diff --git a/.gitignore b/.gitignore
index 1d695e01..e0eb371a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,3 +21,5 @@
 #
 # dist build output
 target/
+capture_config.json
+server/capture_config.json
diff --git a/client/src/CodeMirror-integration.mts b/client/src/CodeMirror-integration.mts
index a1f7e83b..eefa5e26 100644
--- a/client/src/CodeMirror-integration.mts
+++ b/client/src/CodeMirror-integration.mts
@@ -46,7 +46,7 @@
 // 5. Define a set of StateEffects to add/update/etc. doc blocks.
 //
 // Imports
-// -----------------------------------------------------------------------------
+// -------
 //
 // ### Third-party
 import { basicSetup } from "codemirror";
@@ -104,7 +104,7 @@ import { assert } from "./assert.mjs";
 import { show_toast } from "./show_toast.mjs";
 
 // Globals
-// -----------------------------------------------------------------------------
+// -------
 let current_view: EditorView;
 // This indicates that a call to `on_dirty` is scheduled, but hasn't run yet.
 let on_dirty_scheduled = false;
@@ -137,7 +137,7 @@ const exceptionSink = EditorView.exceptionSink.of((exception) => {
 });
 
 // Doc blocks in CodeMirror
-// -----------------------------------------------------------------------------
+// ------------------------
 //
 // The goal: given a [Range](https://codemirror.net/docs/ref/#state.Range) of
 // lines containing a doc block (a delimiter, indent, and contents) residing at
@@ -825,7 +825,7 @@ export const DocBlockPlugin = ViewPlugin.fromClass(
 );
 
 // UI
-// -----------------------------------------------------------------------------
+// --
 //
 // There doesn't seem to be any tracking of a dirty/clean flag built into
 // CodeMirror v6 (although
diff --git a/extensions/VSCode/src/extension.ts b/extensions/VSCode/src/extension.ts
index 02ff419d..e2933241 100644
--- a/extensions/VSCode/src/extension.ts
+++ b/extensions/VSCode/src/extension.ts
@@ -3,7 +3,8 @@
 // This file is part of the CodeChat Editor. The CodeChat Editor is free
 // software: you can redistribute it and/or modify it under the terms of the GNU
 // General Public License as published by the Free Software Foundation, either
-// version 3 of the License, or (at your option) any later version.
+// version 3 of the License, or (at your option) any later version of the GNU
+// General Public License.
 //
 // The CodeChat Editor is distributed in the hope that it will be useful, but
 // WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
@@ -15,13 +16,13 @@
 // [http://www.gnu.org/licenses](http://www.gnu.org/licenses).
 //
 // `extension.ts` - The CodeChat Editor Visual Studio Code extension
-// =============================================================================
+// =================================================================
 //
 // This extension creates a webview, then uses a websocket connection to the
 // CodeChat Editor Server and Client to render editor text in that webview.
 //
 // Imports
-// -----------------------------------------------------------------------------
+// -------
 //
 // ### Node.js packages
 import assert from "assert";
@@ -52,14 +53,20 @@ import {
     MAX_MESSAGE_LENGTH,
 } from "../../../client/src/debug_enabled.mjs";
 import { ResultErrTypes } from "../../../client/src/rust-types/ResultErrTypes.js";
+import * as os from "os";
+
+import * as crypto from "crypto";
 
 // Globals
-// -----------------------------------------------------------------------------
+// -------
 enum CodeChatEditorClientLocation {
     html,
     browser,
 }
 
+// Create a unique session ID for logging
+const CAPTURE_SESSION_ID = crypto.randomUUID();
+
 // True on Windows, false on OS X / Linux.
 const is_windows = process.platform === "win32";
 
@@ -111,8 +118,219 @@ let codeChatEditorServer: CodeChatEditorServer | undefined;
     initServer(ext.extensionPath);
 }
 
+// ---
+//
+// CAPTURE (Dissertation instrumentation)
+// --------------------------------------
+
+function isInMarkdownCodeFence(doc: vscode.TextDocument, line: number): boolean {
+    // Very simple fence tracker: toggles when encountering \`\`\` or ~~~ at
+    // start of line. Good enough for dissertation instrumentation; refine later
+    // if needed.
+    let inFence = false;
+    for (let i = 0; i <= line; i++) {
+        const t = doc.lineAt(i).text.trim();
+        if (t.startsWith("```") || t.startsWith("~~~")) {
+            inFence = !inFence;
+        }
+    }
+    return inFence;
+}
+
+function isInRstCodeBlock(doc: vscode.TextDocument, line: number): boolean {
+    // Heuristic: find the most recent ".. code-block::" (or "::") and see if
+    // we're in its indented region. This won’t be perfect, but it’s far better
+    // than file-level classification.
+    let blockLine = -1;
+    for (let i = line; i >= 0; i--) {
+        const t = doc.lineAt(i).text;
+        const tt = t.trim();
+        if (tt.startsWith(".. code-block::") || tt === "::") {
+            blockLine = i;
+            break;
+        }
+        // If we hit a non-indented line after searching upward too far, keep
+        // going; rst blocks can be separated by blank lines.
+    }
+    if (blockLine < 0) return false;
+
+    // RST code block content usually begins after optional blank line(s),
+    // indented. Determine whether current line is indented relative to block
+    // directive line.
+    const cur = doc.lineAt(line).text;
+    if (cur.trim().length === 0) return false;
+
+    // If it's indented at least one space/tab, treat it as inside block.
+    return /^\s+/.test(cur);
+}
+
+function classifyAtPosition(doc: vscode.TextDocument, pos: vscode.Position): ActivityKind {
+    if (DOC_LANG_IDS.has(doc.languageId)) {
+        if (doc.languageId === "markdown") {
+            return isInMarkdownCodeFence(doc, pos.line) ? "code" : "doc";
+        }
+        if (doc.languageId === "restructuredtext") {
+            return isInRstCodeBlock(doc, pos.line) ? "code" : "doc";
+        }
+        // Other doc types: default to doc
+        return "doc";
+    }
+    return "code";
+}
+
+
+
+// Types for talking to the Rust /capture endpoint. This mirrors
+// `CaptureEventWire` in webserver.rs.
+interface CaptureEventPayload {
+    user_id: string;
+    assignment_id?: string;
+    group_id?: string;
+    file_path?: string;
+    event_type: string;
+    data: any; // sent as JSON
+}
+
+// TODO: replace these with something real (e.g., VS Code settings) For now, we
+// hard-code to prove that the pipeline works end-to-end.
+const CAPTURE_USER_ID: string = (() => {
+    try {
+        const u = os.userInfo().username;
+        if (u && u.trim().length > 0) {
+            return u.trim();
+        }
+    } catch (_) {
+        // fall through
+    }
+
+    // Fallbacks (should rarely be needed)
+    return (
+        process.env["USERNAME"] ||
+        process.env["USER"] ||
+        "unknown-user"
+    );
+})();
+
+const CAPTURE_ASSIGNMENT_ID = "demo-assignment";
+const CAPTURE_GROUP_ID = "demo-group";
+
+// Base URL for the CodeChat server's /capture endpoint. NOTE: keep this in sync
+// with whatever port your server actually uses.
+const CAPTURE_SERVER_BASE = "http://127.0.0.1:8080";
+
+// Simple classification of what the user is currently doing.
+type ActivityKind = "doc" | "code" | "other";
+
+// Language IDs that we treat as "documentation" for the dissertation metrics.
+// You can refine this later if you want.
+const DOC_LANG_IDS = new Set<string>([
+    "markdown",
+    "plaintext",
+    "latex",
+    "restructuredtext",
+]);
+
+// Track the last activity kind and when a reflective-writing (doc) session
+// started.
+let lastActivityKind: ActivityKind = "other";
+let docSessionStart: number | null = null;
+
+// Heuristic: classify a document as documentation vs. code vs. other.
+function classifyDocument(doc: vscode.TextDocument | undefined): ActivityKind {
+    if (!doc) {
+        return "other";
+    }
+    if (DOC_LANG_IDS.has(doc.languageId)) {
+        return "doc";
+    }
+    // Everything else we treat as code for now.
+    return "code";
+}
+
+// Helper to send a capture event to the Rust server.
+async function sendCaptureEvent(
+    serverBaseUrl: string, // e.g. "http://127.0.0.1:8080"
+    eventType: string,
+    filePath?: string,
+    data: any = {},
+): Promise<void> {
+    const payload: CaptureEventPayload = {
+        user_id: CAPTURE_USER_ID,
+        assignment_id: CAPTURE_ASSIGNMENT_ID,
+        group_id: CAPTURE_GROUP_ID,
+        file_path: filePath,
+        event_type: eventType,
+        data: {
+            ...data,
+            session_id: CAPTURE_SESSION_ID,
+            client_timestamp_ms: Date.now(),
+            client_tz_offset_min: new Date().getTimezoneOffset(),
+        },
+    };
+
+    try {
+        const resp = await fetch(`${serverBaseUrl}/capture`, {
+            method: "POST",
+            headers: {
+                "Content-Type": "application/json",
+            },
+            body: JSON.stringify(payload),
+        });
+
+        if (!resp.ok) {
+            console.error(
+                "Capture event failed:",
+                resp.status,
+                await resp.text(),
+            );
+        }
+    } catch (err) {
+        console.error("Error sending capture event:", err);
+    }
+}
+
+// Update activity state, emit switch + doc\_session events as needed.
+function noteActivity(kind: ActivityKind, filePath?: string) {
+    const now = Date.now();
+
+    // Handle entering / leaving a "doc" session.
+    if (kind === "doc") {
+        if (docSessionStart === null) {
+            // Starting a new reflective-writing session.
+            docSessionStart = now;
+            void sendCaptureEvent(CAPTURE_SERVER_BASE, "session_start", filePath, {
+                mode: "doc",
+            });
+        }
+    } else {
+        if (docSessionStart !== null) {
+            // Ending a reflective-writing session.
+            const durationMs = now - docSessionStart;
+            docSessionStart = null;
+            void sendCaptureEvent(CAPTURE_SERVER_BASE, "doc_session", filePath, {
+                duration_ms: durationMs,
+                duration_seconds: durationMs / 1000.0,
+            });
+            void sendCaptureEvent(CAPTURE_SERVER_BASE, "session_end", filePath, {
+                mode: "doc",
+            });
+        }
+    }
+
+    // If we switched between doc and code, log a switch\_pane event.
+    const docOrCode = (k: ActivityKind) => k === "doc" || k === "code";
+    if (docOrCode(lastActivityKind) && docOrCode(kind) && kind !== lastActivityKind) {
+        void sendCaptureEvent(CAPTURE_SERVER_BASE, "switch_pane", filePath, {
+            from: lastActivityKind,
+            to: kind,
+        });
+    }
+
+    lastActivityKind = kind;
+}
+
 // Activation/deactivation
-// -----------------------------------------------------------------------------
+// -----------------------
 //
 // This is invoked when the extension is activated. It either creates a new
 // CodeChat Editor Server instance or reveals the currently running one.
@@ -127,6 +345,18 @@ export const activate = (context: vscode.ExtensionContext) => {
             async () => {
                 console_log("CodeChat Editor extension: starting.");
 
