diff --git a/README.md b/README.md
index 5292aa04..ee3dfcf6 100644
--- a/README.md
+++ b/README.md
@@ -49,34 +49,69 @@ Instead, you can make use of this GitHub Action from the comfort of your own rep
 1. [Create a Twitter app](docs/01-create-twitter-app.md) with your shared Twitter account and store the credentials as `TWITTER_API_KEY`, `TWITTER_API_SECRET_KEY`, `TWITTER_ACCESS_TOKEN` and `TWITTER_ACCESS_TOKEN_SECRET` in your repository’s secrets settings.
 2. [Create a `.github/workflows/twitter-together.yml` file](docs/02-create-twitter-together-workflow.md) with the content below. Make sure to replace `'main'` if you changed your repository's default branch.
 
-   ```yml
-   on: [push, pull_request]
-   name: Twitter, together!
-   jobs:
-     preview:
-       name: Preview
-       runs-on: ubuntu-latest
-       if: github.event_name == 'pull_request'
-       steps:
-         - uses: twitter-together/action@v2
-           env:
-             GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-     tweet:
-       name: Tweet
-       runs-on: ubuntu-latest
-       if: github.event_name == 'push' && github.ref == 'refs/heads/main'
-       steps:
-         - name: checkout main
-           uses: actions/checkout@v3
-         - name: Tweet
-           uses: twitter-together/action@v2
-           env:
-             GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-             TWITTER_ACCESS_TOKEN: ${{ secrets.TWITTER_ACCESS_TOKEN }}
-             TWITTER_ACCESS_TOKEN_SECRET: ${{ secrets.TWITTER_ACCESS_TOKEN_SECRET }}
-             TWITTER_API_KEY: ${{ secrets.TWITTER_API_KEY }}
-             TWITTER_API_SECRET_KEY: ${{ secrets.TWITTER_API_SECRET_KEY }}
-   ```
+```yml
+on: [push, pull_request]
+name: Twitter, together!
+jobs:
+  preview:
+    name: Preview
+    runs-on: ubuntu-latest
+    if: github.event_name == 'pull_request'
+    steps:
+      - name: checkout pull request
+        uses: actions/checkout@v3
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Validate Tweets
+        uses: twitter-together/action@v3
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+  tweet:
+    name: Tweet
+    runs-on: ubuntu-latest
+    if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+    steps:
+      - name: checkout main
+        uses: actions/checkout@v3
+      - name: Tweet
+        uses: twitter-together/action@v3
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          TWITTER_ACCESS_TOKEN: ${{ secrets.TWITTER_ACCESS_TOKEN }}
+          TWITTER_ACCESS_TOKEN_SECRET: ${{ secrets.TWITTER_ACCESS_TOKEN_SECRET }}
+          TWITTER_API_KEY: ${{ secrets.TWITTER_API_KEY }}
+          TWITTER_API_SECRET_KEY: ${{ secrets.TWITTER_API_SECRET_KEY }}
+```
+
+TODO: CONFIRM
+
+If you wish to have this action create preview comments in the PR thread, you can use the following config.
+
+Note that `pull_request_target` events have elevated permissions, so if you are using this config, you should configure your repository to only trigger actions that are trusted. You can do this in [various](https://securitylab.github.com/research/github-actions-preventing-pwn-requests/) ways, including preventing outside contributors from triggering actions automatically, and requiring only allowing actions from Verified Creators in your repository Settings -> Actions -> General.
+
+You can also securely enable PR comments only for local branch commits, using the `pull_request` events with an `ENABLE_COMMENTS: 1` env variable, but comments will not be created for PRs from forks.
+
+```yml
+# enable comments, but beware of security implications
+on: [push, pull_request_target]
+name: Twitter, together!
+jobs:
+  preview:
+    name: Preview
+    runs-on: ubuntu-latest
+    if: github.event_name == 'pull_request_target'
+    permissions:
+      pull-requests: write
+    steps:
+      - name: checkout pull request
+        uses: actions/checkout@v3
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Validate Tweets
+        uses: twitter-together/action@v3
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+```
 
 3. After creating or updating `.github/workflows/twitter-together.yml` in your repository’s default branch, a pull request will be created with further instructions.
 
