Launch configuration updates

CHANGELOG.md

@@ -4,6 +4,18 @@ All notable changes to the Simics Target Debug extension will be documented here
 
 ## [Unreleased]
 
+### Changed
+
+- In TCF Launch Configurations, the Start, Duplicate and Delete buttons
+  above the form, and the Add and Delete All buttons above the list, stay
+  visible when you scroll.
+
+### Fixed
+
+- The Start button in TCF Launch Configurations is no longer disabled while
+  any Simics Target Debug session runs, only for configurations that connect
+  to an agent (host and port) that already has a session.
+
 ## [0.5.0] - 2026-11-02
 
 Initial release.

src/launchSettings/editorProvider.ts

@@ -14,20 +14,22 @@ import {
     setValue,
 } from "./launchJson";
 import { SettingValue, StateMessage, WebviewMessage } from "./protocol";
-import { Field, fieldPath, launchFields, launchTemplate, valueAtPath } from "./schema";
+import { Field, agentAddress, fieldPath, launchFields, launchTemplate, valueAtPath } from "./schema";
 
 /** Must match "customEditors" in package.json. */
 export const LAUNCH_SETTINGS_VIEW_TYPE = "simics-target-debug.launchSettings";
 
 const NEW_LAUNCH_JSON = '{\n    "version": "0.2.0",\n    "configurations": []\n}\n';
 
 const tcfSessions = new Set<vscode.DebugSession>();
-/** Set from the form's start until VS Code has started the session or failed. */
-let starting = false;
+/** Agents started from the form, each kept until VS Code has started the session or failed. */
+const startingAgents: string[] = [];
 const debuggingChanged = new vscode.EventEmitter<void>();
 
-function isDebugging(): boolean {
-    return starting || tcfSessions.size > 0;
+/** Agents with a running or starting session, see agentAddress. */
+function busyAgents(): string[] {
+    const running = [...tcfSessions].map((s) => agentAddress(s.configuration));
+    return [...new Set([...running, ...startingAgents])];
 }
 
 /** The values of the fields stored in VS Code settings, see Field.setting. */
@@ -148,7 +150,7 @@ class LaunchSettingsEditorProvider implements vscode.CustomTextEditorProvider {
                 error: result.error,
                 select,
                 missingPaths: [],
-                debugging: isDebugging(),
+                busyAgents: busyAgents(),
                 settings: settingValues(this.fields, document.uri),
             };
             select = undefined;
@@ -249,17 +251,20 @@ class LaunchSettingsEditorProvider implements vscode.CustomTextEditorProvider {
                 return;
             }
             case "start": {
-                if (isDebugging()) {
+                const text = checkedText(document, message.index, message.name);
+                const config = readConfigurations(text).configurations?.find((c) => c.index === message.index);
+                if (!config) {
+                    return;
+                }
+                const agent = agentAddress(config.values);
+                if (busyAgents().includes(agent)) {
                     void vscode.window.showInformationMessage(
-                        "A Simics Target Debug session is already running. " + "Stop it before starting another one.",
+                        `A Simics Target Debug session to ${agent} is already running. ` +
+                            "Stop it before starting another one.",
                     );
                     return;
                 }
-                const text = checkedText(document, message.index, message.name);
-                const config = readConfigurations(text).configurations?.find((c) => c.index === message.index);
-                if (config) {
-                    startDebugging(document, config);
-                }
+                startDebugging(document, config);
                 return;
             }
             case "add": {
@@ -351,7 +356,8 @@ function startDebugging(document: vscode.TextDocument, config: LaunchConfigurati
         ...config.values,
         name: config.name,
     } as vscode.DebugConfiguration;
-    starting = true;
+    const agent = agentAddress(config.values);
+    startingAgents.push(agent);
     debuggingChanged.fire();
     Promise.resolve(vscode.debug.startDebugging(vscode.workspace.getWorkspaceFolder(document.uri), debugConfig))
         .catch((err: unknown) => {
@@ -360,7 +366,7 @@ function startDebugging(document: vscode.TextDocument, config: LaunchConfigurati
             );
         })
         .finally(() => {
-            starting = false;
+            startingAgents.splice(startingAgents.indexOf(agent), 1);
             debuggingChanged.fire();
         });
 }

src/launchSettings/protocol.ts

@@ -12,8 +12,8 @@ export interface StateMessage {
     select?: number;
     /** Host paths that do not exist, as "<configuration index>:<JsonPath joined by />". */
     missingPaths: string[];
-    /** A Simics Target Debug session runs or is starting, only one is allowed. */
-    debugging: boolean;
+    /** Agents (see agentAddress) a Simics Target Debug session runs on or is starting on. */
+    busyAgents: string[];
     /** Values of the fields stored in VS Code settings, by field key. */
     settings: Record<string, SettingValue>;
 }

src/launchSettings/schema.ts

@@ -183,6 +183,12 @@ export function fieldPath(f: Field): string[] {
     return f.path ?? [f.key];
 }
 
