@@ -252,7 +226,7 @@ class IfStmt extends Statement {
 /**
  * Abstract class representing a call to a 3rd party action or reusable workflow.
  */
-abstract class UsesExpr extends Expression {
+abstract class Uses extends AstNode {
   abstract string getCallee();
 
   abstract string getVersion();
@@ -263,10 +237,10 @@ abstract class UsesExpr extends Expression {
 /**
  * A Uses step represents a call to an action that is defined in a GitHub repository.
  */
-class StepUsesExpr extends StepStmt, UsesExpr {
+class StepUses extends Step, Uses {
   Actions::Uses uses;
 
-  StepUsesExpr() { uses.getStep() = this }
+  StepUses() { uses.getStep() = this }
 
   override string getCallee() { result = uses.getGitHubRepository() }
 
@@ -288,12 +262,10 @@ class StepUsesExpr extends StepStmt, UsesExpr {
 /**
  * A Uses step represents a call to an action that is defined in a GitHub repository.
  */
-class JobUsesExpr extends UsesExpr instanceof YamlMapping {
-  JobUsesExpr() {
-    this instanceof JobStmt and this.maps(any(YamlString s | s.getValue() = "uses"), _)
-  }
+class JobUses extends Uses instanceof YamlMapping {
+  JobUses() { this instanceof Job and this.maps(any(YamlString s | s.getValue() = "uses"), _) }
 
-  JobStmt getJobStmt() { result = this }
+  Job getJob() { result = this }
 
   /**
    * Gets a regular expression that parses an `owner/repo@version` reference within a `uses` field in an Actions job step.
@@ -336,10 +308,10 @@ class JobUsesExpr extends UsesExpr instanceof YamlMapping {
 /**
  * A Run step represents the evaluation of a provided script
  */
-class RunExpr extends StepStmt, Expression {
+class Run extends Step {
   Actions::Run scriptExpr;
 
-  RunExpr() { scriptExpr.getStep() = this }
+  Run() { scriptExpr.getStep() = this }
 
   Expression getScriptExpr() { result = scriptExpr }
 
@@ -347,24 +319,59 @@ class RunExpr extends StepStmt, Expression {
 }
 
 /**
- * Evaluation of a workflow expression ${{}}.
+ * An AST node associated with a Reusable Workflow input.
  */
-class ExprAccessExpr extends Expression instanceof YamlString {
-  string expr;
-
-  ExprAccessExpr() { expr = Actions::getASimpleReferenceExpression(this) }
-
-  string getExpression() { result = expr }
-
-  JobStmt getJobStmt() { result.getAChildNode*() = this }
+class InputExpr extends AstNode {
+  InputExpr() { exists(Inputs inputs | inputs.(YamlMapping).maps(this, _)) }
 }
 
 /**
- * A context access expression.
+ * An AST node holding an Env var value.
+ */
+class EnvExpr extends AstNode {
+  EnvExpr() { exists(Actions::Env env | env.(YamlMapping).lookup(_) = this) }
+}
+
+/**
+ * An AST node holding a job or workflow output var.
+ */
+class OutputExpr extends AstNode {
+  OutputExpr() {
+    exists(Outputs outputs |
+      outputs.(YamlMapping).lookup(_).(YamlMapping).lookup("value") = this or
+      outputs.(YamlMapping).lookup(_) = this
+    )
+  }
+}
+
+/**
+ * An AST node holding a matrix var.
+ */
+class MatrixVariableExpr extends AstNode {
+  MatrixVariableExpr() {
+    exists(Strategy outputs | outputs.(YamlMapping).lookup("matrix").(YamlMapping).lookup(_) = this)
+  }
+}
+
+/**
+ * Evaluation of a workflow expression ${{}}.
+ */
+class Expression extends AstNode instanceof YamlString {
+  string expr;
+
+  Expression() { expr = Actions::getASimpleReferenceExpression(this) }
+
+  string getExpression() { result = expr }
+
+  Job getJob() { result.getAChildNode*() = this }
+}
+
+/**
+ * A ${{}} expression accessing a context variable.
  * https://docs.github.com/en/actions/learn-github-actions/contexts#context-availability
  */
-class CtxAccessExpr extends ExprAccessExpr {
-  CtxAccessExpr() {
+class ContextExpression extends Expression {
+  ContextExpression() {
     expr.regexpMatch([
         stepsCtxRegex(), needsCtxRegex(), jobsCtxRegex(), envCtxRegex(), inputsCtxRegex(),
         matrixCtxRegex()
@@ -373,7 +380,7 @@ class CtxAccessExpr extends ExprAccessExpr {
 
   abstract string getFieldName();
 
-  abstract Expression getRefExpr();
+  abstract AstNode getTarget();
 }
 
 private string stepsCtxRegex() {
@@ -406,11 +413,11 @@ private string wrapRegexp(string regex) {
  * https://docs.github.com/en/actions/learn-github-actions/contexts#context-availability
  * e.g. `${{ steps.changed-files.outputs.all_changed_files }}`
  */
-class StepsCtxAccessExpr extends CtxAccessExpr {
+class StepsExpression extends ContextExpression {
   string stepId;
   string fieldName;
 
-  StepsCtxAccessExpr() {
+  StepsExpression() {
     expr.regexpMatch(stepsCtxRegex()) and
     stepId = expr.regexpCapture(stepsCtxRegex(), 1) and
     fieldName = expr.regexpCapture(stepsCtxRegex(), 2)
@@ -418,9 +425,9 @@ class StepsCtxAccessExpr extends CtxAccessExpr {
 
   override string getFieldName() { result = fieldName }
 
-  override Expression getRefExpr() {
+  override AstNode getTarget() {
     this.getLocation().getFile() = result.getLocation().getFile() and
-    result.(StepStmt).getId() = stepId
+    result.(Step).getId() = stepId
   }
 }
 
@@ -429,12 +436,12 @@ class StepsCtxAccessExpr extends CtxAccessExpr {
  * https://docs.github.com/en/actions/learn-github-actions/contexts#context-availability
  * e.g. `${{ needs.job1.outputs.foo}}`
  */
-class NeedsCtxAccessExpr extends CtxAccessExpr {
-  JobStmt job;
+class NeedsExpression extends ContextExpression {
+  Job job;
   string jobId;
   string fieldName;
 
-  NeedsCtxAccessExpr() {
+  NeedsExpression() {
     expr.regexpMatch(needsCtxRegex()) and
     jobId = expr.regexpCapture(needsCtxRegex(), 1) and
     fieldName = expr.regexpCapture(needsCtxRegex(), 2) and
@@ -445,14 +452,14 @@ class NeedsCtxAccessExpr extends CtxAccessExpr {
 
   override string getFieldName() { result = fieldName }
 
-  override Expression getRefExpr() {
+  override AstNode getTarget() {
     job.getLocation().getFile() = this.getLocation().getFile() and
     (
       // regular jobs
-      job.getOutputsStmt() = result
+      job.getOutputs() = result
       or
       // reusable workflow calling jobs
-      job.getUsesExpr() = result
+      job.getUses() = result
     )
   }
 }
@@ -462,11 +469,11 @@ class NeedsCtxAccessExpr extends CtxAccessExpr {
  * https://docs.github.com/en/actions/learn-github-actions/contexts#context-availability
  * e.g. `${{ jobs.job1.outputs.foo}}` (within reusable workflows)
  */
-class JobsCtxAccessExpr extends CtxAccessExpr {
+class JobsExpression extends ContextExpression {
   string jobId;
   string fieldName;
 
