fix(debugger): show JVM values as {Type@id} summary and map entries as key -> value

The Variables view showed the Java debugger's text under its type: args = {String[]} String[0]@9, map = {HashMap} HashMap@10 size=1, and a map entry as 0 = {HashMap$Node} HashMap$Node@31 "a":"b". A JVM object now reads {String[0]@9} [] and {HashMap@10} size = 1, a map entry as "a" -> "b" without its index, and a String without its type. Inline values and the value tooltip use the same text (args: [], map: size = 1). Values from other debuggers keep their text and type.

src/features/debugger/__tests__/toolWindow.test.tsx

@@ -307,7 +307,7 @@ describe("variables the adapter computes after the stop", () => {
     expect(await screen.findByText("Collecting data…")).toBeTruthy();
     adapterData.library = "com.example.library.Library@1";
     act(() => handleDebugEvent(1, { kind: "invalidated", areas: ["variables"] }));
-    const value = await screen.findByText("com.example.library.Library@1");
+    const value = await screen.findByText("{Library@1}");
     expect(screen.queryByText("Collecting data…")).toBeNull();
     expect(value.closest("[role=treeitem]")?.querySelector("[class*=changed]")).toBeNull();
   });
@@ -348,7 +348,7 @@ describe("variables the adapter computes after the stop", () => {
     await screen.findByText("Collecting data…");
     adapterData.library = "Library@2";
     await act(() => setVariableValue({ container: 1, name: "count", evaluateName: "count" }, "4", session));
-    expect(await screen.findByText("Library@2")).toBeTruthy();
+    expect(await screen.findByText("{Library@2}")).toBeTruthy();
   });
 
   it("does nothing for an invalidation while the program runs", async () => {

src/features/debugger/__tests__/values.test.ts

@@ -1,7 +1,7 @@
 import { describe, expect, it } from "vitest";
 import { EditorSelection, EditorState } from "@codemirror/state";
 import { selectionExpression } from "../editor/valueTooltip";
-import { classifyValue, identifiersIn, inlineValue, sortVariables } from "../values";
+import { classifyValue, identifiersIn, inlineValue, shownValue, sortVariables } from "../values";
 import { inlineValuesFor } from "../editor/execution";
 import { frameLabel, groupFrames, isLibraryFrame } from "../frames";
 import type { StackFrame } from "@/platform/ipc";
@@ -150,3 +150,25 @@ describe("selectionExpression", () => {
     expect(selectionExpression(multi)).toBeNull();
   });
 });
+
+describe("shown values", () => {
+  it.each([
+    ["String[0]@9", "String[]", { label: "{String[0]@9}", text: "[]" }],
+    ["int[3]@12", "int[]", { label: "{int[3]@12}", text: "" }],
+    ["HashMap@10 size=1", "HashMap", { label: "{HashMap@10}", text: "size = 1" }],
+    ["ArrayList@15 size=0", "java.util.ArrayList", { label: "{ArrayList@15}", text: "size = 0" }],
+    ["Db@21", "Db", { label: "{Db@21}", text: "" }],
+    ["com.example.Library@1", "Library", { label: "{Library@1}", text: "" }],
+    ['HashMap$Node@31 "a":"b"', "HashMap$Node", { label: null, text: '"a" -> "b"', entry: true }],
+    ['HashMap$Node@32 "a:b":"c"', "HashMap$Node", { label: null, text: '"a:b" -> "c"', entry: true }],
+    ['TreeMap$Entry@33 1:"x"', "TreeMap$Entry", { label: null, text: '1 -> "x"', entry: true }],
+    ['"hello"', "String", { label: null, text: '"hello"' }],
+    ["42", "int", { label: "{int}", text: "42" }],
+    // Other debuggers' values keep their text and type.
+    ["Foo@1", "Bar", { label: "{Bar}", text: "Foo@1" }],
+    ["{'a': 1}", "dict", { label: "{dict}", text: "{'a': 1}" }],
+    ["0x1000", null, { label: null, text: "0x1000" }],
+  ])("%s {%s}", (value, type, shown) => {
+    expect(shownValue(value, type)).toEqual(shown);
+  });
+});

src/features/debugger/editor/execution.ts

@@ -10,7 +10,7 @@ import { showHint } from "@/editor/lsp/hint";
 import { activeSession, useExecutionPoint } from "../state";
 import { onWorkflowSettingsChange, workflowSettings } from "@/platform/workflowSettings";
 import { tx } from "@/platform/i18n";
-import { identifiersIn, inlineValue } from "../values";
+import { identifiersIn, inlineValue, shownValue } from "../values";
 import { valueHint } from "./valueTooltip";
 import styles from "./editor.module.css";
 
@@ -113,11 +113,13 @@ export function inlineValuesFor(
             evaluateName: id,
           })
         : raw;
+    const shown = shownValue(variable.value, variable.typeName);
+    const value = shown.text || shown.label || variable.value;
     parts.push({
       name: id,
-      text: `${id}: ${inlineValue(variable.value, 40)}`,
+      text: `${id}: ${inlineValue(value, 40)}`,
       variable,
-      truncated: variable.value.length > 40,
+      truncated: value.length > 40,
     });
     if (parts.length >= MAX_PER_LINE) break;
   }