+/** host:port of the agent a configuration connects to, with the same defaults as the debug session. */
+export function agentAddress(values: Record<string, unknown>): string {
+    const { host, port } = values;
+    return `${String(host ?? "localhost")}:${String(port ?? 1534)}`;
+}
+
 /** The value at `path` in `values`, if there is one. */
 export function valueAtPath(values: unknown, path: readonly (string | number)[]): unknown {
     let v = values;

src/launchSettings/webview/launchSettings.css

@@ -42,8 +42,12 @@ body {
     border-right: 1px solid var(--vscode-panel-border, var(--vscode-widget-border, transparent));
 }
 
-/* Looks like the title of a VS Code view. */
+/* Looks like the title of a VS Code view. Sticky, so its buttons stay visible in a long list. */
 .list-header {
+    position: sticky;
+    top: 0;
+    z-index: 5;
+    background: var(--vscode-editor-background);
     display: flex;
     align-items: center;
     justify-content: space-between;
@@ -129,14 +133,26 @@ body {
 .details {
     overflow: auto;
     padding: 0 24px 24px;
+    /* Fields that get focus are scrolled into view below the sticky header. */
+    scroll-padding-top: 40px;
 }
 
+/*
+ * Sticky, so Start, Duplicate and Delete stay visible when the form is scrolled.
+ * Spans the side padding of .details too, so no field shows beside it.
+ * Below the drop-down lists (z-index 10), which may open over it.
+ */
 .details-header {
+    position: sticky;
+    top: 0;
+    z-index: 5;
+    background: var(--vscode-editor-background);
     display: flex;
     align-items: center;
     justify-content: flex-end;
     gap: 12px;
-    padding: 10px 14px 0;
+    margin: 0 -24px;
+    padding: 10px 38px 4px;
 }
 
 .actions {

src/launchSettings/webview/launchSettings.ts

@@ -1,6 +1,7 @@
 import type { LaunchConfiguration } from "../launchJson";
 import type { JsonPath, StateMessage, WebviewMessage } from "../protocol";
 import {
+    agentAddress,
     editList,
     Field,
     FieldKind,
@@ -207,10 +208,8 @@ function renderList(configs: LaunchConfiguration[], active: LaunchConfiguration
     );
 }
 
-/** host:port of the agent, with the same defaults as the debug session. */
 function address(config: LaunchConfiguration): string {
-    const { host, port } = config.values;
-    return `${String(host ?? "localhost")}:${String(port ?? 1534)}`;
+    return agentAddress(config.values);
 }
 
 /** Start, Duplicate and Delete for one configuration. */
@@ -237,8 +236,8 @@ function itemActions(config: LaunchConfiguration): HTMLElement {
 
 /** Why the configuration cannot be started now, if it cannot. */
 function startProblem(config: LaunchConfiguration): string | undefined {
-    if (state?.debugging) {
-        return "A Simics Target Debug session is already running";
+    if (state?.busyAgents.includes(address(config))) {
+        return `A Simics Target Debug session to ${address(config)} is already running`;
     }
     const empty = (v: unknown) => v === undefined || v === "";
     const emptyCell = (row: unknown, key: string) => empty((row as Record<string, unknown> | null)?.[key]);

src/test/schema.test.ts

@@ -3,6 +3,7 @@ import assert from "node:assert/strict";
 import * as fs from "fs";
 import * as path from "path";
 import {
+    agentAddress,
     editList,
     fieldPath,
     fieldsFromSchema,
@@ -307,3 +308,11 @@ test("parseInput converts typed text to values", () => {
         value: "99999999999999999999",
     });
 });
+
+// The form's start button is only blocked for configurations on an agent that
+// already has a session, so the address must match the debug session's defaults.
+test("agentAddress defaults to the debug session's host and port", () => {
+    assert.equal(agentAddress({}), "localhost:1534");
+    assert.equal(agentAddress({ host: "simhost", port: 1600 }), "simhost:1600");
+    assert.notEqual(agentAddress({ port: 1534 }), agentAddress({ port: 1535 }));
+});