-  JobsCtxAccessExpr() {
+  JobsExpression() {
     expr.regexpMatch(jobsCtxRegex()) and
     jobId = expr.regexpCapture(jobsCtxRegex(), 1) and
     fieldName = expr.regexpCapture(jobsCtxRegex(), 2)
@@ -474,11 +481,11 @@ class JobsCtxAccessExpr extends CtxAccessExpr {
 
   override string getFieldName() { result = fieldName }
 
-  override Expression getRefExpr() {
-    exists(JobStmt job |
+  override AstNode getTarget() {
+    exists(Job job |
       job.getId() = jobId and
       job.getLocation().getFile() = this.getLocation().getFile() and
-      job.getOutputsStmt() = result
+      job.getOutputs() = result
     )
   }
 }
@@ -488,21 +495,23 @@ class JobsCtxAccessExpr extends CtxAccessExpr {
  * https://docs.github.com/en/actions/learn-github-actions/contexts#context-availability
  * e.g. `${{ inputs.foo }}`
  */
-class InputsCtxAccessExpr extends CtxAccessExpr {
+class InputsExpression extends ContextExpression {
   string fieldName;
 
-  InputsCtxAccessExpr() {
+  InputsExpression() {
     expr.regexpMatch(inputsCtxRegex()) and
     fieldName = expr.regexpCapture(inputsCtxRegex(), 1)
   }
 
   override string getFieldName() { result = fieldName }
 
-  override Expression getRefExpr() {
+  override AstNode getTarget() {
     result.getLocation().getFile() = this.getLocation().getFile() and
-    exists(ReusableWorkflowStmt w | w.getInputsStmt().getInputExpr(fieldName) = result)
-    or
-    exists(CompositeActionStmt a | a.getInputsStmt().getInputExpr(fieldName) = result)
+    (
+      exists(ReusableWorkflow w | w.getInputs().getInputExpr(fieldName) = result)
+      or
+      exists(CompositeAction a | a.getInputs().getInputExpr(fieldName) = result)
+    )
   }
 }
 
@@ -511,18 +520,18 @@ class InputsCtxAccessExpr extends CtxAccessExpr {
  * https://docs.github.com/en/actions/learn-github-actions/contexts#context-availability
  * e.g. `${{ env.foo }}`
  */
-class EnvCtxAccessExpr extends CtxAccessExpr {
+class EnvExpression extends ContextExpression {
   string fieldName;
 
-  EnvCtxAccessExpr() {
+  EnvExpression() {
     expr.regexpMatch(envCtxRegex()) and
     fieldName = expr.regexpCapture(envCtxRegex(), 1)
   }
 
   override string getFieldName() { result = fieldName }
 
-  override Expression getRefExpr() {
-    exists(Statement s |
+  override AstNode getTarget() {
+    exists(AstNode s |
       s.getEnvExpr(fieldName) = result and
       s.getAChildNode*() = this
     )
@@ -534,24 +543,24 @@ class EnvCtxAccessExpr extends CtxAccessExpr {
  * https://docs.github.com/en/actions/learn-github-actions/contexts#context-availability
  * e.g. `${{ matrix.foo }}`
  */
-class MatrixCtxAccessExpr extends CtxAccessExpr {
+class MatrixExpression extends ContextExpression {
   string fieldName;
 
-  MatrixCtxAccessExpr() {
+  MatrixExpression() {
     expr.regexpMatch(matrixCtxRegex()) and
     fieldName = expr.regexpCapture(matrixCtxRegex(), 1)
   }
 
   override string getFieldName() { result = fieldName }
 
-  override Expression getRefExpr() {
-    exists(WorkflowStmt w |
-      w.getStrategyStmt().getMatrixVariableExpr(fieldName) = result and
+  override AstNode getTarget() {
+    exists(Workflow w |
+      w.getStrategy().getMatrixVariableExpr(fieldName) = result and
       w.getAChildNode*() = this
     )
     or
-    exists(JobStmt j |
-      j.getStrategyStmt().getMatrixVariableExpr(fieldName) = result and
+    exists(Job j |
+      j.getStrategy().getMatrixVariableExpr(fieldName) = result and
       j.getAChildNode*() = this
     )
   }
diff --git a/ql/lib/codeql/actions/controlflow/BasicBlocks.qll b/ql/lib/codeql/actions/controlflow/BasicBlocks.qll
index cdc7b0cf24f..af5e0f62552 100644
--- a/ql/lib/codeql/actions/controlflow/BasicBlocks.qll
+++ b/ql/lib/codeql/actions/controlflow/BasicBlocks.qll
@@ -442,4 +442,3 @@ class ConditionBlock extends BasicBlock {
    */
   predicate controls(BasicBlock controlled, BooleanSuccessor s) { controls(this, controlled, s) }
 }
-
diff --git a/ql/lib/codeql/actions/controlflow/internal/Cfg.qll b/ql/lib/codeql/actions/controlflow/internal/Cfg.qll
index b8137172b8c..2bc86723493 100644
--- a/ql/lib/codeql/actions/controlflow/internal/Cfg.qll
+++ b/ql/lib/codeql/actions/controlflow/internal/Cfg.qll
@@ -83,9 +83,9 @@ module Completion {
 module CfgScope {
   abstract class CfgScope extends AstNode { }
 
-  class WorkflowScope extends CfgScope instanceof WorkflowStmt { }
+  class WorkflowScope extends CfgScope instanceof Workflow { }
 
-  class CompositeActionScope extends CfgScope instanceof CompositeActionStmt { }
+  class CompositeActionScope extends CfgScope instanceof CompositeAction { }
 }
 
 private module Implementation implements CfgShared::InputSig<Location> {
@@ -119,13 +119,13 @@ private module Implementation implements CfgShared::InputSig<Location> {
   int maxSplits() { result = 0 }
 
   predicate scopeFirst(CfgScope scope, AstNode e) {
-    first(scope.(WorkflowStmt), e) or
-    first(scope.(CompositeActionStmt), e)
+    first(scope.(Workflow), e) or
+    first(scope.(CompositeAction), e)
   }
 
   predicate scopeLast(CfgScope scope, AstNode e, Completion c) {
-    last(scope.(WorkflowStmt), e, c) or
-    last(scope.(CompositeActionStmt), e, c)
+    last(scope.(Workflow), e, c) or
+    last(scope.(CompositeAction), e, c)
   }
 
   predicate successorTypeIsSimple(SuccessorType t) { t instanceof NormalSuccessor }
@@ -143,14 +143,14 @@ private import CfgImpl
 private import Completion
 private import CfgScope
 
-private class CompositeActionTree extends StandardPreOrderTree instanceof CompositeActionStmt {
+private class CompositeActionTree extends StandardPreOrderTree instanceof CompositeAction {
   override ControlFlowTree getChildNode(int i) {
     result =
-      rank[i](Expression child, Location l |
+      rank[i](AstNode child, Location l |
         (
-          child = this.(CompositeActionStmt).getInputsStmt() or
-          child = this.(CompositeActionStmt).getOutputsStmt() or
-          child = this.(CompositeActionStmt).getRunsStmt()
+          child = this.(CompositeAction).getInputs() or
+          child = this.(CompositeAction).getOutputs() or
+          child = this.(CompositeAction).getRuns()
         ) and
         l = child.getLocation()
       |
@@ -161,21 +161,21 @@ private class CompositeActionTree extends StandardPreOrderTree instanceof Compos
   }
 }
 
-private class RunsTree extends StandardPreOrderTree instanceof RunsStmt {
-  override ControlFlowTree getChildNode(int i) { result = super.getStepStmt(i) }
+private class RunsTree extends StandardPreOrderTree instanceof Runs {
+  override ControlFlowTree getChildNode(int i) { result = super.getStep(i) }
 }
 