+                // CAPTURE: mark the start of an editor session.
+                const active = vscode.window.activeTextEditor;
+                const startFilePath = active?.document.fileName;
+                void sendCaptureEvent(
+                    CAPTURE_SERVER_BASE,
+                    "session_start",
+                    startFilePath,
+                    {
+                        mode: "vscode_extension",
+                    },
+                );
+
                 if (!subscribed) {
                     subscribed = true;
 
@@ -148,6 +378,48 @@ export const activate = (context: vscode.ExtensionContext) => {
                                     event.reason
                                 }, ${format_struct(event.contentChanges)}.`,
                             );
+
+                            // CAPTURE: classify this as documentation vs. code
+                            // and log a write\_\* event.
+                            const doc = event.document;
+// ```
+//                        const kind = classifyDocument(doc);
+// ```
+                            const firstChange = event.contentChanges[0];
+                            const pos = firstChange.range.start;
+                            const kind = classifyAtPosition(doc, pos);
+
+                            const filePath = doc.fileName;
+                            const charsTyped = event.contentChanges
+                                .map((c) => c.text.length)
+                                .reduce((a, b) => a + b, 0);
+
+                            if (kind === "doc") {
+                                void sendCaptureEvent(
+                                    CAPTURE_SERVER_BASE,
+                                    "write_doc",
+                                    filePath,
+                                    {
+                                        chars_typed: charsTyped,
+                                        languageId: doc.languageId,
+                                    },
+                                );
+                            } else if (kind === "code") {
+                                void sendCaptureEvent(
+                                    CAPTURE_SERVER_BASE,
+                                    "write_code",
+                                    filePath,
+                                    {
+                                        chars_typed: charsTyped,
+                                        languageId: doc.languageId,
+                                    },
+                                );
+                            }
+
+                            // Update our notion of current activity + doc
+                            // session.
+                            noteActivity(kind, filePath);
+
                             send_update(true);
                         }),
                     );
@@ -172,23 +444,132 @@ export const activate = (context: vscode.ExtensionContext) => {
                             ) {
                                 return;
                             }
+
+                            // CAPTURE: update activity + possible
+                            // switch\_pane/doc\_session.
+                            const doc = event.document;
+                            // const kind = classifyDocument(doc);
+                            const pos = event.selection?.active ?? new vscode.Position(0, 0);
+                            const kind = classifyAtPosition(doc, pos);
+
+                            const filePath = doc.fileName;
+                            noteActivity(kind, filePath);
+
                             send_update(true);
                         }),
                     );
 
                     context.subscriptions.push(
-                        vscode.window.onDidChangeTextEditorSelection(
-                            (_event) => {
-                                if (ignore_selection_change) {
-                                    ignore_selection_change = false;
-                                    return;
-                                }
-                                console_log(
-                                    "CodeChat Editor extension: sending updated cursor/scroll position.",
-                                );
-                                send_update(false);
-                            },
-                        ),
+                        vscode.window.onDidChangeTextEditorSelection((event) => {
+                            if (ignore_selection_change) {
+                                ignore_selection_change = false;
+                                return;
+                            }
+
+                            console_log(
+                                "CodeChat Editor extension: sending updated cursor/scroll position.",
+                            );
+
+                            // CAPTURE: treat a selection change as "activity"
+                            // in this document.
+                            const doc = event.textEditor.document;
+                            // const kind = classifyDocument(doc);
+                            const pos = event.selections?.[0]?.active ?? event.textEditor.selection.active;
+                            const kind = classifyAtPosition(doc, pos);
+                            const filePath = doc.fileName;
+                            noteActivity(kind, filePath);
+
+                            send_update(false);
+                        }),
+                    );
+
+                    // CAPTURE: end of a debug/run session.
+                    context.subscriptions.push(
+                        vscode.debug.onDidTerminateDebugSession((session) => {
+                            const active = vscode.window.activeTextEditor;
+                            const filePath = active?.document.fileName;
+                            void sendCaptureEvent(
+                                CAPTURE_SERVER_BASE,
+                                "run_end",
+                                filePath,
+                                {
+                                    sessionName: session.name,
+                                    sessionType: session.type,
+                                },
+                            );
+                        }),
+                    );
+
+                    // CAPTURE: compile/build end events via VS Code tasks.
+                    context.subscriptions.push(
+                        vscode.tasks.onDidEndTaskProcess((e) => {
+                            const active = vscode.window.activeTextEditor;
+                            const filePath = active?.document.fileName;
+                            const task = e.execution.task;
+                            void sendCaptureEvent(
+                                CAPTURE_SERVER_BASE,
+                                "compile_end",
+                                filePath,
+                                {
+                                    taskName: task.name,
+                                    taskSource: task.source,
+                                    exitCode: e.exitCode,
+                                },
+                            );
+                        }),
+                    );
+
+                    // CAPTURE: listen for file saves.
+                    context.subscriptions.push(
+                        vscode.workspace.onDidSaveTextDocument((doc) => {
+                            void sendCaptureEvent(
+                                CAPTURE_SERVER_BASE,
+                                "save",
+                                doc.fileName,
+                                {
+                                    reason: "manual_save",
+                                    languageId: doc.languageId,
+                                    lineCount: doc.lineCount,
+                                },
+                            );
+                        }),
+                    );
+
+                    // CAPTURE: start of a debug/run session.
+                    context.subscriptions.push(
+                        vscode.debug.onDidStartDebugSession((session) => {
+                            const active = vscode.window.activeTextEditor;
+                            const filePath = active?.document.fileName;
+                            void sendCaptureEvent(
+                                CAPTURE_SERVER_BASE,
+                                "run",
+                                filePath,
+                                {
+                                    sessionName: session.name,
+                                    sessionType: session.type,
+                                },
+                            );
+                        }),
+                    );
+
+                    // CAPTURE: compile/build events via VS Code tasks.
+                    context.subscriptions.push(
+                        vscode.tasks.onDidStartTaskProcess((e) => {
+                            const active = vscode.window.activeTextEditor;
+                            const filePath = active?.document.fileName;
+                            const task = e.execution.task;
+                            void sendCaptureEvent(
+                                CAPTURE_SERVER_BASE,
+                                "compile",
+                                filePath,
+                                {
+                                    taskName: task.name,
+                                    taskSource: task.source,
+                                    definition: task.definition,
+                                    processId: e.processId,
+                                },
+                            );
+                        }),
                     );
                 }
 
@@ -200,13 +581,11 @@ export const activate = (context: vscode.ExtensionContext) => {
                 assert(typeof codechat_client_location_str === "string");
                 switch (codechat_client_location_str) {
                     case "html":
-                        codechat_client_location =
-                            CodeChatEditorClientLocation.html;
+                        codechat_client_location = CodeChatEditorClientLocation.html;
                         break;
 
                     case "browser":
-                        codechat_client_location =
-                            CodeChatEditorClientLocation.browser;
+                        codechat_client_location = CodeChatEditorClientLocation.browser;
                         break;
 
                     default:
@@ -215,45 +594,24 @@ export const activate = (context: vscode.ExtensionContext) => {
 
