diff --git a/.local/bin/lightcontrol b/.local/bin/lightcontrol
index 2fc0340..f39acb2 100755
--- a/.local/bin/lightcontrol
+++ b/.local/bin/lightcontrol
@@ -27,6 +27,13 @@ delta_change() {
   set_brightness "$((curr_brightness + $1))"
 }
 
+require_value() {
+  if [[ $# -lt 1 ]]; then
+    echo "$usage" >&2
+    exit 1
+  fi
+}
+
 main() {
   [[ -z ${1:-} ]] && return
   case "$1" in
@@ -41,11 +48,13 @@ main() {
     ;;
   -d)
     shift
+    require_value "$@"
     delta_change "$1"
     exit 0
     ;;
   -s)
     shift
+    require_value "$@"
     set_brightness "$1"
     exit 0
     ;;
diff --git a/home/.pi/agent/extensions/copy.ts b/home/.pi/agent/extensions/copy.ts
new file mode 100644
index 0000000..e530316
--- /dev/null
+++ b/home/.pi/agent/extensions/copy.ts
@@ -0,0 +1,178 @@
+import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
+import { spawn } from "node:child_process";
+
+export interface ClipboardCandidate {
+  command: string;
+  args: string[];
+}
+
+type RecordLike = Record<string, unknown>;
+
+function isRecord(value: unknown): value is RecordLike {
+  return value !== null && typeof value === "object";
+}
+
+export function extractAssistantText(message: unknown): string {
+  if (!isRecord(message) || message.role !== "assistant") {
+    return "";
+  }
+
+  const content = message.content;
+  if (typeof content === "string") {
+    return content;
+  }
+  if (!Array.isArray(content)) {
+    return "";
+  }
+
+  const textBlocks: string[] = [];
+  for (const block of content) {
+    if (!isRecord(block) || block.type !== "text" || typeof block.text !== "string") {
+      continue;
+    }
+    if (block.text.length > 0) {
+      textBlocks.push(block.text);
+    }
+  }
+
+  return textBlocks.join("\n\n");
+}
+
+export function findLastAssistantText(entries: readonly unknown[]): string | null {
+  for (let index = entries.length - 1; index >= 0; index--) {
+    const entry = entries[index];
+    if (!isRecord(entry) || entry.type !== "message") {
+      continue;
+    }
+
+    const text = extractAssistantText(entry.message);
+    if (text.length > 0) {
+      return text;
+    }
+  }
+
+  return null;
+}
+
+export function getClipboardCandidates(
+  platform: NodeJS.Platform = process.platform,
+  env: NodeJS.ProcessEnv = process.env,
+): ClipboardCandidate[] {
+  if (platform === "darwin") {
+    return [{ command: "pbcopy", args: [] }];
+  }
+
+  if (platform === "win32") {
+    return [{ command: "clip.exe", args: [] }];
+  }
+
+  if (platform === "linux") {
+    const candidates: ClipboardCandidate[] = [];
+    if (env.WAYLAND_DISPLAY) {
+      candidates.push({ command: "wl-copy", args: [] });
+    }
+    candidates.push(
+      { command: "xclip", args: ["-selection", "clipboard"] },
+      { command: "xsel", args: ["--clipboard", "--input"] },
+    );
+    return candidates;
+  }
+
+  return [];
+}
+
+export async function copyTextToClipboard(text: string): Promise<void> {
+  const candidates = getClipboardCandidates();
+  const errors: string[] = [];
+
+  for (const candidate of candidates) {
+    try {
+      await runClipboardCommand(candidate, text);
+      return;
+    } catch (error) {
+      errors.push(formatClipboardError(candidate.command, error));
+    }
+  }
+
+  if (candidates.length === 0) {
+    throw new Error(`No clipboard command configured for ${process.platform}`);
+  }
+
+  throw new Error(`Clipboard copy failed: ${errors.join("; ")}`);
+}
+
+async function runClipboardCommand(candidate: ClipboardCandidate, text: string): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const child = spawn(candidate.command, candidate.args, {
+      stdio: ["pipe", "ignore", "pipe"],
+    });
+    let stderr = "";
+    let settled = false;
+
+    function finish(error?: Error) {
+      if (settled) return;
+      settled = true;
+      if (error) {
+        reject(error);
+      } else {
+        resolve();
+      }
+    }
+
+    child.stderr?.setEncoding("utf8");
+    child.stderr?.on("data", (chunk: string) => {
+      stderr += chunk;
+    });
+    child.stdin.on("error", () => {
+      // The child can close stdin early on failure; the close event reports the failure.