-private class WorkflowTree extends StandardPreOrderTree instanceof WorkflowStmt {
+private class WorkflowTree extends StandardPreOrderTree instanceof Workflow {
   override ControlFlowTree getChildNode(int i) {
-    if this instanceof ReusableWorkflowStmt
+    if this instanceof ReusableWorkflow
     then
       result =
-        rank[i](Expression child, Location l |
+        rank[i](AstNode child, Location l |
           (
-            child = this.(ReusableWorkflowStmt).getInputsStmt() or
-            child = this.(ReusableWorkflowStmt).getOutputsStmt() or
-            child = this.(ReusableWorkflowStmt).getStrategyStmt() or
-            child = this.(ReusableWorkflowStmt).getAJobStmt()
+            child = this.(ReusableWorkflow).getInputs() or
+            child = this.(ReusableWorkflow).getOutputs() or
+            child = this.(ReusableWorkflow).getStrategy() or
+            child = this.(ReusableWorkflow).getAJob()
           ) and
           l = child.getLocation()
         |
@@ -185,10 +185,10 @@ private class WorkflowTree extends StandardPreOrderTree instanceof WorkflowStmt
         )
     else
       result =
-        rank[i](Expression child, Location l |
+        rank[i](AstNode child, Location l |
           (
-            child = super.getAJobStmt() or
-            child = super.getStrategyStmt()
+            child = super.getAJob() or
+            child = super.getStrategy()
           ) and
           l = child.getLocation()
         |
@@ -199,10 +199,10 @@ private class WorkflowTree extends StandardPreOrderTree instanceof WorkflowStmt
   }
 }
 
-private class InputsTree extends StandardPreOrderTree instanceof InputsStmt {
+private class InputsTree extends StandardPreOrderTree instanceof Inputs {
   override ControlFlowTree getChildNode(int i) {
     result =
-      rank[i](Expression child, Location l |
+      rank[i](AstNode child, Location l |
         child = super.getInputExpr(_) and l = child.getLocation()
       |
         child
@@ -212,12 +212,10 @@ private class InputsTree extends StandardPreOrderTree instanceof InputsStmt {
   }
 }
 
-private class InputExprTree extends LeafTree instanceof InputExpr { }
-
-private class OutputsTree extends StandardPreOrderTree instanceof OutputsStmt {
+private class OutputsTree extends StandardPreOrderTree instanceof Outputs {
   override ControlFlowTree getChildNode(int i) {
     result =
-      rank[i](Expression child, Location l |
+      rank[i](AstNode child, Location l |
         child = super.getOutputExpr(_) and l = child.getLocation()
       |
         child
@@ -227,12 +225,10 @@ private class OutputsTree extends StandardPreOrderTree instanceof OutputsStmt {
   }
 }
 
-private class OutputExprTree extends LeafTree instanceof OutputExpr { }
-
-private class StrategyTree extends StandardPreOrderTree instanceof StrategyStmt {
+private class StrategyTree extends StandardPreOrderTree instanceof Strategy {
   override ControlFlowTree getChildNode(int i) {
     result =
-      rank[i](Expression child, Location l |
+      rank[i](AstNode child, Location l |
         child = super.getMatrixVariableExpr(_) and l = child.getLocation()
       |
         child
@@ -242,17 +238,15 @@ private class StrategyTree extends StandardPreOrderTree instanceof StrategyStmt
   }
 }
 
-private class MatrixVariableExprTree extends LeafTree instanceof MatrixVariableExpr { }
-
-private class JobTree extends StandardPreOrderTree instanceof JobStmt {
+private class JobTree extends StandardPreOrderTree instanceof Job {
   override ControlFlowTree getChildNode(int i) {
     result =
-      rank[i](Expression child, Location l |
+      rank[i](AstNode child, Location l |
         (
-          child = super.getAStepStmt() or
-          child = super.getOutputsStmt() or
-          child = super.getStrategyStmt() or
-          child = super.getUsesExpr()
+          child = super.getAStep() or
+          child = super.getOutputs() or
+          child = super.getStrategy() or
+          child = super.getUses()
         ) and
         l = child.getLocation()
       |
@@ -263,12 +257,10 @@ private class JobTree extends StandardPreOrderTree instanceof JobStmt {
   }
 }
 
-private class UsesExprTree extends LeafTree instanceof UsesExpr { }
-
-private class UsesTree extends StandardPreOrderTree instanceof UsesExpr {
+private class UsesTree extends StandardPreOrderTree instanceof Uses {
   override ControlFlowTree getChildNode(int i) {
     result =
-      rank[i](Expression child, Location l |
+      rank[i](AstNode child, Location l |
         (child = super.getArgumentExpr(_) or child = super.getEnvExpr(_)) and
         l = child.getLocation()
       |
@@ -279,11 +271,10 @@ private class UsesTree extends StandardPreOrderTree instanceof UsesExpr {
   }
 }
 
-private class RunTree extends StandardPreOrderTree instanceof RunExpr {
-  //override ControlFlowTree getChildNode(int i) { result = super.getScriptExpr() and i = 0 }
+private class RunTree extends StandardPreOrderTree instanceof Run {
   override ControlFlowTree getChildNode(int i) {
     result =
-      rank[i](Expression child, Location l |
+      rank[i](AstNode child, Location l |
         (child = super.getEnvExpr(_) or child = super.getScriptExpr()) and
         l = child.getLocation()
       |
@@ -294,4 +285,16 @@ private class RunTree extends StandardPreOrderTree instanceof RunExpr {
   }
 }
 
-private class ExprAccessTree extends LeafTree instanceof ExprAccessExpr { }
+private class UsesLeaf extends LeafTree instanceof Uses { }
+
+private class InputExprTree extends LeafTree instanceof InputExpr { }
+
+private class OutputExprTree extends LeafTree instanceof OutputExpr { }
+
+private class MatrixVariableExprTree extends LeafTree instanceof MatrixVariableExpr { }
+
+private class EnvExprTree extends LeafTree instanceof EnvExpr { }
+
+private class ExprAccessTree extends LeafTree instanceof ContextExpression { }
+
+private class AstNodeLeaf extends LeafTree instanceof Expression { }
diff --git a/ql/lib/codeql/actions/dataflow/ExternalFlow.qll b/ql/lib/codeql/actions/dataflow/ExternalFlow.qll
index 594b6017729..479078fe18b 100644
--- a/ql/lib/codeql/actions/dataflow/ExternalFlow.qll
+++ b/ql/lib/codeql/actions/dataflow/ExternalFlow.qll
@@ -42,7 +42,7 @@ predicate sinkModel(string action, string version, string input, string kind) {
 predicate externallyDefinedSource(
   DataFlow::Node source, string sourceType, string fieldName, string trigger
 ) {
-  exists(UsesExpr uses, string action, string version, string kind |
+  exists(Uses uses, string action, string version, string kind |
     sourceModel(action, version, fieldName, trigger, kind) and
     uses.getCallee() = action.toLowerCase() and
     (
@@ -65,7 +65,7 @@ predicate externallyDefinedSource(
 predicate externallyDefinedStoreStep(
   DataFlow::Node pred, DataFlow::Node succ, DataFlow::ContentSet c
 ) {
-  exists(UsesExpr uses, string action, string version, string input, string output |
+  exists(Uses uses, string action, string version, string input, string output |
     summaryModel(action, version, input, output, "taint") and
     c = any(DataFlow::FieldContent ct | ct.getName() = output.replaceAll("output.", "")) and
     uses.getCallee() = action.toLowerCase() and
@@ -87,7 +87,7 @@ predicate externallyDefinedStoreStep(
 }
 
 predicate externallyDefinedSink(DataFlow::ExprNode sink, string kind) {
-  exists(UsesExpr uses, string action, string version, string input |
+  exists(Uses uses, string action, string version, string input |
     (
       if input.trim().matches("env.%")
       then sink.asExpr() = uses.getEnvExpr(input.trim().replaceAll("env.", ""))
diff --git a/ql/lib/codeql/actions/dataflow/FlowSources.qll b/ql/lib/codeql/actions/dataflow/FlowSources.qll
index 0e82498bfc1..c30c963afdb 100644
--- a/ql/lib/codeql/actions/dataflow/FlowSources.qll
+++ b/ql/lib/codeql/actions/dataflow/FlowSources.qll
@@ -114,7 +114,7 @@ private class EventSource extends RemoteFlowSource {
   string trigger;
 
   EventSource() {
-    exists(ExprAccessExpr e, string context | this.asExpr() = e and context = e.getExpression() |
+    exists(Expression e, string context | this.asExpr() = e and context = e.getExpression() |
       trigger = ["issues", "issue_comment"] and isExternalUserControlledIssue(context)
       or
       trigger = ["pull_request_target", "pull_request_review", "pull_request_review_comment"] and
@@ -158,9 +158,9 @@ private class ExternallyDefinedSource extends RemoteFlowSource {
  * An input for a Composite Action
  */
 private class CompositeActionInputSource extends RemoteFlowSource {
-  CompositeActionStmt c;
+  CompositeAction c;
 