                 // Create or reveal the webview panel; if this is an external
                 // browser, we'll open it after the client is created.
-                if (
-                    codechat_client_location ===
-                    CodeChatEditorClientLocation.html
-                ) {
+                if (codechat_client_location === CodeChatEditorClientLocation.html) {
                     if (webview_panel !== undefined) {
-                        // As below, don't take the focus when revealing.
                         webview_panel.reveal(undefined, true);
                     } else {
-                        // Create a webview panel.
                         webview_panel = vscode.window.createWebviewPanel(
                             "CodeChat Editor",
                             "CodeChat Editor",
                             {
-                                // Without this, the focus becomes this webview;
-                                // setting this allows the code window open
-                                // before this command was executed to retain
-                                // the focus and be immediately rendered.
                                 preserveFocus: true,
-                                // Put this in the a column beside the current
-                                // column.
                                 viewColumn: vscode.ViewColumn.Beside,
                             },
-                            // See
-                            // [WebViewOptions](https://code.visualstudio.com/api/references/vscode-api#WebviewOptions).
                             {
                                 enableScripts: true,
-                                // Without this, the websocket connection is
-                                // dropped when the panel is hidden.
                                 retainContextWhenHidden: true,
                             },
                         );
                         webview_panel.onDidDispose(async () => {
-                            // Shut down the render client when the webview
-                            // panel closes.
-                            console_log(
-                                "CodeChat Editor extension: shut down webview.",
-                            );
-                            // Closing the webview abruptly closes the Client,
-                            // which produces an error. Don't report it.
+                            console_log("CodeChat Editor extension: shut down webview.");
                             quiet_next_error = true;
                             webview_panel = undefined;
                             await stop_client();
@@ -261,13 +619,10 @@ export const activate = (context: vscode.ExtensionContext) => {
                     }
                 }
 
-                // Provide a simple status display while the CodeChat Editor
-                // Server is starting up.
+                // Provide a simple status display while the server is starting
+                // up.
                 if (webview_panel !== undefined) {
-                    // If we have an ID, then the GUI is already running; don't
-                    // replace it.
-                    webview_panel.webview.html =
-                        "<h1>CodeChat Editor</h1><p>Loading...</p>";
+                    webview_panel.webview.html = "<h1>CodeChat Editor</h1><p>Loading...</p>";
                 } else {
                     vscode.window.showInformationMessage(
                         "The CodeChat Editor is loading in an external browser...",
@@ -279,19 +634,13 @@ export const activate = (context: vscode.ExtensionContext) => {
                 codeChatEditorServer = new CodeChatEditorServer();
 
                 const hosted_in_ide =
-                    codechat_client_location ===
-                    CodeChatEditorClientLocation.html;
+                    codechat_client_location === CodeChatEditorClientLocation.html;
                 console_log(
                     `CodeChat Editor extension: sending message Opened(${hosted_in_ide}).`,
                 );
                 await codeChatEditorServer.sendMessageOpened(hosted_in_ide);
-                // For the external browser, we can immediately send the
-                // `CurrentFile` message. For the WebView, we must first wait to
-                // receive the HTML for the WebView (the `ClientHtml` message).
-                if (
-                    codechat_client_location ===
-                    CodeChatEditorClientLocation.browser
-                ) {
+
+                if (codechat_client_location === CodeChatEditorClientLocation.browser) {
                     send_update(false);
                 }
 
@@ -301,10 +650,8 @@ export const activate = (context: vscode.ExtensionContext) => {
                         console_log("CodeChat Editor extension: queue closed.");
                         break;
                     }
-                    // Parse the data into a message.
-                    const { id, message } = JSON.parse(
-                        message_raw,
-                    ) as EditorMessage;
+
+                    const { id, message } = JSON.parse(message_raw) as EditorMessage;
                     console_log(
                         `CodeChat Editor extension: Received data id = ${id}, message = ${format_struct(
                             message,
@@ -321,11 +668,9 @@ export const activate = (context: vscode.ExtensionContext) => {
                         keys[0] as KeysOfRustEnum<EditorMessageContents>;
                     const value = Object.values(message)[0];
 
-                    // Process this message.
                     switch (key) {
                         case "Update": {
-                            const current_update =
-                                value as UpdateMessageContents;
+                            const current_update = value as UpdateMessageContents;
                             const doc = get_document(current_update.file_path);
                             if (doc === undefined) {
                                 await sendResult(id, {
@@ -335,34 +680,23 @@ export const activate = (context: vscode.ExtensionContext) => {
                             }
                             if (current_update.contents !== undefined) {
                                 const source = current_update.contents.source;
-                                // This will produce a change event, which we'll
-                                // ignore. The change may also produce a
-                                // selection change, which should also be
-                                // ignored.
+
                                 ignore_text_document_change = true;
                                 ignore_selection_change = true;
-                                // Use a workspace edit, since calls to
-                                // `TextEditor.edit` must be made to the active
-                                // editor only.
+
                                 const wse = new vscode.WorkspaceEdit();
-                                // Is this plain text, or a diff?
+
                                 if ("Plain" in source) {
                                     wse.replace(
                                         doc.uri,
                                         doc.validateRange(
-                                            new vscode.Range(
-                                                0,
-                                                0,
-                                                doc.lineCount,
-                                                0,
-                                            ),
+                                            new vscode.Range(0, 0, doc.lineCount, 0),
                                         ),
                                         source.Plain.doc,
                                     );
                                 } else {
                                     assert("Diff" in source);
-                                    // If this diff was not made against the
-                                    // text we currently have, reject it.
+
                                     if (source.Diff.version !== version) {
                                         await sendResult(id, {
                                             OutOfSync: [
@@ -380,26 +714,12 @@ export const activate = (context: vscode.ExtensionContext) => {
                                     }
                                     const diffs = source.Diff.doc;
                                     for (const diff of diffs) {
-                                        // Convert from character offsets from the
-                                        // beginning of the document to a
-                                        // `Position` (line, then offset on that
-                                        // line) needed by VSCode.
                                         const from = doc.positionAt(diff.from);
                                         if (diff.to === undefined) {
-                                            // This is an insert.
-                                            wse.insert(
-                                                doc.uri,
-                                                from,
-                                                diff.insert,
-                                            );
+                                            wse.insert(doc.uri, from, diff.insert);
                                         } else {
-                                            // This is a replace or delete.
                                             const to = doc.positionAt(diff.to);
-                                            wse.replace(
-                                                doc.uri,
-                                                new Range(from, to),
-                                                diff.insert,
-                                            );
+                                            wse.replace(doc.uri, new Range(from, to), diff.insert);
                                         }
                                     }
                                 }
@@ -407,30 +727,17 @@ export const activate = (context: vscode.ExtensionContext) => {
                                 ignore_text_document_change = false;
                                 ignore_selection_change = false;
 
-                                // Now that we've updated our text, update the
-                                // associated version as well.
                                 version = current_update.contents.version;
                             }
 
-                            // Update the cursor and scroll position if
-                            // provided.
                             const editor = get_text_editor(doc);
+
                             const scroll_line = current_update.scroll_position;
                             if (scroll_line !== undefined && editor) {
                                 ignore_selection_change = true;
-                                const scroll_position = new vscode.Position(
-                                    // The VSCode line is zero-based; the
-                                    // CodeMirror line is one-based.
-                                    scroll_line - 1,
-                                    0,
-                                );
+                                const scroll_position = new vscode.Position(scroll_line - 1, 0);
                                 editor.revealRange(
-                                    new vscode.Range(
-                                        scroll_position,
-                                        scroll_position,
-                                    ),
-                                    // This is still not the top of the
-                                    // viewport, but a bit below it.
+                                    new vscode.Range(scroll_position, scroll_position),
                                     TextEditorRevealType.AtTop,
                                 );
                             }
@@ -438,17 +745,9 @@ export const activate = (context: vscode.ExtensionContext) => {
                             const cursor_line = current_update.cursor_position;
                             if (cursor_line !== undefined && editor) {
                                 ignore_selection_change = true;
-                                const cursor_position = new vscode.Position(
-                                    // The VSCode line is zero-based; the
-                                    // CodeMirror line is one-based.
-                                    cursor_line - 1,
-                                    0,
-                                );
+                                const cursor_position = new vscode.Position(cursor_line - 1, 0);
                                 editor.selections = [
-                                    new vscode.Selection(
-                                        cursor_position,
-                                        cursor_position,
-                                    ),
+                                    new vscode.Selection(cursor_position, cursor_position),
                                 ];
                             }
                             await sendResult(id);
@@ -461,25 +760,18 @@ export const activate = (context: vscode.ExtensionContext) => {
                             if (is_text) {
                                 let document;
                                 try {
-                                    document =
-                                        await vscode.workspace.openTextDocument(
-                                            current_file,
-                                        );
+                                    document = await vscode.workspace.openTextDocument(current_file);
                                 } catch (e) {
                                     await sendResult(id, {
-                                        OpenFileFailed: [
-                                            current_file,
-                                            (e as Error).toString(),
-                                        ],
+                                        OpenFileFailed: [current_file, (e as Error).toString()],
                                     });
                                     continue;
                                 }
                                 ignore_active_editor_change = true;
-                                current_editor =
-                                    await vscode.window.showTextDocument(
-                                        document,
-                                        current_editor?.viewColumn,
-                                    );
+                                current_editor = await vscode.window.showTextDocument(
+                                    document,
+                                    current_editor?.viewColumn,
+                                );
                                 ignore_active_editor_change = false;
                                 await sendResult(id);
                             } else {
@@ -497,19 +789,13 @@ export const activate = (context: vscode.ExtensionContext) => {
                                         .executeCommand(
                                             "vscode.open",
                                             vscode.Uri.file(current_file),
-                                            {
-                                                viewColumn:
-                                                    current_editor?.viewColumn,
-                                            },
+                                            { viewColumn: current_editor?.viewColumn },
                                         )
                                         .then(
                                             async () => await sendResult(id),
                                             async (reason) =>
                                                 await sendResult(id, {
-                                                    OpenFileFailed: [
-                                                        current_file,
-                                                        reason,
-                                                    ],
+                                                    OpenFileFailed: [current_file, reason],
                                                 }),
                                         );
                                 */
@@ -519,7 +805,6 @@ export const activate = (context: vscode.ExtensionContext) => {
                         }
 