src/features/debugger/editor/valueTooltip.ts

@@ -10,7 +10,7 @@ import { showHint } from "@/editor/lsp/hint";
 import { workflowSettings } from "@/platform/workflowSettings";
 import { navigationModifierHeld } from "@/platform/navigationModifier";
 import { activeSession, evaluate } from "../state";
-import { inlineValue } from "../values";
+import { inlineValue, shownValue } from "../values";
 import { tx } from "@/platform/i18n";
 import { iconMarkup, selectableText } from "@/ui";
 import { mountValueTree } from "../ui/ValueHintTree";
@@ -70,13 +70,19 @@ export function valueHint(
   const name = document.createElement("span");
   name.className = styles.valueName!;
   name.textContent = `${expression} = `;
-  dom.append(name, max === null ? value.value : inlineValue(value.value, max));
-  if (value.typeName) {
-    const type = document.createElement("span");
-    type.className = styles.valueType!;
-    type.textContent = `  {${value.typeName}}`;
-    dom.append(type);
-  }
+  const shown = shownValue(value.value, value.typeName);
+  // A JVM object's `{Type@id}` leads its value; other types follow it.
+  const leading = shown.label?.includes("@") ?? false;
+  const type = (text: string) => {
+    const span = document.createElement("span");
+    span.className = styles.valueType!;
+    span.textContent = text;
+    return span;
+  };
+  dom.append(name);
+  if (leading) dom.append(type(`${shown.label} `));
+  dom.append(max === null ? shown.text : inlineValue(shown.text, max));
+  if (shown.label && !leading) dom.append(type(`  ${shown.label}`));
   return { dom, destroy: () => tree?.unmount() };
 }
 

src/features/debugger/ui/VariablesView.tsx

@@ -11,7 +11,7 @@ import { addFieldWatchpoint } from "../breakpoints/special";
 import { methodAt } from "../breakpoints/symbols";
 import { activeSession, addWatch, removeWatch, revealFrame, sessionSupports, setVariableValue } from "../state";
 import { blurDebugView, focusDebugView } from "./focusedView";
-import { classifyValue, oneLine, sortVariables } from "../values";
+import { classifyValue, oneLine, shownValue, sortVariables } from "../values";
 import { valueText } from "../valueText";
 import { workflowSettings } from "@/platform/workflowSettings";
 import styles from "./VariablesView.module.css";
@@ -486,20 +486,25 @@ function VarRow({
       </span>
     );
   const kind = node.error ? null : classifyValue(node.value, node.typeName);
+  const shown = shownValue(node.value, node.typeName);
   return (
     <span className={styles.row}>
       <Icon name={nodeIcon(node)} size={16} className={styles.nodeIcon} />
-      <span className={clsx(styles.name, node.kind === "var" && styles.varName, changed && styles.changed)}>
-        {node.name}
-      </span>
-      <span className={styles.eq}>=</span>
+      {!shown.entry && (
+        <>
+          <span className={clsx(styles.name, node.kind === "var" && styles.varName, changed && styles.changed)}>
+            {node.name}
+          </span>
+          <span className={styles.eq}>=</span>
+        </>
+      )}
       {node.error ? (
         <span className={styles.error}>{oneLine(node.error)}</span>
       ) : (
         <>
-          {node.typeName && <span className={styles.type}>{`{${node.typeName}}`}</span>}
+          {shown.label && <span className={styles.type}>{shown.label}</span>}
           <span ref={valueRef} className={clsx(styles.value, kind && styles[kind])} title={node.value}>
-            {oneLine(node.value)}
+            {oneLine(shown.text)}
           </span>
           {overflow && (
             <button

src/features/debugger/values.ts

@@ -69,3 +69,35 @@ export function sortVariables<T extends { name: string }>(vars: readonly T[]): T
   if (vars.every((v) => INDEX.test(v.name))) return [...vars];
   return [...vars].sort((a, b) => a.name.localeCompare(b.name, undefined, { numeric: true, sensitivity: "base" }));
 }
+
+/** How a variable's type and value read in the Variables view: the braced label before the value, then the value. */
+export interface ShownValue {
+  label: string | null;
+  text: string;
+  /** A map entry: the row shows `key -> value` alone, without its index. */
+  entry?: true;
+}
+
+// `HashMap@10 size=1`, `String[0]@9`: a JVM object as the Java debugger writes it (type, then the object id).
+const JVM_OBJECT = /^([\w$.]+(?:\[\d*\])*)@(\d+)(?:\s+(.*))?$/s;
+// A map entry's key, at the start of `"a":"b"` or `1:"b"`.
+const ENTRY_KEY = /^("(?:[^"\\]|\\.)*"|[^:"]+?):(.*)$/s;
+
+/**
+ * JVM objects read as `{HashMap@10} size = 1` and a map entry as `"a" -> "b"`; strings show without
+ * a type. Values in other forms keep the adapter's text under `{type}`.
+ */
+export function shownValue(value: string, typeName: string | null | undefined): ShownValue {
+  const plain = { label: typeName ? `{${typeName}}` : null, text: value };
+  if (!typeName) return plain;
+  if (typeName === "String" && /^".*"$/s.test(value)) return { label: null, text: value };
+  const object = JVM_OBJECT.exec(value);
+  if (!object) return plain;
+  const [, head, id, rest = ""] = object;
+  const simple = (t: string) => t.replace(/\[\d*\]/g, "[]").replace(/^.*\./, "");
+  if (simple(head!) !== simple(typeName)) return plain;
+  const entry = /(?:^|\$)\w*(?:Entry|Node)$/.test(typeName) ? ENTRY_KEY.exec(rest) : null;
+  if (entry) return { label: null, text: `${entry[1]!.trim()} -> ${entry[2]!.trim()}`, entry: true };
+  const text = rest.replace(/\b(size|length)=(\d+)/g, "$1 = $2") || (/\[0\]/.test(head!) ? "[]" : "");
+  return { label: `{${head!.replace(/^.*\./, "")}@${id}}`, text };
+}