-  CompositeActionInputSource() { c.getInputsStmt().getInputExpr(_) = this.asExpr() }
+  CompositeActionInputSource() { c.getInputs().getInputExpr(_) = this.asExpr() }
 
   override string getSourceType() { result = "Composite action input" }
 
diff --git a/ql/lib/codeql/actions/dataflow/FlowSteps.qll b/ql/lib/codeql/actions/dataflow/FlowSteps.qll
index bc0c782e9ff..64df342ae9b 100644
--- a/ql/lib/codeql/actions/dataflow/FlowSteps.qll
+++ b/ql/lib/codeql/actions/dataflow/FlowSteps.qll
@@ -34,7 +34,7 @@ class AdditionalTaintStep extends Unit {
  *      echo "foo=$(echo $BODY)" >> "$GITHUB_OUTPUT"
  */
 predicate runEnvToScriptStoreStep(DataFlow::Node pred, DataFlow::Node succ, DataFlow::ContentSet c) {
-  exists(RunExpr r, string varName, string output |
+  exists(Run r, string varName, string output |
     c = any(DataFlow::FieldContent ct | ct.getName() = output.replaceAll("output\\.", "")) and
     r.getEnvExpr(varName) = pred.asExpr() and
     exists(string script, string line |
diff --git a/ql/lib/codeql/actions/dataflow/internal/DataFlowPrivate.qll b/ql/lib/codeql/actions/dataflow/internal/DataFlowPrivate.qll
index b9aafb8ec94..62975959b39 100644
--- a/ql/lib/codeql/actions/dataflow/internal/DataFlowPrivate.qll
+++ b/ql/lib/codeql/actions/dataflow/internal/DataFlowPrivate.qll
@@ -54,21 +54,22 @@ DataFlowType getNodeType(Node node) { any() }
 predicate nodeIsHidden(Node node) { none() }
 
 class DataFlowExpr extends Cfg::Node {
-  DataFlowExpr() { this.getAstNode() instanceof Expression }
+  DataFlowExpr() { any() }
+  //DataFlowExpr() { this.getAstNode() instanceof Expression }
 }
 
 /**
  * A call corresponds to a Uses steps where a 3rd party action or a reusable workflow get called
  */
 class DataFlowCall instanceof Cfg::Node {
-  DataFlowCall() { super.getAstNode() instanceof UsesExpr }
+  DataFlowCall() { super.getAstNode() instanceof Uses }
 
   /** Gets a textual representation of this element. */
   string toString() { result = super.toString() }
 
   Location getLocation() { result = super.getLocation() }
 
-  string getName() { result = super.getAstNode().(UsesExpr).getCallee() }
+  string getName() { result = super.getAstNode().(Uses).getCallee() }
 
   DataFlowCallable getEnclosingCallable() { result = super.getScope() }
 }
@@ -82,11 +83,11 @@ class DataFlowCallable instanceof Cfg::CfgScope {
   Location getLocation() { result = super.getLocation() }
 
   string getName() {
-    if this instanceof ReusableWorkflowStmt
-    then result = this.(ReusableWorkflowStmt).getLocation().getFile().getRelativePath()
+    if this instanceof ReusableWorkflow
+    then result = this.(ReusableWorkflow).getLocation().getFile().getRelativePath()
     else
-      if this instanceof CompositeActionStmt
-      then result = this.(CompositeActionStmt).getLocation().getFile().getRelativePath()
+      if this instanceof CompositeAction
+      then result = this.(CompositeAction).getLocation().getFile().getRelativePath()
       else none()
   }
 }
@@ -134,9 +135,9 @@ predicate typeStrongerThan(DataFlowType t1, DataFlowType t2) { none() }
 newtype TContent =
   TFieldContent(string name) {
     // We only use field flow for steps and jobs outputs, not for accessing other context fields such as env, matrix or inputs
-    name = any(StepsCtxAccessExpr a).getFieldName() or
-    name = any(NeedsCtxAccessExpr a).getFieldName() or
-    name = any(JobsCtxAccessExpr a).getFieldName()
+    name = any(StepsExpression a).getFieldName() or
+    name = any(NeedsExpression a).getFieldName() or
+    name = any(JobsExpression a).getFieldName()
   }
 
 predicate forceHighPrecision(Content c) { c instanceof FieldContent }
@@ -149,14 +150,14 @@ ContentApprox getContentApprox(Content c) { result = c }
  * Made a string to match the ArgumentPosition type.
  */
 class ParameterPosition extends string {
-  ParameterPosition() { exists(any(ReusableWorkflowStmt w).getInputsStmt().getInputExpr(this)) }
+  ParameterPosition() { exists(any(ReusableWorkflow w).getInputs().getInputExpr(this)) }
 }
 
 /**
  * Made a string to match `With:` keys in the AST
  */
 class ArgumentPosition extends string {
-  ArgumentPosition() { exists(any(UsesExpr e).getArgumentExpr(this)) }
+  ArgumentPosition() { exists(any(Uses e).getArgumentExpr(this)) }
 }
 
 /**
@@ -172,11 +173,11 @@ predicate parameterMatch(ParameterPosition ppos, ArgumentPosition apos) { ppos =
  * field name.
  */
 predicate stepsCtxLocalStep(Node nodeFrom, Node nodeTo) {
-  exists(UsesExpr astFrom, StepsCtxAccessExpr astTo |
+  exists(Uses astFrom, StepsExpression astTo |
     externallyDefinedSource(nodeFrom, _, "output." + astTo.getFieldName(), _) and
     astFrom = nodeFrom.asExpr() and
     astTo = nodeTo.asExpr() and
-    astTo.getRefExpr() = astFrom
+    astTo.getTarget() = astFrom
   )
 }
 
@@ -189,11 +190,11 @@ predicate stepsCtxLocalStep(Node nodeFrom, Node nodeTo) {
  * field name.
  */
 predicate needsCtxLocalStep(Node nodeFrom, Node nodeTo) {
-  exists(UsesExpr astFrom, NeedsCtxAccessExpr astTo |
+  exists(Uses astFrom, NeedsExpression astTo |
     externallyDefinedSource(nodeFrom, _, "output." + astTo.getFieldName(), _) and
     astFrom = nodeFrom.asExpr() and
     astTo = nodeTo.asExpr() and
-    astTo.getRefExpr() = astFrom
+    astTo.getTarget() = astFrom
   )
 }
 
@@ -202,10 +203,10 @@ predicate needsCtxLocalStep(Node nodeFrom, Node nodeTo) {
  * e.g. ${{ inputs.foo }}
  */
 predicate inputsCtxLocalStep(Node nodeFrom, Node nodeTo) {
-  exists(Expression astFrom, InputsCtxAccessExpr astTo |
+  exists(AstNode astFrom, InputsExpression astTo |
     astFrom = nodeFrom.asExpr() and
     astTo = nodeTo.asExpr() and
-    astTo.getRefExpr() = astFrom
+    astTo.getTarget() = astFrom
   )
 }
 
@@ -214,10 +215,10 @@ predicate inputsCtxLocalStep(Node nodeFrom, Node nodeTo) {
  * e.g. ${{ matrix.foo }}
  */
 predicate matrixCtxLocalStep(Node nodeFrom, Node nodeTo) {
-  exists(Expression astFrom, MatrixCtxAccessExpr astTo |
+  exists(AstNode astFrom, MatrixExpression astTo |
     astFrom = nodeFrom.asExpr() and
     astTo = nodeTo.asExpr() and
-    astTo.getRefExpr() = astFrom
+    astTo.getTarget() = astFrom
   )
 }
 
