diff --git a/packages/telemetry/src/block-slog.js b/packages/telemetry/src/block-slog.js
new file mode 100644
index 00000000000..b23e8fbc26a
--- /dev/null
+++ b/packages/telemetry/src/block-slog.js
@@ -0,0 +1,153 @@
+/* eslint-env node */
+
+import { open } from 'node:fs/promises';
+import { createGzip } from 'node:zlib';
+import { SLOG_TYPES } from './context-aware-slog.js';
+import { serializeSlogObj } from './serialize-slog-obj.js';
+
+/**
+ * @typedef {import('./context-aware-slog.js').Slog} Slog
+ */
+
+/**
+ * @param {import('./index.js').MakeSlogSenderOptions} options
+ */
+export const makeSlogSender = async options => {
+  const { CONTEXTUAL_BLOCK_SLOGS } = options.env || {};
+  if (!(options.stateDir || CONTEXTUAL_BLOCK_SLOGS))
+    return console.error(
+      'Ignoring invocation of slogger "block-slog" without the presence of "stateDir" or "CONTEXTUAL_BLOCK_SLOGS"',
+    );
+
+  let chainedPromises = Promise.resolve();
+  /**
+   * @type {import('node:fs/promises').FileHandle | null}
+   */
+  let currentFileHandle = null;
+  /**
+   * @type {import('node:fs').WriteStream | null}
+   */
+  let currentFileStream = null;
+  /**
+   * @type {import('node:zlib').Gzip | null}
+   */
+  let currentStream = null;
+
+  /**
+   * @param {Array<() => Promise<void>>} promises
+   */
+  const chainPromises = (...promises) => {
+    for (const promise of promises)
+      chainedPromises = chainedPromises.then(promise);
+  };
+
+  const closeStream = () =>
+    currentStream
+      ? chainPromises(
+          () =>
+            new Promise(resolve =>
+              // @ts-expect-error
+              currentStream.end(() => currentStream.once('finish', resolve)),
+            ),
+          () =>
+            // @ts-expect-error
+            new Promise(resolve => currentFileStream.once('finish', resolve)),
+          async () => {
+            currentStream = null;
+            currentFileStream = null;
+            currentFileHandle = null;
+          },
+        )
+      : console.error('No stream to close');
+
+  /**
+   * @param {string} fileName
+   */
+  const createStream = async fileName => {
+    if (currentStream) throw Error('Stream already open');
+
+    const filePath = `${options.stateDir || CONTEXTUAL_BLOCK_SLOGS}/slogfile_${fileName}.gz`;
+    currentFileHandle = await open(filePath, 'w');
+    currentFileStream = currentFileHandle.createWriteStream();
+    currentStream = createGzip();
+    currentStream.pipe(currentFileStream);
+  };
+
+  /**
+   * @param {Slog} slog
+   */
+  const slogSender = slog => {
+    const { blockHeight, type: slogType } = slog;
+
+    switch (slogType) {
+      case SLOG_TYPES.KERNEL.INIT.START: {
+        chainPromises(() => createStream(`init_${new Date().getTime()}`));
+        break;
+      }
+      case SLOG_TYPES.COSMIC_SWINGSET.BOOTSTRAP_BLOCK.START: {
+        chainPromises(() => createStream(`bootstrap_${new Date().getTime()}`));
+        break;
+      }
+      case SLOG_TYPES.COSMIC_SWINGSET.UPGRADE.START: {
+        chainPromises(() => createStream(`upgrade_${new Date().getTime()}`));
+        break;
+      }
+      case SLOG_TYPES.COSMIC_SWINGSET.BEGIN_BLOCK: {
+        chainPromises(() =>
+          createStream(`block_${blockHeight}_${new Date().getTime()}`),
+        );
+        break;
+      }
+      default: {
+        break;
+      }
+    }
+
+    chainPromises(() => writeSlogToStream(slog));
+
+    switch (slogType) {
+      case SLOG_TYPES.KERNEL.INIT.FINISH:
+      case SLOG_TYPES.COSMIC_SWINGSET.BOOTSTRAP_BLOCK.FINISH:
+      case SLOG_TYPES.COSMIC_SWINGSET.UPGRADE.FINISH:
+      case SLOG_TYPES.COSMIC_SWINGSET.AFTER_COMMIT_STATS: {
+        closeStream();
+        break;
+      }
+      default: {
+        break;
+      }
+    }
+  };
+
+  /**
+   * @param {Slog} slog
+   * @returns {Promise<void>}
+   */
+  const writeSlogToStream = slog =>
+    new Promise(resolve => {
+      if (!currentStream) {
+        console.error(`No stream available for slog type "${slog.type}"`);
+        resolve();
+      } else {
+        // eslint-disable-next-line prefer-template
+        const message = serializeSlogObj(slog) + '\n';
+
+        if (!currentStream.write(message)) currentStream.once('drain', resolve);
+        else resolve();
+      }
+    });
+
+  return Object.assign(slogSender, {
+    forceFlush: () =>
+      chainedPromises.then(
+        () =>
+          /** @type {Promise<void>} */ (
+            new Promise(resolve => currentStream?.flush(resolve))
+          ),
+      ),
+    shutdown: async () => {
+      closeStream();
+      await chainedPromises;
+    },
+  });
+};
diff --git a/packages/telemetry/src/context-aware-slog.js b/packages/telemetry/src/context-aware-slog.js
index ee17acf3dc0..1f4b1cef4b4 100644
--- a/packages/telemetry/src/context-aware-slog.js
+++ b/packages/telemetry/src/context-aware-slog.js
@@ -49,7 +49,7 @@
  * }} Slog
  */
 
-const SLOG_TYPES = {
+export const SLOG_TYPES = {
   CLIST: 'clist',
   CONSOLE: 'console',
   COSMIC_SWINGSET: {
@@ -60,8 +60,8 @@ const SLOG_TYPES = {
       START: 'cosmic-swingset-bootstrap-block-start',
     },
     COMMIT: {
-      FINISH: 'cosmic-swingset-commit-finish',
-      START: 'cosmic-swingset-commit-start',
+      FINISH: 'cosmic-swingset-commit-block-finish',
+      START: 'cosmic-swingset-commit-block-start',
     },
     END_BLOCK: {
       FINISH: 'cosmic-swingset-end-block-finish',
@@ -72,6 +72,10 @@ const SLOG_TYPES = {
       FINISH: 'cosmic-swingset-run-finish',
       START: 'cosmic-swingset-run-start',
     },
+    UPGRADE: {
+      FINISH: 'cosmic-swingset-upgrade-finish',
+      START: 'cosmic-swingset-upgrade-start',
+    },
   },
   COSMIC_SWINGSET_TRIGGERS: {
     BRIDGE_INBOUND: 'cosmic-swingset-bridge-inbound',