diff --git a/docs/02-create-twitter-together-workflow.md b/docs/02-create-twitter-together-workflow.md
index 5bf5662e..275bd0d5 100644
--- a/docs/02-create-twitter-together-workflow.md
+++ b/docs/02-create-twitter-together-workflow.md
@@ -21,7 +21,12 @@ jobs:
     runs-on: ubuntu-latest
     if: github.event_name == 'pull_request'
     steps:
-      - uses: twitter-together/action@v2
+      - name: checkout pull request
+        uses: actions/checkout@v3
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Validate Tweets
+        uses: twitter-together/action@v2
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
   tweet:
diff --git a/lib/common/parse-tweet-file-content.js b/lib/common/parse-tweet-file-content.js
index 77b1f885..45eb0492 100644
--- a/lib/common/parse-tweet-file-content.js
+++ b/lib/common/parse-tweet-file-content.js
@@ -6,6 +6,7 @@ const { existsSync } = require("fs");
 const { join } = require("path");
 const { parseTweet } = require("twitter-text");
 const { load } = require("js-yaml");
+const parseTweetId = require("./parse-tweet-id");
 
 const OPTION_REGEX = /^\(\s?\)\s+/;
 const FRONT_MATTER_REGEX = new RegExp(
@@ -87,6 +88,9 @@ function parseTweetFileContent(text, dir, isThread = false) {
 }
 
 function validateOptions(options, text, dir) {
+  if (options.retweet || options.reply)
+    parseTweetId(options.retweet || options.reply);
+
   if (options.retweet && !text && options.poll)
     throw new Error("Cannot attach a poll to a retweet");
 
diff --git a/lib/common/parse-tweet-id.js b/lib/common/parse-tweet-id.js
new file mode 100644
index 00000000..d33f4e41
--- /dev/null
+++ b/lib/common/parse-tweet-id.js
@@ -0,0 +1,16 @@
+module.exports = parseTweetId;
+
+const TWEET_REGEX = /^https:\/\/twitter\.com\/[^/]+\/status\/(\d+)$/;
+
+// TODO allow differently formatted URLs and tweet ids ?
+// https://github.com/twitter-together/action/issues/221
+
+// TODO: Should we check if the referenced tweet actually exists?
+
+function parseTweetId(tweetRef) {
+  const match = tweetRef.match(TWEET_REGEX);
+  if (!match) {
+    throw new Error(`Invalid tweet reference: ${tweetRef}`);
+  }
+  return match[1];
+}
diff --git a/lib/common/tweet.js b/lib/common/tweet.js
index 37103fd2..7e6ea284 100644
--- a/lib/common/tweet.js
+++ b/lib/common/tweet.js
@@ -3,7 +3,7 @@ module.exports = tweet;
 const { TwitterApi } = require("twitter-api-v2");
 const mime = require("mime-types");
 
-const TWEET_REGEX = /^https:\/\/twitter\.com\/[^/]+\/status\/(\d+)$/;
+const parseTweetId = require("./parse-tweet-id");
 
 async function tweet({ twitterCredentials }, tweetData, tweetFile) {
   const client = new TwitterApi(twitterCredentials);
@@ -16,9 +16,8 @@ async function tweet({ twitterCredentials }, tweetData, tweetFile) {
 
 async function handleTweet(client, self, tweet, name) {
   if (tweet.retweet && !tweet.text) {
-    // TODO: Should this throw if an invalid tweet is passed and there is no match?
-    const match = tweet.retweet.match(TWEET_REGEX);
-    if (match) return createRetweet(client, self, match[1]);
+    const tweetId = parseTweetId(tweet.retweet);
+    if (tweetId) return createRetweet(client, self, tweetId);
   }
 
   const tweetData = {
@@ -33,19 +32,17 @@ async function handleTweet(client, self, tweet, name) {
   }
 
   if (tweet.reply) {
-    // TODO: Should this throw if an invalid reply is passed and there is no match?
-    const match = tweet.reply.match(TWEET_REGEX);
-    if (match) {
+    const tweetId = parseTweetId(tweet.reply);
+    if (tweetId) {
       tweetData.reply = {
-        in_reply_to_tweet_id: match[1],
+        in_reply_to_tweet_id: tweetId,
       };
     }
   }
 
   if (tweet.retweet) {
-    // TODO: Should this throw if an invalid tweet is passed and there is no match?
-    const match = tweet.retweet.match(TWEET_REGEX);
-    if (match) tweetData.quote_tweet_id = match[1];
+    const tweetId = parseTweetId(tweet.retweet);
+    if (tweetId) tweetData.quote_tweet_id = tweetId;
   }
 
   if (tweet.media?.length) {
diff --git a/lib/index.js b/lib/index.js
index 0350c77b..550c7bae 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -46,6 +46,10 @@ async function main() {
   const ref = process.env.GITHUB_REF;
   const sha = process.env.GITHUB_SHA;
   const dir = process.env.GITHUB_WORKSPACE;
+  const trigger = process.env.GITHUB_EVENT_NAME;
+  // optionally allow enabling comments them on "pull_request" for local branches
+  const enableComments = !!process.env.ENABLE_COMMENTS;
+
   const githubState = {
     ...state,
     toolkit,
@@ -54,15 +58,15 @@ async function main() {
     ref,
     sha,
     dir,
+    trigger,
+    enableComments,
   };
 