@@ -226,12 +227,12 @@ predicate matrixCtxLocalStep(Node nodeFrom, Node nodeTo) {
  * e.g. ${{ env.foo }}
  */
 predicate envCtxLocalStep(Node nodeFrom, Node nodeTo) {
-  exists(Expression astFrom, EnvCtxAccessExpr astTo |
+  exists(Expression astFrom, EnvExpression astTo |
     astFrom = nodeFrom.asExpr() and
     astTo = nodeTo.asExpr() and
     (
       externallyDefinedSource(nodeFrom, _, "env." + astTo.getFieldName(), _) or
-      astTo.getRefExpr() = astFrom
+      astTo.getTarget() = astFrom
     )
   )
 }
@@ -266,17 +267,17 @@ predicate simpleLocalFlowStep(Node nodeFrom, Node nodeTo) { localFlowStep(nodeFr
 predicate jumpStep(Node nodeFrom, Node nodeTo) { none() }
 
 /**
- * Holds if a CtxAccessExpr reads a field from a job (needs/jobs), step (steps) output via a read of `c` (fieldname)
+ * Holds if a Expression reads a field from a job (needs/jobs), step (steps) output via a read of `c` (fieldname)
  */
 predicate ctxFieldReadStep(Node node1, Node node2, ContentSet c) {
-  exists(CtxAccessExpr access |
+  exists(ContextExpression access |
     (
-      access instanceof NeedsCtxAccessExpr or
-      access instanceof StepsCtxAccessExpr or
-      access instanceof JobsCtxAccessExpr
+      access instanceof NeedsExpression or
+      access instanceof StepsExpression or
+      access instanceof JobsExpression
     ) and
     c = any(FieldContent ct | ct.getName() = access.getFieldName()) and
-    node1.asExpr() = access.getRefExpr() and
+    node1.asExpr() = access.getTarget() and
     node2.asExpr() = access
   )
 }
@@ -294,7 +295,7 @@ predicate readStep(Node node1, ContentSet c, Node node2) { ctxFieldReadStep(node
  * using the output variable name as the access path
  */
 predicate fieldStoreStep(Node node1, Node node2, ContentSet c) {
-  exists(OutputsStmt out, string fieldName |
+  exists(Outputs out, string fieldName |
     node1.asExpr() = out.getOutputExpr(fieldName) and
     node2.asExpr() = out and
     c = any(FieldContent ct | ct.getName() = fieldName)
diff --git a/ql/lib/codeql/actions/dataflow/internal/DataFlowPublic.qll b/ql/lib/codeql/actions/dataflow/internal/DataFlowPublic.qll
index 5fe3c741735..a8434cdb603 100644
--- a/ql/lib/codeql/actions/dataflow/internal/DataFlowPublic.qll
+++ b/ql/lib/codeql/actions/dataflow/internal/DataFlowPublic.qll
@@ -52,11 +52,11 @@ class ParameterNode extends ExprNode {
 
   ParameterNode() {
     this.asExpr() = input and
-    input = any(InputsStmt s).getInputExpr(_)
+    input = any(Inputs s).getInputExpr(_)
   }
 
   predicate isParameterOf(DataFlowCallable c, ParameterPosition pos) {
-    input = c.(ReusableWorkflowStmt).getInputsStmt().getInputExpr(pos)
+    input = c.(ReusableWorkflow).getInputs().getInputExpr(pos)
   }
 
   override string toString() { result = "input " + input.toString() }
@@ -81,12 +81,12 @@ class CallNode extends ExprNode {
  * An argument to a Uses step (call).
  */
 class ArgumentNode extends ExprNode {
-  ArgumentNode() { this.getCfgNode().getAstNode() = any(UsesExpr e).getArgumentExpr(_) }
+  ArgumentNode() { this.getCfgNode().getAstNode() = any(Uses e).getArgumentExpr(_) }
 
   predicate argumentOf(DataFlowCall call, ArgumentPosition pos) {
     this.getCfgNode() = call.(Cfg::Node).getASuccessor+() and
     call.(Cfg::Node).getAstNode() =
-      any(UsesExpr e | e.getArgumentExpr(pos) = this.getCfgNode().getAstNode())
+      any(Uses e | e.getArgumentExpr(pos) = this.getCfgNode().getAstNode())
   }
 }
 
@@ -94,11 +94,11 @@ class ArgumentNode extends ExprNode {
  * Reusable workflow output nodes
  */
 class ReturnNode extends ExprNode {
-  private OutputsStmt outputs;
+  private Outputs outputs;
 
   ReturnNode() {
     this.asExpr() = outputs and
-    outputs = any(ReusableWorkflowStmt s).getOutputsStmt()
+    outputs = any(ReusableWorkflow s).getOutputs()
   }
 
   ReturnKind getKind() { result = TNormalReturn() }
diff --git a/ql/src/Debug/partial.ql b/ql/src/Debug/partial.ql
index c0a694455dc..fbdf9ca7daa 100644
--- a/ql/src/Debug/partial.ql
+++ b/ql/src/Debug/partial.ql
@@ -15,7 +15,7 @@ import PartialFlow::PartialPathGraph
 private module MyConfig implements DataFlow::ConfigSig {
   predicate isSource(DataFlow::Node source) {
     source instanceof RemoteFlowSource and
-    source.getLocation().getFile().getBaseName() = "matrix.yml"
+    source.getLocation().getFile().getBaseName() = "argus_case_study.yml"
   }
 
   predicate isSink(DataFlow::Node sink) { none() }
diff --git a/ql/src/Security/CWE-020/CompositeActionsSinks.ql b/ql/src/Security/CWE-020/CompositeActionsSinks.ql
index 525307bcc28..5bff6abc7bb 100644
--- a/ql/src/Security/CWE-020/CompositeActionsSinks.ql
+++ b/ql/src/Security/CWE-020/CompositeActionsSinks.ql
@@ -18,14 +18,14 @@ import codeql.actions.dataflow.ExternalFlow
 
 private class ExpressionInjectionSink extends DataFlow::Node {
   ExpressionInjectionSink() {
-    exists(RunExpr e | e.getScriptExpr() = this.asExpr()) or
+    exists(Run e | e.getScriptExpr() = this.asExpr()) or
     externallyDefinedSink(this, "expression-injection")
   }
 }
 
 private module MyConfig implements DataFlow::ConfigSig {
   predicate isSource(DataFlow::Node source) {
-    exists(CompositeActionStmt c | c.getInputsStmt().getInputExpr(_) = source.asExpr())
+    exists(CompositeAction c | c.getInputs().getInputExpr(_) = source.asExpr())
   }
 
   predicate isSink(DataFlow::Node sink) { sink instanceof ExpressionInjectionSink }
diff --git a/ql/src/Security/CWE-020/CompositeActionsSources.ql b/ql/src/Security/CWE-020/CompositeActionsSources.ql
index b3eb6d348a8..12703a6cff2 100644
--- a/ql/src/Security/CWE-020/CompositeActionsSources.ql
+++ b/ql/src/Security/CWE-020/CompositeActionsSources.ql
@@ -20,11 +20,11 @@ private module MyConfig implements DataFlow::ConfigSig {
   predicate isSource(DataFlow::Node source) {
     source instanceof RemoteFlowSource and
     not source instanceof DataFlow::ParameterNode and
-    exists(CompositeActionStmt c | c.getAChildNode*() = source.asExpr())
+    exists(CompositeAction c | c.getAChildNode*() = source.asExpr())
   }
 
   predicate isSink(DataFlow::Node sink) {
-    exists(CompositeActionStmt c | c.getOutputsStmt().getOutputExpr(_) = sink.asExpr())
+    exists(CompositeAction c | c.getOutputs().getOutputExpr(_) = sink.asExpr())
   }
 
   predicate allowImplicitRead(DataFlow::Node node, DataFlow::ContentSet set) {
diff --git a/ql/src/Security/CWE-020/CompositeActionsSummaries.ql b/ql/src/Security/CWE-020/CompositeActionsSummaries.ql
index b451d9d1bda..e5933a73b36 100644
--- a/ql/src/Security/CWE-020/CompositeActionsSummaries.ql
+++ b/ql/src/Security/CWE-020/CompositeActionsSummaries.ql
@@ -18,11 +18,11 @@ import codeql.actions.dataflow.ExternalFlow
 
