diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0d7de2646..4ec51fe05 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,12 @@
 We'll note all notable changes in this file, including bug fixes, enhancements, and all closed issues.
 Dates are in `YYYY-MM-DD` format and versions are in [semantic versioning](http://semver.org/) format.
 
+## 0.12.2 2024-10-5
+
+### Fixed
+
+-   Corrected debugger behavior in the presence of reused values.
+
 ## 0.12.1 2024-09-28
 
 ### Fixed
diff --git a/package.json b/package.json
index 3aa881eb7..e62e681d8 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "wordplay",
-    "version": "0.12.0",
+    "version": "0.12.2",
     "scripts": {
         "postinstall": "run-script-os",
         "postinstall:default": "svelte-kit sync && cp .env.template .env",
diff --git a/src/components/annotations/Annotations.svelte b/src/components/annotations/Annotations.svelte
index 40ed19f5f..9d94b895a 100644
--- a/src/components/annotations/Annotations.svelte
+++ b/src/components/annotations/Annotations.svelte
@@ -212,9 +212,7 @@
                               );
                 if (firstExpression) {
                     const value =
-                        evaluator.getLatestExpressionValueInEvaluation(
-                            firstExpression,
-                        );
+                        evaluator.getLatestExpressionValue(firstExpression);
                     if (value)
                         nodeView = document.querySelector(
                             `.value[data-id="${value.id}"]`,
diff --git a/src/components/editor/Editor.svelte b/src/components/editor/Editor.svelte
index d315de6a4..2961aa813 100644
--- a/src/components/editor/Editor.svelte
+++ b/src/components/editor/Editor.svelte
@@ -1163,7 +1163,7 @@
                 .map((expr) => {
                     return {
                         expression: expr,
-                        value: $evaluation.evaluator.getLatestExpressionValueInEvaluation(
+                        value: $evaluation.evaluator.getLatestExpressionValue(
                             expr,
                         ),
                     };
diff --git a/src/components/editor/NodeView.svelte b/src/components/editor/NodeView.svelte
index fb4600751..7afeea382 100644
--- a/src/components/editor/NodeView.svelte
+++ b/src/components/editor/NodeView.svelte
@@ -49,10 +49,7 @@
             node instanceof Expression &&
             !node.isEvaluationInvolved()
         )
-            value =
-                $evaluation.evaluator.getLatestExpressionValueInEvaluation(
-                    node,
-                );
+            value = $evaluation.evaluator.getLatestExpressionValue(node);
     }
 
     const blocks = isBlocks();
diff --git a/src/models/Project.ts b/src/models/Project.ts
index c939d9c2d..48958d31d 100644
--- a/src/models/Project.ts
+++ b/src/models/Project.ts
@@ -478,13 +478,14 @@ export default class Project {
     /** Return true if the given expression is in this project and depends only on contants. */
     isConstant(expression: Expression): boolean {
         let constant = this.constants.get(expression);
-        const context = this.getNodeContext(expression);
         // If we haven't visited this expression yet, compute it.
         if (constant === undefined) {
             // Mark this as not constant, assuming (and preventing) cycles.
             this.constants.set(expression, false);
+            // Compute whether the expression is constant.
+            const context = this.getNodeContext(expression);
             constant = expression.isConstant(context);
-            // Now actually compute whether it's constant.
+            // Cache the determination for later.
             this.constants.set(expression, constant);
         }
         return constant;
diff --git a/src/nodes/Expression.ts b/src/nodes/Expression.ts
index 7d223f316..04c149749 100644
--- a/src/nodes/Expression.ts
+++ b/src/nodes/Expression.ts
@@ -134,13 +134,14 @@ export default abstract class Expression extends Node {
         evaluator: Evaluator,
     ): Markup;
 
-    /** Utility function for getting an optional result   */
+    /** Utility function for getting an optional result  */
     getValueIfDefined(
         locales: Locales,
         context: Context,
         evaluator: Evaluator,
     ) {
-        const value = evaluator.peekValue();
+        const value =
+            evaluator.peekValue() ?? evaluator.getLatestExpressionValue(this);
         return value ? new ValueRef(value, locales, context) : undefined;
     }
 
diff --git a/src/runtime/Evaluator.ts b/src/runtime/Evaluator.ts
index 1dbdb68a6..d6c4a5a8b 100644
--- a/src/runtime/Evaluator.ts
+++ b/src/runtime/Evaluator.ts
@@ -710,7 +710,7 @@ export default class Evaluator {
         return this.getLatestSourceValue(this.project.getMain());
     }
 
-    /** Evaluate until we're done */
+    /** Prepare for evaluation, and finish if playing. */
     start(changedStreams?: StreamValue[], limit = true): void {
         // If we're not done, finish first, if we were interrupted before.
         if (!this.isDone()) this.finish();
@@ -718,7 +718,7 @@ export default class Evaluator {
         // First, initialize any stream dependencies
         // If there are changed streams, construct a set of affected expressions that need to be reevaluated.
         // We'll reuse previous values for anything not affected.
-        if (changedStreams && !this.isInPast()) {
+        if (changedStreams && changedStreams.length > 0) {
             this.#currentStreamDependencies = new Set();
             for (const stream of changedStreams) {
                 const dependencies = this.#streamDependencies.get(
@@ -1131,8 +1131,10 @@ export default class Evaluator {
         // Reset the project to the beginning of time (but preserve stream history, since that's stored in project).
         this.resetForEvaluation(true, broadcast);
 
-        // Start the evaluation fresh.
-        this.start();
+        console.log('Step back to', change);
+
+        // Start the evaluation fresh, using the changed streams if we found any.
+        this.start(change ? change.changes.map((c) => c.stream) : undefined);
 
         // Step until reaching the target step index.
         while (this.#stepIndex < destinationStep) {
diff --git a/src/runtime/Finish.ts b/src/runtime/Finish.ts
index 89a5d77af..2c06a0304 100644
--- a/src/runtime/Finish.ts
+++ b/src/runtime/Finish.ts
@@ -28,6 +28,8 @@ export function finish(evaluator: Evaluator, expr: Expression) {
     if (shouldSkip(evaluator, expr)) {
         const priorValue = evaluator.getLatestExpressionValue(expr);
         if (priorValue !== undefined) {
+            // Ask the evaluator to remember the value we computed.
+            // evaluator.rememberExpressionValue(expr, priorValue);
             // Evaluate any side effects
             return expr.evaluate(evaluator, priorValue);
         }
diff --git a/src/runtime/Start.ts b/src/runtime/Start.ts
index 3ba211df9..232cedfbc 100644
--- a/src/runtime/Start.ts
+++ b/src/runtime/Start.ts
@@ -36,6 +36,7 @@ export function start(evaluator: Evaluator, expr: Expression) {
         shouldSkip(evaluator, expr) &&
         evaluator.getLatestExpressionValue(expr)
     ) {
+        console.log('Skipping ' + expr.toWordplay());
         // Ask the evaluator to jump past this start's corresponding finish.
         evaluator.jumpPast(expr);
     }
@@ -46,7 +47,7 @@ export function start(evaluator: Evaluator, expr: Expression) {
 export function shouldSkip(evaluator: Evaluator, expr: Expression) {
     return (
         !expr.isInternal() &&
-        !evaluator.isInPast() &&
+        // !evaluator.isInPast() &&
         (evaluator.project.isConstant(expr) ||
             (evaluator.isReacting() &&
                 !evaluator.isEvaluatingReaction() &&