feat(desktop): reusable screenshot workflow for agents

AGENTS.md

@@ -224,28 +224,50 @@ See [TESTING.md](TESTING.md) for the full multi-agent E2E guide.
 
 ### Desktop Screenshots (Playwright)
 
-The desktop app is a Tauri app that cannot render in a plain browser without the
-E2E mock bridge. A standalone screenshot helper at
-`desktop/tests/helpers/screenshot.mjs` wraps the same mock bridge setup the E2E
-tests use (`addInitScript` + `window.__SPROUT_E2E__`) into a CLI tool.
+The desktop app requires the E2E mock bridge to render — it cannot run in a plain
+browser. Use `just desktop-screenshot` to capture screenshots (builds frontend,
+starts preview server, runs Playwright automatically):
 
 ```bash
-just desktop-build   # build the frontend first
-cd desktop
-node tests/helpers/screenshot.mjs --name home
-node tests/helpers/screenshot.mjs --name channel --route /channels/general
-node tests/helpers/screenshot.mjs --name search --click open-search
-node tests/helpers/screenshot.mjs --name settings --click open-settings
+just desktop-screenshot --name home
+just desktop-screenshot --name channel --route /channels/general
+just desktop-screenshot --name search --click open-search
+just desktop-screenshot --name settings --click open-settings
 ```
 
 Options: `--name` (filename), `--route` (client route), `--click` (data-testid
 or CSS selector), `--wait` (ms, default 2000), `--viewport` (WxH, default
-1280x720), `--outdir` (default `test-results/screenshots`). Screenshots are
-saved as PNGs and the path is printed to stdout.
+1280x720), `--outdir` (default `test-results/screenshots`),
+`--messages` (JSON file path). Output is a PNG path on stdout.
 
-The Playwright MCP browser (`@playwright/mcp`) is also configured but cannot
-drive the desktop app directly because it evaluates JS after page load — too
-late for the mock bridge. Use the MCP browser for non-Tauri pages only.
+Use `--messages` to inject content into a channel before capture. The JSON file
+is an array of `{ channelName, content, pubkey?, kind? }` objects — all must
+target the same channel (`[a-z0-9-]+`). When provided, `--route` is ignored.
+
+```bash
+just desktop-screenshot --name code-blocks --messages /tmp/msgs.json
+```
+
+```json
+[
+  { "channelName": "general", "content": "```typescript\nconst x = 42;\n```" },
+  { "channelName": "general", "content": "plain text message" }
+]
+```
+
+Available mock channels: `general`, `random`, `design`, `sales`, `engineering`,
+`agents`, `watercooler`, `announcements`, `alice-tyler`, `bob-tyler`.
+
+`scripts/post-screenshots.sh` hosts PNGs on a per-developer orphan branch
+(`agent-screenshots/<github-username>`) and posts a PR comment:
+
+```bash
+./scripts/post-screenshots.sh 803 test-results/screenshots
+./scripts/post-screenshots.sh 803 test-results/screenshots body.md  # custom body prepended
+```
+
+Re-runs for the same PR overwrite previous images. Cleanup:
+`git push origin --delete agent-screenshots/<username>`.
 
 ---
 

desktop/tests/helpers/screenshot.mjs

@@ -16,9 +16,10 @@
 //   --wait <ms>          Milliseconds to wait before capture (default: 2000)
 //   --viewport <WxH>     Viewport dimensions (default: 1280x720)
 //   --outdir <path>      Output directory (default: test-results/screenshots)
+//   --messages <path>    JSON file with messages to inject before capture
 
 import { parseArgs } from "node:util";
-import { existsSync, mkdirSync } from "node:fs";
+import { existsSync, mkdirSync, readFileSync } from "node:fs";
 import { resolve, join } from "node:path";
 import { chromium } from "@playwright/test";
 