 private module MyConfig implements DataFlow::ConfigSig {
   predicate isSource(DataFlow::Node source) {
-    exists(CompositeActionStmt c | c.getInputsStmt().getInputExpr(_) = source.asExpr())
+    exists(CompositeAction c | c.getInputs().getInputExpr(_) = source.asExpr())
   }
 
   predicate isSink(DataFlow::Node sink) {
-    exists(CompositeActionStmt c | c.getOutputsStmt().getOutputExpr(_) = sink.asExpr())
+    exists(CompositeAction c | c.getOutputs().getOutputExpr(_) = sink.asExpr())
   }
 }
 
diff --git a/ql/src/Security/CWE-020/ReusableWorkflowsSinks.ql b/ql/src/Security/CWE-020/ReusableWorkflowsSinks.ql
index 9317b900158..1e1f942b200 100644
--- a/ql/src/Security/CWE-020/ReusableWorkflowsSinks.ql
+++ b/ql/src/Security/CWE-020/ReusableWorkflowsSinks.ql
@@ -18,14 +18,14 @@ import codeql.actions.dataflow.ExternalFlow
 
 private class ExpressionInjectionSink extends DataFlow::Node {
   ExpressionInjectionSink() {
-    exists(RunExpr e | e.getScriptExpr() = this.asExpr()) or
+    exists(Run e | e.getScriptExpr() = this.asExpr()) or
     externallyDefinedSink(this, "expression-injection")
   }
 }
 
 private module MyConfig implements DataFlow::ConfigSig {
   predicate isSource(DataFlow::Node source) {
-    exists(ReusableWorkflowStmt w | w.getInputsStmt().getInputExpr(_) = source.asExpr())
+    exists(ReusableWorkflow w | w.getInputs().getInputExpr(_) = source.asExpr())
   }
 
   predicate isSink(DataFlow::Node sink) { sink instanceof ExpressionInjectionSink }
diff --git a/ql/src/Security/CWE-020/ReusableWorkflowsSources.ql b/ql/src/Security/CWE-020/ReusableWorkflowsSources.ql
index eeea688b273..7bcea3d45b0 100644
--- a/ql/src/Security/CWE-020/ReusableWorkflowsSources.ql
+++ b/ql/src/Security/CWE-020/ReusableWorkflowsSources.ql
@@ -20,11 +20,11 @@ private module MyConfig implements DataFlow::ConfigSig {
   predicate isSource(DataFlow::Node source) {
     source instanceof RemoteFlowSource and
     not source instanceof DataFlow::ParameterNode and
-    exists(ReusableWorkflowStmt w | w.getAChildNode*() = source.asExpr())
+    exists(ReusableWorkflow w | w.getAChildNode*() = source.asExpr())
   }
 
   predicate isSink(DataFlow::Node sink) {
-    exists(ReusableWorkflowStmt w | w.getOutputsStmt().getOutputExpr(_) = sink.asExpr())
+    exists(ReusableWorkflow w | w.getOutputs().getOutputExpr(_) = sink.asExpr())
   }
 
   predicate allowImplicitRead(DataFlow::Node node, DataFlow::ContentSet set) {
diff --git a/ql/src/Security/CWE-020/ReusableWorkflowsSummaries.ql b/ql/src/Security/CWE-020/ReusableWorkflowsSummaries.ql
index 3949488e129..5ac0c299929 100644
--- a/ql/src/Security/CWE-020/ReusableWorkflowsSummaries.ql
+++ b/ql/src/Security/CWE-020/ReusableWorkflowsSummaries.ql
@@ -18,11 +18,11 @@ import codeql.actions.dataflow.ExternalFlow
 
 private module MyConfig implements DataFlow::ConfigSig {
   predicate isSource(DataFlow::Node source) {
-    exists(ReusableWorkflowStmt w | w.getInputsStmt().getInputExpr(_) = source.asExpr())
+    exists(ReusableWorkflow w | w.getInputs().getInputExpr(_) = source.asExpr())
   }
 
   predicate isSink(DataFlow::Node sink) {
-    exists(ReusableWorkflowStmt w | w.getOutputsStmt().getOutputExpr(_) = sink.asExpr())
+    exists(ReusableWorkflow w | w.getOutputs().getOutputExpr(_) = sink.asExpr())
   }
 }
 
diff --git a/ql/src/Security/CWE-094/CriticalExpressionInjection.ql b/ql/src/Security/CWE-094/CriticalExpressionInjection.ql
index a6baf060c9d..63f1a7a9d3a 100644
--- a/ql/src/Security/CWE-094/CriticalExpressionInjection.ql
+++ b/ql/src/Security/CWE-094/CriticalExpressionInjection.ql
@@ -19,7 +19,7 @@ import codeql.actions.dataflow.ExternalFlow
 
 private class ExpressionInjectionSink extends DataFlow::Node {
   ExpressionInjectionSink() {
-    exists(RunExpr e | e.getScriptExpr() = this.asExpr()) or
+    exists(Run e | e.getScriptExpr() = this.asExpr()) or
     externallyDefinedSink(this, "expression-injection")
   }
 }
@@ -40,8 +40,7 @@ where
   source
       .getNode()
       .asExpr()
-      .(Statement)
-      .getEnclosingWorkflowStmt()
+      .getEnclosingWorkflow()
       .hasTriggerEvent(source.getNode().(RemoteFlowSource).getATriggerEvent())
 select sink.getNode(), source, sink,
   "Potential expression injection, which may be controlled by an external user."
diff --git a/ql/src/Security/CWE-094/ExpressionInjection.ql b/ql/src/Security/CWE-094/ExpressionInjection.ql
index c34fcb74bbc..b13bf88abe6 100644
--- a/ql/src/Security/CWE-094/ExpressionInjection.ql
+++ b/ql/src/Security/CWE-094/ExpressionInjection.ql
@@ -19,7 +19,7 @@ import codeql.actions.dataflow.ExternalFlow
 
 private class ExpressionInjectionSink extends DataFlow::Node {
   ExpressionInjectionSink() {
-    exists(RunExpr e | e.getScriptExpr() = this.asExpr()) or
+    exists(Run e | e.getScriptExpr() = this.asExpr()) or
     externallyDefinedSink(this, "expression-injection")
   }
 }
diff --git a/ql/src/Security/CWE-275/MissingActionsPermissions.ql b/ql/src/Security/CWE-275/MissingActionsPermissions.ql
index a4cecf18b78..9373bf808e3 100644
--- a/ql/src/Security/CWE-275/MissingActionsPermissions.ql
+++ b/ql/src/Security/CWE-275/MissingActionsPermissions.ql
@@ -13,11 +13,11 @@
 
 import actions
 
-from WorkflowStmt workflow, JobStmt job
+from Workflow workflow, Job job
 where
-  job = workflow.getAJobStmt() and
+  job = workflow.getAJob() and
   (
-    not exists(workflow.getPermissionsStmt()) and
-    not exists(job.getPermissionsStmt())
+    not exists(workflow.getPermissions()) and
+    not exists(job.getPermissions())
   )
 select job, "Actions Job or Workflow does not set permissions"
diff --git a/ql/src/Security/CWE-829/UnpinnedActionsTag.ql b/ql/src/Security/CWE-829/UnpinnedActionsTag.ql
index 3c951a4e0b0..34bcbd7b060 100644
--- a/ql/src/Security/CWE-829/UnpinnedActionsTag.ql
+++ b/ql/src/Security/CWE-829/UnpinnedActionsTag.ql
@@ -21,10 +21,10 @@ private predicate isTrustedOrg(string repo) {
   exists(string org | org in ["actions", "github", "advanced-security"] | repo.matches(org + "/%"))
 }
 