                         case "Result": {
-                            // Report if this was an error.
                             const result_contents = value as MessageResult;
                             if ("Err" in result_contents) {
                                 const err = result_contents[
@@ -566,10 +851,7 @@ export const activate = (context: vscode.ExtensionContext) => {
                             console_log(
                                 `CodeChat Editor extension: Result(LoadFile(id = ${id}, ${format_struct(load_file_result)}))`,
                             );
-                            await codeChatEditorServer.sendResultLoadfile(
-                                id,
-                                load_file_result,
-                            );
+                            await codeChatEditorServer.sendResultLoadfile(id, load_file_result);
                             break;
                         }
 
@@ -578,17 +860,13 @@ export const activate = (context: vscode.ExtensionContext) => {
                             assert(webview_panel !== undefined);
                             webview_panel.webview.html = client_html;
                             await sendResult(id);
-                            // Now that the Client is loaded, send the editor's
-                            // current file to the server.
                             send_update(false);
                             break;
                         }
 
                         default:
                             console.error(
-                                `Unhandled message ${key}(${format_struct(
-                                    value,
-                                )}`,
+                                `Unhandled message ${key}(${format_struct(value)}`,
                             );
                             break;
                     }
@@ -601,13 +879,41 @@ export const activate = (context: vscode.ExtensionContext) => {
 // On deactivation, close everything down.
 export const deactivate = async () => {
     console_log("CodeChat Editor extension: deactivating.");
+
+    // CAPTURE: if we were in a doc session, close it out so duration is
+    // recorded.
+    if (docSessionStart !== null) {
+        const now = Date.now();
+        const durationMs = now - docSessionStart;
+        docSessionStart = null;
+        const active = vscode.window.activeTextEditor;
+        const filePath = active?.document.fileName;
+
+        await sendCaptureEvent(CAPTURE_SERVER_BASE, "doc_session", filePath, {
+            duration_ms: durationMs,
+            duration_seconds: durationMs / 1000.0,
+            closed_by: "extension_deactivate",
+        });
+        await sendCaptureEvent(CAPTURE_SERVER_BASE, "session_end", filePath, {
+            mode: "doc",
+            closed_by: "extension_deactivate",
+        });
+    }
+
+    // CAPTURE: mark the end of an editor session.
+    const active = vscode.window.activeTextEditor;
+    const endFilePath = active?.document.fileName;
+    await sendCaptureEvent(CAPTURE_SERVER_BASE, "session_end", endFilePath, {
+        mode: "vscode_extension",
+    });
+
     await stop_client();
     webview_panel?.dispose();
     console_log("CodeChat Editor extension: deactivated.");
 };
 
 // Supporting functions
-// -----------------------------------------------------------------------------
+// --------------------
 //
 // Format a complex data structure as a string when in debug mode.
 /*eslint-disable-next-line @typescript-eslint/no-explicit-any */
@@ -623,7 +929,9 @@ const format_struct = (complex_data_structure: any): string =>
 const sendResult = async (id: number, result?: ResultErrTypes) => {
     assert(codeChatEditorServer);
     console_log(
-        `CodeChat Editor extension: sending Result(id = ${id}, ${format_struct(result)}).`,
+        `CodeChat Editor extension: sending Result(id = ${id}, ${format_struct(
+            result,
+        )}).`,
     );
     try {
         await codeChatEditorServer.sendResult(
@@ -641,56 +949,41 @@ const sendResult = async (id: number, result?: ResultErrTypes) => {
 const send_update = (this_is_dirty: boolean) => {
     is_dirty ||= this_is_dirty;
     if (can_render()) {
-        // Render after some inactivity: cancel any existing timer, then ...
         if (idle_timer !== undefined) {
             clearTimeout(idle_timer);
         }
-        // ... schedule a render after an autosave timeout.
         idle_timer = setTimeout(async () => {
             if (can_render()) {
                 const ate = vscode.window.activeTextEditor;
                 if (ate !== undefined && ate !== current_editor) {
-                    // Send a new current file after a short delay; this allows
-                    // the user to rapidly cycle through several editors without
-                    // needing to reload the Client with each cycle.
                     current_editor = ate;
-                    const current_file = ate!.document.fileName;
+                    const current_file = ate.document.fileName;
                     console_log(
                         `CodeChat Editor extension: sending CurrentFile(${current_file}}).`,
                     );
                     try {
-                        await codeChatEditorServer!.sendMessageCurrentFile(
-                            current_file,
-                        );
+                        await codeChatEditorServer!.sendMessageCurrentFile(current_file);
                     } catch (e) {
                         show_error(`Error sending CurrentFile message: ${e}.`);
                     }
-                    // Since we just requested a new file, the contents are
-                    // clean by definition.
                     is_dirty = false;
-                    // Don't send an updated cursor position until this file is
-                    // loaded.
                     return;
                 }
 
-                // The
-                // [Position](https://code.visualstudio.com/api/references/vscode-api#Position)
-                // encodes the line as a zero-based value. In contrast,
-                // CodeMirror
-                // [Text.line](https://codemirror.net/docs/ref/#state.Text.line)
-                // is 1-based.
-                const cursor_position =
-                    current_editor!.selection.active.line + 1;
+                const cursor_position = current_editor!.selection.active.line + 1;
                 const scroll_position =
                     current_editor!.visibleRanges[0].start.line + 1;
                 const file_path = current_editor!.document.fileName;
-                // Send contents only if necessary.
+
                 const option_contents: null | [string, number] = is_dirty
                     ? [current_editor!.document.getText(), (version = rand())]
                     : null;
                 is_dirty = false;
+
                 console_log(
-                    `CodeChat Editor extension: sending Update(${file_path}, ${cursor_position}, ${scroll_position}, ${format_struct(option_contents)})`,
+                    `CodeChat Editor extension: sending Update(${file_path}, ${cursor_position}, ${scroll_position}, ${format_struct(
+                        option_contents,
+                    )})`,
                 );
                 await codeChatEditorServer!.sendMessageUpdatePlain(
                     file_path,
@@ -713,8 +1006,6 @@ const stop_client = async () => {
         codeChatEditorServer = undefined;
     }
 
-    // Shut the timer down after the client is undefined, to ensure it can't be
-    // started again by a call to `start_render()`.
     if (idle_timer !== undefined) {
         clearTimeout(idle_timer);
         idle_timer = undefined;
@@ -731,10 +1022,7 @@ const show_error = (message: string) => {
     }
     console.error(`CodeChat Editor extension: ${message}`);
     if (webview_panel !== undefined) {
-        // If the panel was displaying other content, reset it for errors.
-        if (
-            !webview_panel.webview.html.startsWith("<h1>CodeChat Editor</h1>")
-        ) {
+        if (!webview_panel.webview.html.startsWith("<h1>CodeChat Editor</h1>")) {
             webview_panel.webview.html = "<h1>CodeChat Editor</h1>";
         }
         webview_panel.webview.html += `<p style="white-space: pre-wrap;">${escape(
@@ -754,35 +1042,16 @@ const can_render = () => {
         (vscode.window.activeTextEditor !== undefined ||
             current_editor !== undefined) &&
         codeChatEditorServer !== undefined &&
-        // TODO: I don't think these matter -- the Server is in charge of
-        // sending output to the Client.
         (codechat_client_location === CodeChatEditorClientLocation.browser ||
             webview_panel !== undefined)
     );
 };
 