+    });
+    child.on("error", finish);
+    child.on("close", (code) => {
+      if (code === 0) {
+        finish();
+        return;
+      }
+      const details = stderr.trim() || `exit code ${code ?? "unknown"}`;
+      finish(new Error(details));
+    });
+
+    child.stdin.end(text, "utf8");
+  });
+}
+
+function formatClipboardError(command: string, error: unknown): string {
+  if (error instanceof Error && error.message.length > 0) {
+    return `${command}: ${error.message}`;
+  }
+  return `${command}: unknown error`;
+}
+
+export default function (pi: ExtensionAPI) {
+  pi.registerCommand("copy", {
+    description: "Copy the last visible assistant message to the clipboard",
+    handler: async (_args, ctx) => {
+      await ctx.waitForIdle();
+
+      const text = findLastAssistantText(ctx.sessionManager.getBranch());
+      if (text === null) {
+        if (ctx.hasUI) {
+          ctx.ui.notify("No assistant message to copy", "warning");
+        }
+        return;
+      }
+
+      try {
+        await copyTextToClipboard(text);
+      } catch (error) {
+        if (ctx.hasUI) {
+          ctx.ui.notify(formatClipboardError("/copy", error), "error");
+        }
+        return;
+      }
+
+      if (ctx.hasUI) {
+        ctx.ui.notify("Copied last assistant message", "info");
+      }
+    },
+  });
+}
diff --git a/home/.pi/agent/extensions/tests/copy.test.ts b/home/.pi/agent/extensions/tests/copy.test.ts
new file mode 100644
index 0000000..776653f
--- /dev/null
+++ b/home/.pi/agent/extensions/tests/copy.test.ts
@@ -0,0 +1,71 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { extractAssistantText, findLastAssistantText, getClipboardCandidates } from "../copy.ts";
+
+test("extractAssistantText returns visible text blocks only", () => {
+  const text = extractAssistantText({
+    role: "assistant",
+    content: [
+      { type: "thinking", thinking: "private reasoning" },
+      { type: "text", text: "First visible paragraph." },
+      { type: "toolCall", name: "bash", id: "call_1", arguments: { command: "echo hi" } },
+      { type: "text", text: "Second visible paragraph." },
+    ],
+  });
+
+  assert.equal(text, "First visible paragraph.\n\nSecond visible paragraph.");
+});
+
+test("findLastAssistantText returns newest assistant text from the active branch", () => {
+  const text = findLastAssistantText([
+    {
+      type: "message",
+      message: { role: "assistant", content: [{ type: "text", text: "Older assistant" }] },
+    },
+    {
+      type: "message",
+      message: { role: "user", content: [{ type: "text", text: "Please continue" }] },
+    },
+    {
+      type: "message",
+      message: {
+        role: "assistant",
+        content: [
+          { type: "thinking", thinking: "hidden" },
+          { type: "text", text: "Newest assistant" },
+        ],
+      },
+    },
+  ]);
+
+  assert.equal(text, "Newest assistant");
+});
+
+test("findLastAssistantText skips assistant messages without visible text", () => {
+  const text = findLastAssistantText([
+    {
+      type: "message",
+      message: { role: "assistant", content: [{ type: "text", text: "Copy me" }] },
+    },
+    {
+      type: "message",
+      message: { role: "assistant", content: [{ type: "thinking", thinking: "hidden only" }] },
+    },
+  ]);
+
+  assert.equal(text, "Copy me");
+});
+
+test("getClipboardCandidates prefers platform clipboard commands", () => {
+  assert.deepEqual(getClipboardCandidates("darwin", {}), [{ command: "pbcopy", args: [] }]);
+  assert.deepEqual(getClipboardCandidates("linux", { WAYLAND_DISPLAY: "wayland-1" }), [
+    { command: "wl-copy", args: [] },
+    { command: "xclip", args: ["-selection", "clipboard"] },
+    { command: "xsel", args: ["--clipboard", "--input"] },
+  ]);
+  assert.deepEqual(getClipboardCandidates("linux", {}), [
+    { command: "xclip", args: ["-selection", "clipboard"] },
+    { command: "xsel", args: ["--clipboard", "--input"] },
+  ]);
+});
diff --git a/tests/compress-preserves-existing-archive.sh b/tests/compress-preserves-existing-archive.sh
deleted file mode 100644