-from StepUsesExpr uses, string repo, string version, WorkflowStmt workflow, string name
+from StepUses uses, string repo, string version, Workflow workflow, string name
 where
   uses.getCallee() = repo and
-  uses.getEnclosingWorkflowStmt() = workflow and
+  uses.getEnclosingWorkflow() = workflow and
   (
     workflow.getName() = name
     or
diff --git a/ql/src/Security/CWE-829/UntrustedCheckout.ql b/ql/src/Security/CWE-829/UntrustedCheckout.ql
index 3c745b5d84a..ed96d5f07c1 100644
--- a/ql/src/Security/CWE-829/UntrustedCheckout.ql
+++ b/ql/src/Security/CWE-829/UntrustedCheckout.ql
@@ -18,34 +18,34 @@ import actions
 /**
  * An If node that contains an `actor` check
  */
-class ActorCheckStmt extends IfStmt {
-  ActorCheckStmt() { this.getCondition().regexpMatch(".*github\\.(triggering_)?actor.*") }
+class ActorCheck extends If {
+  ActorCheck() { this.getCondition().regexpMatch(".*github\\.(triggering_)?actor.*") }
 }
 
 /**
  * An If node that contains a `label` check
  */
-class LabelCheckStmt extends IfStmt {
-  LabelCheckStmt() {
+class LabelCheck extends If {
+  LabelCheck() {
     this.getCondition().regexpMatch(".*github\\.event\\.pull_request\\.labels.*") or
     this.getCondition().regexpMatch(".*github\\.event\\.label\\.name.*")
   }
 }
 
-from WorkflowStmt w, JobStmt job, StepUsesExpr checkoutStep
+from Workflow w, Job job, StepUses checkoutStep
 where
   w.hasTriggerEvent("pull_request_target") and
-  w.getAJobStmt() = job and
-  job.getAStepStmt() = checkoutStep and
+  w.getAJob() = job and
+  job.getAStep() = checkoutStep and
   checkoutStep.getCallee() = "actions/checkout" and
   checkoutStep
       .getArgumentExpr("ref")
-      .(ExprAccessExpr)
+      .(Expression)
       .getExpression()
       .matches([
           "%github.event.pull_request.head.ref%", "%github.event.pull_request.head.sha%",
           "%github.event.pull_request.number%", "%github.event.number%", "%github.head_ref%"
         ]) and
-  not exists(ActorCheckStmt check | job.getIfStmt() = check or checkoutStep.getIfStmt() = check) and
-  not exists(LabelCheckStmt check | job.getIfStmt() = check or checkoutStep.getIfStmt() = check)
+  not exists(ActorCheck check | job.getIf() = check or checkoutStep.getIf() = check) and
+  not exists(LabelCheck check | job.getIf() = check or checkoutStep.getIf() = check)
 select checkoutStep, "Potential unsafe checkout of untrusted pull request on 'pull_request_target'."
diff --git a/ql/test/library-tests/test.expected b/ql/test/library-tests/test.expected
index 4007e6454ea..ffbbed2bac1 100644
--- a/ql/test/library-tests/test.expected
+++ b/ql/test/library-tests/test.expected
@@ -90,18 +90,11 @@ stepUsesNodes
 | .github/workflows/test.yml:19:9:26:6 | name: R ... d files |
 jobUsesNodes
 usesSteps
-| .github/workflows/test.yml:11:9:15:6 | uses: a ... kout@v4 | fetch-depth | .github/workflows/test.yml:13:24:13:24 | 0 |
-| .github/workflows/test.yml:19:9:26:6 | name: R ... d files | find | .github/workflows/test.yml:24:17:24:21 | "foo" |
-| .github/workflows/test.yml:19:9:26:6 | name: R ... d files | replace | .github/workflows/test.yml:25:20:25:21 | "" |
 | .github/workflows/test.yml:19:9:26:6 | name: R ... d files | source | .github/workflows/test.yml:23:19:23:63 | ${{ ste ... iles }} |
-runSteps1
+runSteps
 | .github/workflows/test.yml:26:9:28:6 | id: simplesink1 | echo ${{ steps.source.outputs.all_changed_files }} |
 | .github/workflows/test.yml:28:9:31:2 | id: simplesink2 | ${{ github.event.pull_request.head.ref }} |
 | .github/workflows/test.yml:39:9:40:53 | id: sink | echo ${{needs.job1.outputs.job_output}} |
-runSteps2
-| .github/workflows/test.yml:26:9:28:6 | id: simplesink1 | .github/workflows/test.yml:27:14:27:63 | echo ${ ... iles }} |
-| .github/workflows/test.yml:28:9:31:2 | id: simplesink2 | .github/workflows/test.yml:29:14:29:54 | ${{ git ... .ref }} |
-| .github/workflows/test.yml:39:9:40:53 | id: sink | .github/workflows/test.yml:40:14:40:52 | echo ${ ... utput}} |
 runStepChildren
 | .github/workflows/test.yml:26:9:28:6 | id: simplesink1 | .github/workflows/test.yml:26:9:26:10 | id |
 | .github/workflows/test.yml:26:9:28:6 | id: simplesink1 | .github/workflows/test.yml:26:13:26:23 | simplesink1 |
@@ -115,21 +108,6 @@ runStepChildren
 | .github/workflows/test.yml:39:9:40:53 | id: sink | .github/workflows/test.yml:39:13:39:16 | sink |
 | .github/workflows/test.yml:39:9:40:53 | id: sink | .github/workflows/test.yml:40:9:40:11 | run |
 | .github/workflows/test.yml:39:9:40:53 | id: sink | .github/workflows/test.yml:40:14:40:52 | echo ${ ... utput}} |
-varAccesses
-| .github/workflows/test.yml:8:19:8:49 | ${{ ste ... alue }} | steps.step.outputs.value |
-| .github/workflows/test.yml:23:19:23:63 | ${{ ste ... iles }} | steps.source.outputs.all_changed_files |
-| .github/workflows/test.yml:27:14:27:63 | echo ${ ... iles }} | steps.source.outputs.all_changed_files |
-| .github/workflows/test.yml:29:14:29:54 | ${{ git ... .ref }} | github.event.pull_request.head.ref |
-| .github/workflows/test.yml:34:9:34:23 | ${{ always() }} | always() |
-| .github/workflows/test.yml:40:14:40:52 | echo ${ ... utput}} | needs.job1.outputs.job_output |
-orphanVarAccesses
-nonOrphanVarAccesses
-| .github/workflows/test.yml:8:19:8:49 | ${{ ste ... alue }} | steps.step.outputs.value | .github/workflows/test.yml:8:7:10:4 | job_out ... alue }} |
-| .github/workflows/test.yml:23:19:23:63 | ${{ ste ... iles }} | steps.source.outputs.all_changed_files | .github/workflows/test.yml:23:11:26:6 | source: ... iles }} |
-| .github/workflows/test.yml:27:14:27:63 | echo ${ ... iles }} | steps.source.outputs.all_changed_files | .github/workflows/test.yml:26:9:28:6 | id: simplesink1 |
-| .github/workflows/test.yml:29:14:29:54 | ${{ git ... .ref }} | github.event.pull_request.head.ref | .github/workflows/test.yml:28:9:31:2 | id: simplesink2 |
-| .github/workflows/test.yml:34:9:34:23 | ${{ always() }} | always() | .github/workflows/test.yml:32:5:40:53 | runs-on ... -latest |
-| .github/workflows/test.yml:40:14:40:52 | echo ${ ... utput}} | needs.job1.outputs.job_output | .github/workflows/test.yml:39:9:40:53 | id: sink |
 parentNodes
 | .github/workflows/test.yml:1:1:1:2 | on | .github/workflows/test.yml:1:1:40:53 | on: push |
 | .github/workflows/test.yml:1:5:1:8 | push | .github/workflows/test.yml:1:1:40:53 | on: push |
@@ -200,6 +178,8 @@ parentNodes
 | .github/workflows/test.yml:40:9:40:11 | run | .github/workflows/test.yml:39:9:40:53 | id: sink |
 | .github/workflows/test.yml:40:14:40:52 | echo ${ ... utput}} | .github/workflows/test.yml:39:9:40:53 | id: sink |
 cfgNodes
+dfNodes
+exprNodes
 | .github/workflows/test.yml:1:1:40:53 | enter on: push |
 | .github/workflows/test.yml:1:1:40:53 | exit on: push |
 | .github/workflows/test.yml:1:1:40:53 | exit on: push (normal) |
@@ -218,44 +198,15 @@ cfgNodes
 | .github/workflows/test.yml:32:5:40:53 | runs-on ... -latest |
 | .github/workflows/test.yml:39:9:40:53 | id: sink |
 | .github/workflows/test.yml:40:14:40:52 | echo ${ ... utput}} |
-dfNodes
-| .github/workflows/test.yml:1:1:40:53 | on: push |
-| .github/workflows/test.yml:5:5:31:2 | runs-on ... -latest |
-| .github/workflows/test.yml:8:7:10:4 | job_out ... alue }} |
-| .github/workflows/test.yml:8:19:8:49 | ${{ ste ... alue }} |
-| .github/workflows/test.yml:11:9:15:6 | uses: a ... kout@v4 |
-| .github/workflows/test.yml:15:9:19:6 | name: G ... d files |
-| .github/workflows/test.yml:19:9:26:6 | name: R ... d files |
-| .github/workflows/test.yml:23:19:23:63 | ${{ ste ... iles }} |
-| .github/workflows/test.yml:26:9:28:6 | id: simplesink1 |
-| .github/workflows/test.yml:27:14:27:63 | echo ${ ... iles }} |
-| .github/workflows/test.yml:28:9:31:2 | id: simplesink2 |
-| .github/workflows/test.yml:29:14:29:54 | ${{ git ... .ref }} |
-| .github/workflows/test.yml:32:5:40:53 | runs-on ... -latest |
-| .github/workflows/test.yml:39:9:40:53 | id: sink |
-| .github/workflows/test.yml:40:14:40:52 | echo ${ ... utput}} |
-exprNodes
-| .github/workflows/test.yml:1:1:40:53 | on: push |
-| .github/workflows/test.yml:5:5:31:2 | runs-on ... -latest |
-| .github/workflows/test.yml:8:7:10:4 | job_out ... alue }} |
-| .github/workflows/test.yml:8:19:8:49 | ${{ ste ... alue }} |
-| .github/workflows/test.yml:11:9:15:6 | uses: a ... kout@v4 |
-| .github/workflows/test.yml:15:9:19:6 | name: G ... d files |
-| .github/workflows/test.yml:19:9:26:6 | name: R ... d files |
-| .github/workflows/test.yml:23:19:23:63 | ${{ ste ... iles }} |
-| .github/workflows/test.yml:26:9:28:6 | id: simplesink1 |
-| .github/workflows/test.yml:27:14:27:63 | echo ${ ... iles }} |
-| .github/workflows/test.yml:28:9:31:2 | id: simplesink2 |
-| .github/workflows/test.yml:29:14:29:54 | ${{ git ... .ref }} |
-| .github/workflows/test.yml:32:5:40:53 | runs-on ... -latest |
-| .github/workflows/test.yml:39:9:40:53 | id: sink |
-| .github/workflows/test.yml:40:14:40:52 | echo ${ ... utput}} |
 argumentNodes
 | .github/workflows/test.yml:23:19:23:63 | ${{ ste ... iles }} |
 usesIds
 | .github/workflows/test.yml:15:9:19:6 | name: G ... d files | source |
 | .github/workflows/test.yml:19:9:26:6 | name: R ... d files | step |
 nodeLocations
+| .github/workflows/test.yml:1:1:40:53 | enter on: push | .github/workflows/test.yml:1:1:40:53 | .github/workflows/test.yml@1:1:40:53 |
+| .github/workflows/test.yml:1:1:40:53 | exit on: push | .github/workflows/test.yml:1:1:40:53 | .github/workflows/test.yml@1:1:40:53 |
+| .github/workflows/test.yml:1:1:40:53 | exit on: push (normal) | .github/workflows/test.yml:1:1:40:53 | .github/workflows/test.yml@1:1:40:53 |
 | .github/workflows/test.yml:1:1:40:53 | on: push | .github/workflows/test.yml:1:1:40:53 | .github/workflows/test.yml@1:1:40:53 |
 | .github/workflows/test.yml:5:5:31:2 | runs-on ... -latest | .github/workflows/test.yml:5:5:31:2 | .github/workflows/test.yml@5:5:31:2 |
 | .github/workflows/test.yml:8:7:10:4 | job_out ... alue }} | .github/workflows/test.yml:8:7:10:4 | .github/workflows/test.yml@8:7:10:4 |
diff --git a/ql/test/library-tests/test.ql b/ql/test/library-tests/test.ql
index 168987284c3..7524e31f050 100644
--- a/ql/test/library-tests/test.ql
+++ b/ql/test/library-tests/test.ql
@@ -9,49 +9,39 @@ query predicate files(File f) { any() }
 