 const get_document = (file_path: string) => {
-    // Look through all open documents to see if we have the requested file.
-    for (const doc of vscode.workspace.textDocuments) {
-        // Make the possibly incorrect assumption that only Windows filesystems
-        // are case-insensitive; I don't know how to easily determine the
-        // case-sensitivity of the current filesystem without extra probing code
-        // (write a file in mixed case, try to open it in another mixed case.)
-        // Per
-        // [How to Work with Different Filesystems](https://nodejs.org/en/learn/manipulating-files/working-with-different-filesystems#filesystem-behavior),
-        // "Be wary of inferring filesystem behavior from `process.platform`.
-        // For example, do not assume that because your program is running on
-        // Darwin that you are therefore working on a case-insensitive
-        // filesystem (HFS+), as the user may be using a case-sensitive
-        // filesystem (HFSX)."
-        //
-        // The same article
-        // [recommends](https://nodejs.org/en/learn/manipulating-files/working-with-different-filesystems#be-prepared-for-slight-differences-in-comparison-functions)
-        // using `toUpperCase` for case-insensitive filename comparisons.
+    for ( const doc of vscode.workspace.textDocuments) {
         if (
             (!is_windows && doc.fileName === file_path) ||
-            (is_windows &&
-                doc.fileName.toUpperCase() === file_path.toUpperCase())
+            (is_windows && doc.fileName.toUpperCase() === file_path.toUpperCase())
         ) {
             return doc;
         }
@@ -802,3 +1071,16 @@ const console_log = (...args: any) => {
         console.log(...args);
     }
 };
+
+function getCurrentUsername(): string {
+  try {
+    // Most reliable on Windows/macOS/Linux
+    const u = os.userInfo().username;
+    if (u && u.trim().length > 0) return u.trim();
+  } catch (_) {}
+
+  // Fallbacks
+  const envUser = process.env["USERNAME"] || process.env["USER"];
+  return (envUser && envUser.trim().length > 0) ? envUser.trim() : "unknown-user";
+}
+
diff --git a/server/log4rs.yml b/server/log4rs.yml
index 544068f2..d534ba2a 100644
--- a/server/log4rs.yml
+++ b/server/log4rs.yml
@@ -40,7 +40,7 @@ loggers:
     level: warn
 
 root:
-  level: info
+  level: debug
   appenders:
     - console_appender
     - file_appender
\ No newline at end of file
diff --git a/server/src/capture.rs b/server/src/capture.rs
index 3f8f7c15..fd7eede9 100644
--- a/server/src/capture.rs
+++ b/server/src/capture.rs
@@ -13,227 +13,603 @@
 // You should have received a copy of the GNU General Public License along with
 // the CodeChat Editor. If not, see
 // [http://www.gnu.org/licenses](http://www.gnu.org/licenses).
-/// # `Capture.rs` -- Capture CodeChat Editor Events
-// ## Submodules
-//
-// ## Imports
-//
-// Standard library
-use indoc::indoc;
-use std::fs;
+
+/// `capture.rs` -- Capture CodeChat Editor Events
+/// ============================================================================
+///
+/// This module provides an asynchronous event capture facility backed by a
+/// PostgreSQL database. It is designed to support the dissertation study by
+/// recording process-level data such as:
+///
+/// * Frequency and timing of writing entries
+/// * Edits to documentation and code
+/// * Switches between documentation and coding activity
+/// * Duration of engagement with reflective writing
+/// * Save, compile, and run events
+///
+/// Events are sent from the client (browser and/or VS Code extension) to the
+/// server as JSON. The server enqueues events into an asynchronous worker which
+/// performs batched inserts into the `events` table.
+///
+/// Database schema
+/// ----------------------------------------------------------------------------
+///
+/// The following SQL statement creates the `events` table used by this module:
+///
+/// ```sql
+/// CREATE TABLE events (
+///     id            SERIAL PRIMARY KEY,
+///     user_id       TEXT NOT NULL,
+///     assignment_id TEXT,
+///     group_id      TEXT,
+///     file_path     TEXT,
+///     event_type    TEXT NOT NULL,
+///     timestamp     TEXT NOT NULL,
+///     data          TEXT
+/// );
+/// ```
+///
+/// * `user_id` – participant identifier (student id, pseudonym, etc.).
+/// * `assignment_id` – logical assignment / lab identifier.
+/// * `group_id` – optional grouping (treatment / comparison, section).
+/// * `file_path` – logical path of the file being edited.
+/// * `event_type` – coarse event type (see `event_type` constants below).
+/// * `timestamp` – RFC3339 timestamp (in UTC).
+/// * `data` – JSON payload with event-specific details.
+
 use std::io;
-use std::path::Path;
-use std::sync::Arc;
 
-// Third-party
-use chrono::Local;
-use log::{error, info};
+use chrono::{DateTime, Utc};
+use log::{debug, error, info, warn};
 use serde::{Deserialize, Serialize};
-use tokio::sync::Mutex;
+use tokio::sync::mpsc;
 use tokio_postgres::{Client, NoTls};
+use std::error::Error;
+
+/// Canonical event type strings. Keep these stable for analysis.
+pub mod event_types {
+    pub const WRITE_DOC: &str = "write_doc";
+    pub const WRITE_CODE: &str = "write_code";
+    pub const SWITCH_PANE: &str = "switch_pane";
+    pub const DOC_SESSION: &str = "doc_session"; // duration of reflective writing
+    pub const SAVE: &str = "save";
+    pub const COMPILE: &str = "compile";
+    pub const RUN: &str = "run";
+    pub const SESSION_START: &str = "session_start";
+    pub const SESSION_END: &str = "session_end";
+    pub const COMPILE_END: &str = "compile_end";
+    pub const RUN_END: &str = "run_end";
+}
 
-// Local
-
-/* ## The Event Structure:
-
-   The `Event` struct represents an event to be stored in the database.
-
-   Fields: - `user_id`: The ID of the user associated with the event. -
-   `event_type`: The type of event (e.g., "keystroke", "file_open"). - `data`:
-   Optional additional data associated with the event.
-
-   ### Example
+/// Configuration used to construct the PostgreSQL connection string.
+///
+/// You can populate this from a JSON file or environment variables in
+/// `main.rs`; this module stays agnostic.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct CaptureConfig {
+    pub host: String,
+    pub user: String,
+    pub password: String,
+    pub dbname: String,
+    /// Optional: application-level identifier for this deployment (e.g., course
+    /// code or semester). Not stored in the DB directly; callers can embed this
+    /// in `data` if desired.
+    #[serde(default)]
+    pub app_id: Option<String>,
+}
 
-   let event = Event { user_id: "user123".to_string(), event_type:
-   "keystroke".to_string(), data: Some("Pressed key A".to_string()), };
-*/
+impl CaptureConfig {
+    /// Build a libpq-style connection string.
+    pub fn to_conn_str(&self) -> String {
+        format!(
+            "host={} user={} password={} dbname={}",
+            self.host, self.user, self.password, self.dbname
+        )
+    }
+}
 
-#[derive(Deserialize, Debug)]
-pub struct Event {
+/// The in-memory representation of a single capture event.
+#[derive(Debug, Clone)]
+pub struct CaptureEvent {
     pub user_id: String,
+    pub assignment_id: Option<String>,
+    pub group_id: Option<String>,
+    pub file_path: Option<String>,
     pub event_type: String,
-    pub data: Option<String>,
+    /// When the event occurred, in UTC.
+    pub timestamp: DateTime<Utc>,
+    /// Event-specific payload, stored as JSON text in the DB.
+    pub data: serde_json::Value,
 }
 
-/*
-    ## The Config Structure:
-
-    The `Config` struct represents the database connection parameters read from
-   `config.json`.
+impl CaptureEvent {
+    /// Convenience constructor when the caller already has a timestamp.
+    pub fn new(
+        user_id: String,
+        assignment_id: Option<String>,
+        group_id: Option<String>,
+        file_path: Option<String>,
+        event_type: impl Into<String>,
+        timestamp: DateTime<Utc>,
+        data: serde_json::Value,
+    ) -> Self {
+        Self {
+            user_id,
+            assignment_id,
+            group_id,
+            file_path,
+            event_type: event_type.into(),
+            timestamp,
+            data,
+        }
+    }
 
-   Fields: - `db_host`: The hostname or IP address of the database server. -
-   `db_user`: The username for the database connection. - `db_password`: The
-   password for the database connection. - `db_name`: The name of the database.
+    /// Convenience constructor which uses the current time.
+    pub fn now(
+        user_id: String,
+        assignment_id: Option<String>,
+        group_id: Option<String>,
+        file_path: Option<String>,
+        event_type: impl Into<String>,
+        data: serde_json::Value,
+    ) -> Self {
+        Self::new(
+            user_id,
+            assignment_id,
+            group_id,
+            file_path,
+            event_type,
+            Utc::now(),
+            data,
+        )
+    }
+}
 
-   let config = Config { db_host: "localhost".to_string(), db_user:
-   "your_db_user".to_string(), db_password: "your_db_password".to_string(),
-   db_name: "your_db_name".to_string(), };
-*/
+/// Internal worker message. Identical to `CaptureEvent`, but separated in case
+/// we later want to add batching / flush control signals.
+type WorkerMsg = CaptureEvent;
 