@@ -30,6 +31,7 @@ const { values: args } = parseArgs({
     wait: { type: "string", default: "2000" },
     viewport: { type: "string", default: "1280x720" },
     outdir: { type: "string", default: "test-results/screenshots" },
+    messages: { type: "string" },
   },
   strict: true,
 });
@@ -110,20 +112,101 @@ await page.addInitScript(() => {
   window.__SPROUT_E2E_APP_BADGE_COUNT__ = 0;
 });
 
-const url = args.route === "/" ? BASE_URL : `${BASE_URL}/#${args.route}`;
-await page.goto(url);
-await page.waitForTimeout(waitMs);
+try {
+  if (args.messages) {
+    if (args.route !== "/") {
+      console.warn("warning: --route is ignored when --messages is provided");
+    }
 
-if (args.click) {
-  const selector = args.click.startsWith("[")
-    ? args.click
-    : `[data-testid="${args.click}"]`;
-  await page.click(selector);
-  await page.waitForTimeout(500);
-}
+    let messages;
+    try {
+      messages = JSON.parse(readFileSync(resolve(args.messages), "utf8"));
+    } catch (err) {
+      console.error(`Failed to read messages file: ${err.message}`);
+      process.exitCode = 1;
+      throw err;
+    }
+
+    if (
+      !Array.isArray(messages) ||
+      messages.length === 0 ||
+      messages.some(
+        (m) =>
+          typeof m.channelName !== "string" || typeof m.content !== "string",
+      )
+    ) {
+      const msg =
+        "messages file must be a non-empty array of { channelName: string, content: string, pubkey?: string, kind?: number }";
+      console.error(msg);
+      process.exitCode = 1;
+      throw new Error(msg);
+    }
+
+    const channels = new Set(messages.map((m) => m.channelName));
+    if (channels.size > 1) {
+      const msg =
+        "All messages must target the same channelName for a single screenshot";
+      console.error(msg);
+      process.exitCode = 1;
+      throw new Error(msg);
+    }
+
+    const channelName = messages[0].channelName;
+
+    if (!/^[a-z0-9-]+$/.test(channelName)) {
+      const msg = `Invalid channel name: ${channelName}`;
+      console.error(msg);
+      process.exitCode = 1;
+      throw new Error(msg);
+    }
+
+    await page.goto(BASE_URL);
+    await page.waitForSelector(`[data-testid="channel-${channelName}"]`, {
+      timeout: 10000,
+    });
+    await page.click(`[data-testid="channel-${channelName}"]`);
 
-const filepath = join(outdir, `${args.name}.png`);
-await page.screenshot({ path: filepath });
-console.log(filepath);
+    await page.waitForFunction(
+      (name) =>
+        window.__SPROUT_E2E_HAS_MOCK_LIVE_SUBSCRIPTION__?.({
+          channelName: name,
+        }) ?? false,
+      channelName,
+      { timeout: 10000 },
+    );
 
-await browser.close();
+    for (const msg of messages) {
+      await page.evaluate(
+        (m) => {
+          window.__SPROUT_E2E_EMIT_MOCK_MESSAGE__?.(m);
+        },
+        {
+          channelName: msg.channelName,
+          content: msg.content,
+          pubkey: msg.pubkey ?? DEFAULT_MOCK_PUBKEY,
+          kind: msg.kind,
+        },
+      );
+    }
+
+    await page.waitForTimeout(waitMs);
+  } else {
+    const url = args.route === "/" ? BASE_URL : `${BASE_URL}/#${args.route}`;
+    await page.goto(url);
+    await page.waitForTimeout(waitMs);
+  }
+
+  if (args.click) {
+    const selector = args.click.startsWith("[")
+      ? args.click
+      : `[data-testid="${args.click}"]`;
+    await page.click(selector);
+    await page.waitForTimeout(500);
+  }
+
+  const filepath = join(outdir, `${args.name}.png`);
+  await page.screenshot({ path: filepath });
+  console.log(filepath);
+} finally {
+  await browser.close();
+}

justfile

@@ -198,6 +198,19 @@ desktop-e2e-smoke:
 desktop-e2e-integration: _ensure-migrations
     cd {{desktop_dir}} && pnpm test:e2e:integration
 