 query predicate yamlNodes(YamlNode n) { any() }
 
-query predicate jobNodes(JobStmt s) { any() }
+query predicate jobNodes(Job s) { any() }
 
-query predicate stepNodes(StepStmt s) { any() }
+query predicate stepNodes(Step s) { any() }
 
-query predicate allUsesNodes(UsesExpr s) { any() }
+query predicate allUsesNodes(Uses s) { any() }
 
-query predicate stepUsesNodes(StepUsesExpr s) { any() }
+query predicate stepUsesNodes(StepUses s) { any() }
 
-query predicate jobUsesNodes(JobUsesExpr s) { any() }
+query predicate jobUsesNodes(JobUses s) { any() }
 
-query predicate usesSteps(UsesExpr call, string argname, Expression arg) {
+query predicate usesSteps(Uses call, string argname, Expression arg) {
   call.getArgumentExpr(argname) = arg
 }
 
-query predicate runSteps1(RunExpr run, string body) { run.getScript() = body }
+query predicate runSteps(Run run, string body) { run.getScript() = body }
 
-query predicate runSteps2(RunExpr run, Expression bodyExpr) { run.getScriptExpr() = bodyExpr }
-
-query predicate runStepChildren(RunExpr run, AstNode child) { child.getParentNode() = run }
-
-query predicate varAccesses(ExprAccessExpr ea, string expr) { expr = ea.getExpression() }
-
-query predicate orphanVarAccesses(ExprAccessExpr va, string var) {
-  var = va.getExpression() and
-  not exists(AstNode n | n = va.getParentNode())
-}
-
-query predicate nonOrphanVarAccesses(ExprAccessExpr va, string var, AstNode parent) {
-  var = va.getExpression() and
-  parent = va.getParentNode()
-}
+query predicate runStepChildren(Run run, AstNode child) { child.getParentNode() = run }
 
 query predicate parentNodes(AstNode child, AstNode parent) { child.getParentNode() = parent }
 
-query predicate cfgNodes(Cfg::Node n) { any() }
+query predicate cfgNodes(Cfg::Node n) {
+  n.getLocation().getFile().getBaseName() = "argus_case_study.yml"
+} //any() }
 
-query predicate dfNodes(DataFlow::Node e) { any() }
+query predicate dfNodes(DataFlow::Node e) {
+  e.getLocation().getFile().getBaseName() = "argus_case_study.yml"
+} //any() }
 
-query predicate exprNodes(DataFlow::ExprNode e) { any() }
+query predicate exprNodes(DataFlow::Node e) { any() }
 
 query predicate argumentNodes(DataFlow::ArgumentNode e) { any() }
 
-query predicate usesIds(StepUsesExpr s, string a) { s.getId() = a }
+query predicate usesIds(StepUses s, string a) { s.getId() = a }
 
 query predicate nodeLocations(DataFlow::Node n, Location l) { n.getLocation() = l }
 
@@ -67,4 +57,4 @@ query predicate summaries(string action, string version, string input, string ou
 
 query predicate calls(DataFlow::CallNode call, string callee) { callee = call.getCallee() }
 
-query predicate needs(DataFlow::ExprNode e) { e.asExpr() instanceof NeedsCtxAccessExpr }
+query predicate needs(DataFlow::Node e) { e.asExpr() instanceof NeedsExpression }