-#[derive(Deserialize, Serialize, Debug)]
-pub struct Config {
-    pub db_ip: String,
-    pub db_user: String,
-    pub db_password: String,
-    pub db_name: String,
+/// Handle used by the rest of the server to record events.
+///
+/// Cloning this handle is cheap: it only clones an `mpsc::UnboundedSender`.
+#[derive(Clone)]
+pub struct EventCapture {
+    tx: mpsc::UnboundedSender<WorkerMsg>,
 }
 
-/*
+impl EventCapture {
+    /// Create a new `EventCapture` instance and spawn a background worker which
+    /// consumes events and inserts them into PostgreSQL.
+    ///
+    /// This function is synchronous so it can be called from non-async server
+    /// setup code. It spawns an async task internally which performs the
+    /// database connection and event processing.
+    pub fn new(config: CaptureConfig) -> Result<Self, io::Error> {
+        let conn_str = config.to_conn_str();
+
+        // High-level DB connection details (no password).
+        info!(
+            "Capture: preparing PostgreSQL connection (host={}, dbname={}, user={}, app_id={:?})",
+            config.host, config.dbname, config.user, config.app_id
+        );
+        debug!("Capture: raw PostgreSQL connection string: {}", conn_str);
 
- ## The EventCapture Structure:
+        let (tx, mut rx) = mpsc::unbounded_channel::<WorkerMsg>();
 
- The `EventCapture` struct provides methods to interact with the database. It
-holds a `tokio_postgres::Client` for database operations.
+        // Spawn a background task that will connect to PostgreSQL and then
+        // process events. This task runs on the Tokio/Actix runtime once the
+        // system starts, so the caller does not need to be async.
+        tokio::spawn(async move {
+            info!("Capture: attempting to connect to PostgreSQL…");
+
+            match tokio_postgres::connect(&conn_str, NoTls).await {
+                Ok((client, connection)) => {
+                    info!("Capture: successfully connected to PostgreSQL.");
+
+                    // Drive the connection in its own task.
+                    tokio::spawn(async move {
+                        if let Err(err) = connection.await {
+                            error!("Capture PostgreSQL connection error: {err}");
+                        }
+                    });
+
+                    // Main event loop: pull events off the channel and insert
+                    // them into the database.
+                    while let Some(event) = rx.recv().await {
+                        debug!(
+                            "Capture: inserting event: type={}, user_id={}, assignment_id={:?}, group_id={:?}, file_path={:?}",
+                            event.event_type,
+                            event.user_id,
+                            event.assignment_id,
+                            event.group_id,
+                            event.file_path
+                        );
+
+                        if let Err(err) = insert_event(&client, &event).await {
+                            error!(
+                                "Capture: FAILED to insert event (type={}, user_id={}): {err}",
+                                event.event_type, event.user_id
+                            );
+                        } else {
+                            debug!("Capture: event insert successful.");
+                        }
+                    }
+
+                    info!("Capture: event channel closed; background worker exiting.");
+                }
+
+Err(err) => {
+    let ctx = format!(
+        "Capture: FAILED to connect to PostgreSQL (host={}, dbname={}, user={})",
+        config.host, config.dbname, config.user
+    );
+
+    log_pg_connect_error(&ctx, &err);
+
+    // Drain and drop any events so we don't hold the sender.
+    warn!("Capture: draining pending events after failed DB connection.");
+    while rx.recv().await.is_some() {}
+    warn!("Capture: all pending events dropped due to connection failure.");
+}
 
-### Usage Example
+                // Err(err) => { // NOTE: we *don't* pass `err` twice here;
+                // `{err}` in the format // string already grabs the local `err`
+                // binding. error!( "Capture: FAILED to connect to PostgreSQL
+                // (host={}, dbname={}, user={}): {err}", config.host,
+                // config.dbname, config.user, ); // Drain and drop any events
+                // so we don't hold the sender. warn!("Capture: draining pending
+                // events after failed DB connection."); while
+                // rx.recv().await.is\_some() {} warn!("Capture: all pending
+                // events dropped due to connection failure."); }
+            }
+        });
 
-#\[tokio::main\] async fn main() -> Result<(), Box> {
+        Ok(Self { tx })
+    }
 
-```
- // Create an instance of EventCapture using the configuration file
- let event_capture = EventCapture::new("config.json").await?;
+    /// Enqueue an event for insertion. This is non-blocking.
+    pub fn log(&self, event: CaptureEvent) {
+        debug!(
+            "Capture: queueing event: type={}, user_id={}, assignment_id={:?}, group_id={:?}, file_path={:?}",
+            event.event_type,
+            event.user_id,
+            event.assignment_id,
+            event.group_id,
+            event.file_path
+        );
 
- // Create an event
- let event = Event {
-     user_id: "user123".to_string(),
-     event_type: "keystroke".to_string(),
-     data: Some("Pressed key A".to_string()),
- };
+        if let Err(err) = self.tx.send(event) {
+            error!("Capture: FAILED to enqueue capture event: {err}");
+        }
+    }
+}
 
- // Insert the event into the database
- event_capture.insert_event(event).await?;
+fn log_pg_connect_error(context: &str, err: &tokio_postgres::Error) {
+    // If Postgres returned a structured DbError, log it ONCE and bail.
+    if let Some(db) = err.as_db_error() {
+        // Example: 28P01 = invalid\_password
+        error!(
+            "{context}: PostgreSQL {} (SQLSTATE {})",
+            db.message(),
+            db.code().code()
+        );
 
- Ok(())
-```
-} */
+        if let Some(detail) = db.detail() {
+            error!("{context}: detail: {detail}");
+        }
+        if let Some(hint) = db.hint() {
+            error!("{context}: hint: {hint}");
+        }
+        return;
+    }
 
-pub struct EventCapture {
-    db_client: Arc<Mutex<Client>>,
+    // Otherwise, try to find an underlying std::io::Error (refused, timed out,
+    // DNS, etc.)
+    let mut current: &(dyn Error + 'static) = err;
+    while let Some(source) = current.source() {
+        if let Some(ioe) = source.downcast_ref::<std::io::Error>() {
+            error!(
+                "{context}: I/O error kind={:?} raw_os_error={:?} msg={}",
+                ioe.kind(),
+                ioe.raw_os_error(),
+                ioe
+            );
+            return;
+        }
+        current = source;
+    }
+
+    // Fallback: log once (Display)
+    error!("{context}: {err}");
 }
 
-/*
-    ## The EventCapture Implementation
-*/
 
-impl EventCapture {
-    /*
-        Creates a new `EventCapture` instance by reading the database connection parameters from the `config.json` file and connecting to the PostgreSQL database.
-            # Arguments
-            - config_path: The file path to the config.json file.
 
-            # Returns
+/// Insert a single event into the `events` table.
+async fn insert_event(client: &Client, event: &CaptureEvent) -> Result<u64, tokio_postgres::Error> {
+    let timestamp = event.timestamp.to_rfc3339();
+    let data_text = event.data.to_string();
+
+    debug!(
+        "Capture: executing INSERT for user_id={}, event_type={}, timestamp={}",
+        event.user_id, event.event_type, timestamp
+    );
+
+    client
+        .execute(
+            "INSERT INTO events \
+             (user_id, assignment_id, group_id, file_path, event_type, timestamp, data) \
+             VALUES ($1, $2, $3, $4, $5, $6, $7)",
+            &[
+                &event.user_id,
+                &event.assignment_id,
+                &event.group_id,
+                &event.file_path,
+                &event.event_type,
+                &timestamp,
+                &data_text,
+            ],
+        )
+        .await
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+
+    #[test]
+    fn capture_config_to_conn_str_is_well_formed() {
+        let cfg = CaptureConfig {
+            host: "localhost".to_string(),
+            user: "alice".to_string(),
+            password: "secret".to_string(),
+            dbname: "codechat_capture".to_string(),
+            app_id: Some("spring25-study".to_string()),
+        };
+
+        let conn = cfg.to_conn_str();
+        // Very simple checks: we don't care about ordering beyond what we
+        // format.
+        assert!(conn.contains("host=localhost"));
+        assert!(conn.contains("user=alice"));
+        assert!(conn.contains("password=secret"));
+        assert!(conn.contains("dbname=codechat_capture"));
+    }
 
-            A `Result` containing an `EventCapture` instance
-    */
+    #[test]
+    fn capture_event_new_sets_all_fields() {
+        let ts = Utc::now();
+
+        let ev = CaptureEvent::new(
+            "user123".to_string(),
+            Some("lab1".to_string()),
+            Some("groupA".to_string()),
+            Some("/path/to/file.rs".to_string()),
+            "write_doc",
+            ts,
+            json!({ "chars_typed": 42 }),
+        );
 