+# Take desktop screenshots using the mock bridge
+desktop-screenshot *ARGS:
+    #!/usr/bin/env bash
+    set -euo pipefail
+    just desktop-build
+    cd {{desktop_dir}}
+    if ! curl -sf http://127.0.0.1:4173/ >/dev/null 2>&1; then
+        python3 -m http.server 4173 -d dist >/dev/null 2>&1 &
+        trap "kill $! 2>/dev/null || true" EXIT
+        for i in $(seq 1 20); do curl -sf http://127.0.0.1:4173/ >/dev/null && break; sleep 0.5; done
+    fi
+    node tests/helpers/screenshot.mjs {{ARGS}}
+
 # Mesh-compute e2e: the CI-safe layers (relay mesh signaling invariants + Playwright UI)
 mesh-e2e:
     cargo test -p sprout-relay mesh_signaling

scripts/post-screenshots.sh

@@ -0,0 +1,64 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+if [[ $# -lt 2 ]]; then
+  echo "Usage: $0 <pr-number> <png-dir> [comment-body-file]" >&2
+  exit 1
+fi
+
+PR="$1"
+PNG_DIR="$2"
+BODY_FILE="${3:-}"
+
+if ! [[ "$PR" =~ ^[0-9]+$ ]]; then
+  echo "error: PR number must be a positive integer" >&2
+  exit 1
+fi
+
+GH_USER=$(gh api user --jq .login)
+BRANCH="agent-screenshots/${GH_USER}"
+REPO="block/sprout"
+RAW_BASE="https://github.com/${REPO}/refs/heads/${BRANCH}"
+
+mapfile -t PNGS < <(find "$PNG_DIR" -maxdepth 1 -name "*.png" -type f | sort)
+if [[ ${#PNGS[@]} -eq 0 ]]; then
+  echo "error: no PNGs found in $PNG_DIR" >&2
+  exit 1
+fi
+
+EXISTING_ENTRIES=""
+if git fetch origin "refs/heads/${BRANCH}:refs/remotes/origin/${BRANCH}" 2>/dev/null; then
+  EXISTING_ENTRIES=$(git ls-tree "origin/${BRANCH}" | grep -v $'\t'"\"\\{0,1\\}pr-${PR}--" || true)
+fi
+
+NEW_ENTRIES=""
+IMAGE_URLS=()
+for PNG in "${PNGS[@]}"; do
+  FILENAME=$(basename "$PNG")
+  BLOB=$(git hash-object -w "$PNG")
+  TREE_PATH="pr-${PR}--${FILENAME}"
+  NEW_ENTRIES+="$(printf '100644 blob %s\t%s' "$BLOB" "$TREE_PATH")"$'\n'
+  IMAGE_URLS+=("${RAW_BASE}/${TREE_PATH}")
+done
+
+COMBINED=$(printf '%s\n' "$EXISTING_ENTRIES" "$NEW_ENTRIES" | grep -v '^$')
+TREE=$(echo "$COMBINED" | git mktree)
+
+COMMIT=$(git commit-tree "$TREE" -m "screenshots: PR #${PR}")
+git push --force-with-lease origin "${COMMIT}:refs/heads/${BRANCH}"
+
+IMAGES_SECTION=""
+for URL in "${IMAGE_URLS[@]}"; do
+  FILENAME=$(basename "$URL")
+  NAME="${FILENAME%.png}"
+  IMAGES_SECTION+="![${NAME}](${URL})"$'\n\n'
+done
+
+if [[ -n "$BODY_FILE" ]]; then
+  COMMENT_BODY="$(cat "$BODY_FILE")"$'\n\n'"${IMAGES_SECTION}"
+else
+  COMMENT_BODY="## Screenshots"$'\n\n'"${IMAGES_SECTION}"
+fi
+
+gh pr comment "$PR" --repo "$REPO" --body "$COMMENT_BODY"
+echo "Posted ${#PNGS[@]} screenshot(s) to PR #${PR}"