index 0b96195..0000000
--- a/tests/compress-preserves-existing-archive.sh
+++ /dev/null
@@ -1,63 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-repo_root=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
-tmp=$(mktemp -d)
-trap 'rm -rf "$tmp"' EXIT
-
-mkdir -p "$tmp/bin" "$tmp/input"
-printf 'sentinel\n' >"$tmp/archive.tar"
-printf 'payload\n' >"$tmp/input/file.txt"
-
-cat >"$tmp/bin/zstd" <<'ZSTD'
-#!/usr/bin/env bash
-set -euo pipefail
-
-remove=false
-input=
-output=
-
-while (($#)); do
-  case "$1" in
-    --rm)
-      remove=true
-      shift
-      ;;
-    -o)
-      output=$2
-      shift 2
-      ;;
-    -*)
-      shift
-      ;;
-    *)
-      input=$1
-      shift
-      ;;
-  esac
-done
-
-if [[ -z $input || -z $output ]]; then
-  echo 'zstd stub missing input or output' >&2
-  exit 1
-fi
-
-cp "$input" "$output"
-if [[ $remove == true ]]; then
-  rm -f "$input"
-fi
-ZSTD
-chmod +x "$tmp/bin/zstd"
-
-(
-  cd "$tmp"
-  PATH="$tmp/bin:$PATH" "$repo_root/.local/bin/compress" input >/dev/null
-)
-
-actual=$(cat "$tmp/archive.tar")
-if [[ $actual != 'sentinel' ]]; then
-  echo 'compress modified an existing archive.tar in the working directory' >&2
-  exit 1
-fi
-
-[[ -s "$tmp/archive.tar.zst" ]]
\ No newline at end of file
diff --git a/tests/dumpcert-default-port.sh b/tests/dumpcert-default-port.sh
deleted file mode 100644
index 650152a..0000000
--- a/tests/dumpcert-default-port.sh
+++ /dev/null
@@ -1,38 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-repo_root=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
-tmp=$(mktemp -d)
-trap 'rm -rf "$tmp"' EXIT
-
-cat >"$tmp/openssl" <<'OPENSSL'
-#!/usr/bin/env bash
-set -euo pipefail
-
-if [[ ${1:-} == s_client ]]; then
-  printf '%s\n' "$*" >"$OPENSSL_ARGS_FILE"
-  printf '%s\n' '-----BEGIN CERTIFICATE-----' 'stub' '-----END CERTIFICATE-----'
-  exit 0
-fi
-
-if [[ ${1:-} == x509 ]]; then
-  cat >/dev/null
-  printf 'decoded certificate\n'
-  exit 0
-fi
-
-echo "unexpected openssl invocation: $*" >&2
-exit 1
-OPENSSL
-chmod +x "$tmp/openssl"
-
-OPENSSL_ARGS_FILE="$tmp/openssl.args" PATH="$tmp:$PATH" domain=example.com "$repo_root/.local/bin/dumpcert" >/dev/null
-
-args=$(cat "$tmp/openssl.args")
-case "$args" in
-  *'-connect example.com:443'*) ;;
-  *)
-    echo "dumpcert did not add the default HTTPS port: $args" >&2
-    exit 1
-    ;;
-esac
\ No newline at end of file
diff --git a/tests/lightcontrol-missing-value.test.sh b/tests/lightcontrol-missing-value.test.sh
new file mode 100644
index 0000000..f1be877
--- /dev/null
+++ b/tests/lightcontrol-missing-value.test.sh
@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repo_root=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)
+lightcontrol="$repo_root/.local/bin/lightcontrol"
+
+for option in -d -s; do
+  output_file=$(mktemp)
+  set +e
+  "$lightcontrol" "$option" >"$output_file" 2>&1
+  status=$?
+  set -e
+
+  if [[ $status -eq 0 ]]; then
+    echo "expected lightcontrol $option without a value to fail" >&2
+    rm -f "$output_file"
+    exit 1
+  fi
+
+  if grep -Fq 'unbound variable' "$output_file"; then
+    echo "expected usage error, got shell unbound variable for $option" >&2
+    cat "$output_file" >&2
+    rm -f "$output_file"
+    exit 1
+  fi
+
+  if ! grep -Fq 'usage lightcontrol [OPTIONS]' "$output_file"; then
+    echo "expected usage output for $option" >&2
+    cat "$output_file" >&2
+    rm -f "$output_file"
+    exit 1
+  fi
+
+  rm -f "$output_file"
+done
diff --git a/tests/local-bin-stdin.test.sh b/tests/local-bin-stdin.test.sh
deleted file mode 100755
index 383c39f..0000000
--- a/tests/local-bin-stdin.test.sh
+++ /dev/null
@@ -1,19 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-repo_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)"
-tmp_dir="$(mktemp -d)"
-cleanup() { rm -rf "$tmp_dir"; }
-trap cleanup EXIT
-
-cat >"$tmp_dir/fzf" <<'EOF'
-#!/usr/bin/env bash
-exit 0
-EOF
-chmod +x "$tmp_dir/fzf"
-
-PATH="$tmp_dir:$PATH"
-export PATH
-
-printf '{"hello":"world"}\n' | "$repo_dir/.local/bin/ljq"
-printf 'hello world\n' | "$repo_dir/.local/bin/lawk"