-    pub async fn new<P: AsRef<Path>>(config_path: P) -> Result<Self, io::Error> {
-        // Read the configuration file
-        let config_content = fs::read_to_string(config_path).map_err(io::Error::other)?;
-        let config: Config = serde_json::from_str(&config_content)
-            .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?;
+        assert_eq!(ev.user_id, "user123");
+        assert_eq!(ev.assignment_id.as_deref(), Some("lab1"));
+        assert_eq!(ev.group_id.as_deref(), Some("groupA"));
+        assert_eq!(ev.file_path.as_deref(), Some("/path/to/file.rs"));
+        assert_eq!(ev.event_type, "write_doc");
+        assert_eq!(ev.timestamp, ts);
+        assert_eq!(ev.data, json!({ "chars_typed": 42 }));
+    }
 
-        // Build the connection string for the PostgreSQL database
-        let conn_str = format!(
-            "host={} user={} password={} dbname={}",
-            config.db_ip, config.db_user, config.db_password, config.db_name
+    #[test]
+    fn capture_event_now_uses_current_time_and_fields() {
+        let before = Utc::now();
+        let ev = CaptureEvent::now(
+            "user123".to_string(),
+            None,
+            None,
+            None,
+            "save",
+            json!({ "reason": "manual" }),
         );
+        let after = Utc::now();
+
+        assert_eq!(ev.user_id, "user123");
+        assert!(ev.assignment_id.is_none());
+        assert!(ev.group_id.is_none());
+        assert!(ev.file_path.is_none());
+        assert_eq!(ev.event_type, "save");
+        assert_eq!(ev.data, json!({ "reason": "manual" }));
+
+        // Timestamp sanity check: it should be between before and after
+        assert!(ev.timestamp >= before);
+        assert!(ev.timestamp <= after);
+    }
 
-        info!(
-            "Attempting Capture Database Connection. IP:[{}] Username:[{}] Database Name:[{}]",
-            config.db_ip, config.db_user, config.db_name
+    #[test]
+    fn capture_config_json_round_trip() {
+        let json_text = r#"
+        {
+            "host": "db.example.com",
+            "user": "bob",
+            "password": "hunter2",
+            "dbname": "cc_events",
+            "app_id": "fall25"
+        }
+        "#;
+
+        let cfg: CaptureConfig = serde_json::from_str(json_text).expect("JSON should parse");
+        assert_eq!(cfg.host, "db.example.com");
+        assert_eq!(cfg.user, "bob");
+        assert_eq!(cfg.password, "hunter2");
+        assert_eq!(cfg.dbname, "cc_events");
+        assert_eq!(cfg.app_id.as_deref(), Some("fall25"));
+
+        // And it should serialize back to JSON without error
+        let _back = serde_json::to_string(&cfg).expect("Should serialize");
+    }
+
+    use std::fs;
+    //use tokio::time::{sleep, Duration};
+
+    /// Integration-style test: verify that EventCapture actually inserts into
+    /// the DB.
+    ///
+    /// Reads connection parameters from `capture_config.json` in the current
+    /// working directory. Logs the config and connection details via log4rs so
+    /// you can confirm what is used.
+    ///
+    /// Run this test with: cargo test event\_capture\_inserts\_event\_into\_db
+    /// -- --ignored --nocapture
+    ///
+    /// You must have a PostgreSQL database and a `capture_config.json` file
+    /// such as: { "host": "localhost", "user": "codechat\_test\_user",
+    /// "password": "codechat\_test\_password", "dbname":
+    /// "codechat\_capture\_test", "app\_id": "integration-test" }
+    #[tokio::test]
+    #[ignore]
+    async fn event_capture_inserts_event_into_db() -> Result<(), Box<dyn std::error::Error>> {
+
+        // Initialize logging for this test, using the same log4rs.yml as the
+        // server. If logging is already initialized, this will just return an
+        // error which we ignore.
+        let _ = log4rs::init_file("log4rs.yml", Default::default());
+
+        // 1. Load the capture configuration from file.
+        let cfg_text = fs::read_to_string("capture_config.json")
+            .expect("capture_config.json must exist in project root for this test");
+        let cfg: CaptureConfig =
+            serde_json::from_str(&cfg_text).expect("capture_config.json must be valid JSON");
+
+        log::info!(
+            "TEST: Loaded DB config from capture_config.json: host={}, user={}, dbname={}, app_id={:?}",
+            cfg.host,
+            cfg.user,
+            cfg.dbname,
+            cfg.app_id
         );
 
-        // Connect to the database asynchronously
-        let (client, connection) = tokio_postgres::connect(&conn_str, NoTls)
-            .await
-            .map_err(|e| io::Error::new(io::ErrorKind::ConnectionRefused, e))?;
+        // 2. Connect directly for setup + verification.
+        let conn_str = cfg.to_conn_str();
+        log::info!("TEST: Attempting direct tokio_postgres connection for verification.");
 
-        // Spawn a task to manage the database connection in the background
+        let (client, connection) = tokio_postgres::connect(&conn_str, NoTls).await?;
         tokio::spawn(async move {
             if let Err(e) = connection.await {
-                error!("Database connection error: [{e}]");
+                log::error!("TEST: direct connection error: {e}");
             }
         });
 
-        info!(
-            "Connected to Database [{}] as User [{}]",
-            config.db_name, config.db_user
+        // Verify the events table already exists
+        let row = client
+            .query_one(
+                r#"
+                SELECT EXISTS (
+                    SELECT 1
+                    FROM information_schema.tables
+                    WHERE table_schema = 'public'
+                    AND table_name   = 'events'
+                ) AS exists
+                "#,
+                &[],
+            )
+            .await?;
+
+        let exists: bool = row.get("exists");
+        assert!(
+            exists,
+            "TEST SETUP ERROR: public.events table does not exist. \
+            It must be created by a migration or admin step."
         );
 
-        Ok(EventCapture {
-            db_client: Arc::new(Mutex::new(client)),
-        })
-    }
+        // Insert a single test row (this is what the app really needs)
+        let test_user_id = format!(
+            "TEST_USER_{}",
+            std::time::SystemTime::now()
+                .duration_since(std::time::UNIX_EPOCH)
+                .unwrap()
+                .as_millis()
+        );
 
-    /*
-       Inserts an event into the database.
-
-       # Arguments
-       - `event`: An `Event` instance containing the event data to insert.
-
-       # Returns
-       A `Result` indicating success or containing a `tokio_postgres::Error`.
-
-       # Example
-       #[tokio::main]
-       async fn main() -> Result<(), Box<dyn std::error::Error>> {
-           let event_capture = EventCapture::new("config.json").await?;
-
-           let event = Event {
-               user_id: "user123".to_string(),
-               event_type: "keystroke".to_string(),
-               data: Some("Pressed key A".to_string()),
-           };
-
-           event_capture.insert_event(event).await?;
-           Ok(())
-       }
-    */
-
-    pub async fn insert_event(&self, event: Event) -> Result<(), io::Error> {
-        let current_time = Local::now();
-        let formatted_time = current_time.to_rfc3339();
-
-        // SQL statement to insert the event into the 'events' table
-        let stmt = indoc! {"
-            INSERT INTO events (user_id, event_type, timestamp, data)
-            VALUES ($1, $2, $3, $4)
-        "};
-
-        // Acquire a lock on the database client for thread-safe access
-        let client = self.db_client.lock().await;
-
-        // Execute the SQL statement with the event data
-        client
-            .execute(
-                stmt,
-                &[
-                    &event.user_id,
-                    &event.event_type,
-                    &formatted_time,
-                    &event.data,
-                ],
+        let insert_row = client
+            .query_one(
+                r#"
+                INSERT INTO public.events
+                    (user_id, assignment_id, group_id, file_path, event_type, timestamp, data)
+                VALUES
+                    ($1, NULL, NULL, NULL, 'test_event', $2, '{"test":true}')
+                RETURNING id
+                "#,
+                &[&test_user_id, &format!("{:?}", std::time::SystemTime::now())],
             )
-            .await
-            .map_err(io::Error::other)?;
-
-        info!("Event inserted into database: {event:?}");
+            .await?;
+
+        let inserted_id: i32 = insert_row.get("id");
+        info!("TEST: inserted event id={}", inserted_id);
+
+        // 4. Start the EventCapture worker using the loaded config.
+        let capture = EventCapture::new(cfg.clone())?;
+        log::info!("TEST: EventCapture worker started.");
+
+        // 5. Log a test event.
+        let expected_data = json!({ "chars_typed": 123 });
+        let event = CaptureEvent::now(
+            "test-user".to_string(),
+            Some("hw1".to_string()),
+            Some("groupA".to_string()),
+            Some("/tmp/test.rs".to_string()),
+            event_types::WRITE_DOC,
+            expected_data.clone(),
+        );
 
+        log::info!("TEST: logging a test capture event.");
+        capture.log(event);
+
+        // 6. Wait (deterministically) for the background worker to insert the event,
+        // then fetch THAT row (instead of "latest row in the table").
+        use tokio::time::{sleep, Duration, Instant};
+
+        let deadline = Instant::now() + Duration::from_secs(2);
+
+        let row = loop {
+            match client
+                .query_one(
+                    r#"
+                    SELECT user_id, assignment_id, group_id, file_path, event_type, data
+                    FROM events
+                    WHERE user_id = $1 AND event_type = $2
+                    ORDER BY id DESC
+                    LIMIT 1
+                    "#,
+                    &[&"test-user", &event_types::WRITE_DOC],
+                )
+                .await
+            {
+                Ok(row) => break row, // found it
+                Err(_) => {
+                    if Instant::now() >= deadline {
+                        return Err("Timed out waiting for EventCapture insert".into());
+                    }
+                    sleep(Duration::from_millis(50)).await;
+                }
+            }
+        };
+
+        let user_id: String = row.get(0);
+        let assignment_id: Option<String> = row.get(1);
+        let group_id: Option<String> = row.get(2);
+        let file_path: Option<String> = row.get(3);
+        let event_type: String = row.get(4);
+        let data_text: String = row.get(5);
+        let data_value: serde_json::Value = serde_json::from_str(&data_text)?;
+
+        assert_eq!(user_id, "test-user");
+        assert_eq!(assignment_id.as_deref(), Some("hw1"));
+        assert_eq!(group_id.as_deref(), Some("groupA"));
+        assert_eq!(file_path.as_deref(), Some("/tmp/test.rs"));
+        assert_eq!(event_type, event_types::WRITE_DOC);
+        assert_eq!(data_value, expected_data);
+
+        log::info!("✅ TEST: EventCapture integration test succeeded and wrote to database.");
         Ok(())
     }
 }
-
-/* Database Schema (SQL DDL)
-
-The following SQL statement creates the `events` table used by this library:
-
-CREATE TABLE events ( id SERIAL PRIMARY KEY, user_id TEXT NOT NULL,
-event_type TEXT NOT NULL, timestamp TEXT NOT NULL, data TEXT );
-
-- **`id SERIAL PRIMARY KEY`**: Auto-incrementing primary key.
-- **`user_id TEXT NOT NULL`**: The ID of the user associated with the event.
-- **`event_type TEXT NOT NULL`**: The type of event.
-- **`timestamp TEXT NOT NULL`**: The timestamp of the event.
-- **`data TEXT`**: Optional additional data associated with the event.
-  **Note:** Ensure this table exists in your PostgreSQL database before using
-  the library. */
diff --git a/server/src/webserver.rs b/server/src/webserver.rs
index 145172c5..c963bab7 100644
--- a/server/src/webserver.rs
+++ b/server/src/webserver.rs
@@ -37,15 +37,17 @@ use std::{
 
 // ### Third-party
 use actix_files;
+
 use actix_web::{
     App, HttpRequest, HttpResponse, HttpServer,
     dev::{Server, ServerHandle, ServiceFactory, ServiceRequest},
     error::Error,
-    get,
+    get, post,
     http::header::{ContentType, DispositionType},
     middleware,
     web::{self, Data},
 };
+
 use actix_web_httpauth::{extractors::basic::BasicAuth, middleware::HttpAuthentication};
 use actix_ws::AggregatedMessage;
 use bytes::Bytes;
@@ -93,6 +95,10 @@ use crate::{
     },
 };
 
+use crate::capture::{EventCapture, CaptureConfig, CaptureEvent};
+
+use chrono::Utc;
+
 // Data structures
 // -----------------------------------------------------------------------------
 //
@@ -378,6 +384,8 @@ pub struct AppState {
     pub connection_id: Arc<Mutex<HashSet<String>>>,
     /// The auth credentials if authentication is used.
     credentials: Option<Credentials>,
+    // Added to support capture - JDS - 11/2025
+    pub capture: Option<EventCapture>,    
 }
 
 pub type WebAppState = web::Data<AppState>;
@@ -388,6 +396,28 @@ pub struct Credentials {
     pub password: String,
 }
 
+/// JSON payload received from clients for capture events.
+///
+/// The server will supply the timestamp; clients do not need to send it.
+#[derive(Debug, Deserialize)]
+pub struct CaptureEventWire {
+    pub user_id: String,
+    pub assignment_id: Option<String>,
+    pub group_id: Option<String>,
+    pub file_path: Option<String>,
+    pub event_type: String,
+
+    /// Optional client-side timestamp (milliseconds since Unix epoch).
+    pub client_timestamp_ms: Option<i64>,
+
+    /// Optional client timezone offset in minutes (JS Date().getTimezoneOffset()).
+    pub client_tz_offset_min: Option<i32>,
+
+    /// Arbitrary event-specific data stored as JSON (optional).
+    pub data: Option<serde_json::Value>,
+}
+
+
 // Macros
 // -----------------------------------------------------------------------------
 /// Create a macro to report an error when enqueueing an item.
@@ -571,6 +601,51 @@ async fn stop(app_state: WebAppState) -> HttpResponse {
     HttpResponse::NoContent().finish()
 }
 
+#[post("/capture")]
+async fn capture_endpoint(
+    app_state: WebAppState,
+    payload: web::Json<CaptureEventWire>,
+) -> HttpResponse {
+    let wire = payload.into_inner();
+
+ if let Some(capture) = &app_state.capture {
+    // Default missing data to empty object
+    let mut data = wire.data.unwrap_or_else(|| serde_json::json!({}));
+
+    // Ensure data is an object so we can attach fields
+    if !data.is_object() {
+        data = serde_json::json!({ "value": data });
+    }
+
+    // Add client timestamp fields if present (even if extension also sends them;
+    // overwriting is fine and consistent).
+    if let serde_json::Value::Object(map) = &mut data {
+        if let Some(ms) = wire.client_timestamp_ms {
+            map.insert("client_timestamp_ms".to_string(), serde_json::json!(ms));
+        }
+        if let Some(tz) = wire.client_tz_offset_min {
+            map.insert("client_tz_offset_min".to_string(), serde_json::json!(tz));
+        }
+    }
+
+    let event = CaptureEvent {
+        user_id: wire.user_id,
+        assignment_id: wire.assignment_id,
+        group_id: wire.group_id,
+        file_path: wire.file_path,
+        event_type: wire.event_type,
+        // Server decides when the event is recorded.
+        timestamp: Utc::now(),
+        data,
+    };
+
+    capture.log(event);
+}
+
+
+    HttpResponse::Ok().finish()
+}
+
 // Get the `mode` query parameter to determine `is_test_mode`; default to
 // `false`.
 pub fn get_test_mode(req: &HttpRequest) -> bool {
@@ -1414,8 +1489,6 @@ pub fn setup_server(
     addr: &SocketAddr,
     credentials: Option<Credentials>,
 ) -> std::io::Result<(Server, Data<AppState>)> {
-    // Connect to the Capture Database
-    //let _event_capture = EventCapture::new("config.json").await?;
 
     // Pre-load the bundled files before starting the webserver.
     let _ = &*BUNDLED_FILES_MAP;
@@ -1496,6 +1569,42 @@ pub fn configure_logger(level: LevelFilter) -> Result<(), Box<dyn std::error::Er
 // inside `configure_app` places it inside the closure which calls
 // `configure_app`, preventing globally shared state.
 pub fn make_app_data(credentials: Option<Credentials>) -> WebAppState {
+    // Initialize event capture from a config file (optional).
+    let capture: Option<EventCapture> = {
+        // Build path: <ROOT_PATH>/capture_config.json
+        let mut config_path = ROOT_PATH.lock().unwrap().clone();
+        config_path.push("capture_config.json");
+
+        match fs::read_to_string(&config_path) {
+            Ok(json) => {
+                match serde_json::from_str::<CaptureConfig>(&json) {
+                    Ok(cfg) => match EventCapture::new(cfg) {
+                        Ok(ec) => {
+                            eprintln!("Capture: enabled (config file: {config_path:?})");
+                            Some(ec)
+                        }
+                        Err(err) => {
+                            eprintln!("Capture: failed to initialize from {config_path:?}: {err}");
+                            None
+                        }
+                    },
+                    Err(err) => {
+                        eprintln!(
+                            "Capture: invalid JSON in {config_path:?}: {err}"
+                        );
+                        None
+                    }
+                }
+            }
+            Err(err) => {
+                eprintln!(
+                    "Capture: disabled (config file not found or unreadable: {config_path:?}: {err})"
+                );
+                None
+            }
+        }
+    };
+
     web::Data::new(AppState {
         server_handle: Mutex::new(None),
         filewatcher_next_connection_id: Mutex::new(0),
@@ -1506,6 +1615,7 @@ pub fn make_app_data(credentials: Option<Credentials>) -> WebAppState {
         client_queues: Arc::new(Mutex::new(HashMap::new())),
         connection_id: Arc::new(Mutex::new(HashSet::new())),
         credentials,
+        capture,
     })
 }
 
@@ -1535,6 +1645,7 @@ where
         .service(vscode_client_framework)
         .service(ping)
         .service(stop)
+        .service(capture_endpoint)        
         // Reroute to the filewatcher filesystem for typical user-requested
         // URLs.
         .route("/", web::get().to(filewatcher_root_fs_redirect))