-  switch (process.env.GITHUB_EVENT_NAME) {
-    case "push":
-      await handlePush(githubState);
-      break;
-    case "pull_request":
-      await handlePullRequest(githubState);
-      break;
+  if (trigger === "push") {
+    await handlePush(githubState);
+  }
+  if (trigger === "pull_request" || trigger === "pull_request_target") {
+    await handlePullRequest(githubState);
   }
 }
 
diff --git a/lib/pull-request/create-check-run.js b/lib/pull-request/create-check-run.js
index 966c4182..53086927 100644
--- a/lib/pull-request/create-check-run.js
+++ b/lib/pull-request/create-check-run.js
@@ -1,49 +1,12 @@
 module.exports = createCheckRun;
 
-const { autoLink } = require("twitter-text");
-
-const parseTweetFileContent = require("../common/parse-tweet-file-content");
-
 async function createCheckRun(
-  { octokit, payload, startedAt, toolkit, dir },
-  newTweets
+  { payload, startedAt, octokit, toolkit },
+  summary
 ) {
-  const parsedTweets = newTweets.map((rawTweet) => {
-    try {
-      return parseTweetFileContent(rawTweet, dir);
-    } catch (error) {
-      return {
-        error: error.message,
-        valid: false,
-        text: rawTweet,
-      };
-    }
-  });
-
-  const allTweetsValid = parsedTweets.every((tweet) => tweet.valid);
-
-  // Check runs cannot be created if the pull request was created by a fork,
-  // so we just log out the result.
-  // https://help.github.com/en/actions/automating-your-workflow-with-github-actions/authenticating-with-the-github_token#permissions-for-the-github_token
-  if (payload.pull_request.head.repo.fork) {
-    for (const tweet of parsedTweets) {
-      if (tweet.valid) {
-        toolkit.info(`### ✅ Valid\n\n${tweet.text}`);
-      } else {
-        toolkit.info(
-          `### ❌ Invalid\n\n${tweet.text}\n\n${tweet.error || "Unknown error"}`
-        );
-      }
-    }
-    process.exit(allTweetsValid ? 0 : 1);
-  }
-
   const response = await octokit.request(
     "POST /repos/:owner/:repo/check-runs",
     {
-      headers: {
-        accept: "application/vnd.github.antiope-preview+json",
-      },
       owner: payload.repository.owner.login,
       repo: payload.repository.name,
       name: "preview",
@@ -51,27 +14,12 @@ async function createCheckRun(
       started_at: startedAt,
       completed_at: new Date().toISOString(),
       status: "completed",
-      conclusion: allTweetsValid ? "success" : "failure",
+      conclusion: summary.valid ? "success" : "failure",
       output: {
-        title: `${parsedTweets.length} tweet(s)`,
-        summary: parsedTweets.map(tweetToCheckRunSummary).join("\n\n---\n\n"),
+        title: `${summary.count} tweet(s)`,
+        summary: summary.body,
       },
     }
   );
-
   toolkit.info(`check run created: ${response.data.html_url}`);
 }
-
-function tweetToCheckRunSummary(tweet) {
-  let text = autoLink(tweet.text)
-    .replace(/(^|\n)/g, "$1> ")
-    .replace(/(^|\n)> (\n|$)/g, "$1>$2");
-
-  if (!tweet.valid)
-    return `### ❌ Invalid\n\n${text}\n\n${tweet.error || "Unknown error"}`;
-
-  if (tweet.poll)
-    text +=
-      "\n\nThe tweet includes a poll:\n\n> 🔘 " + tweet.poll.join("\n> 🔘 ");
-  return `### ✅ Valid\n\n${text}`;
-}
diff --git a/lib/pull-request/create-comment.js b/lib/pull-request/create-comment.js
new file mode 100644
index 00000000..2949b9c6
--- /dev/null
+++ b/lib/pull-request/create-comment.js
@@ -0,0 +1,50 @@
+module.exports = createComment;
+
+const BOT_LOGIN = "github-actions[bot]";
+
+const DIVIDER = "\n\n---\n\n*";
+const PREVIEW = `${DIVIDER}Preview using `;
+const UPDATED = `${DIVIDER}**Updated** preview using `;
+const SIGNATURE =
+  " generated by [Twitter, together!](https://github.com/twitter-together/action)*";
+
+async function createComment({ octokit, payload }, summary) {
+  const comment = `${summary.title}${summary.body}`;
+  // check for existing comments.
+  const comments = await octokit.request(
+    "GET /repos/{owner}/{repo}/issues/{issue_number}/comments",
+    {
+      owner: payload.repository.owner.login,
+      repo: payload.repository.name,
+      issue_number: payload.pull_request.number,
+    }
+  );
+
+  const match = comments.data.find(
+    ({ user, body }) => user.login === BOT_LOGIN && body.endsWith(SIGNATURE)
+  );
+
+  if (match) {
+    // update the existing comment
+    await octokit.request(
+      "PATCH /repos/{owner}/{repo}/issues/comments/{comment_id}",
+      {
+        owner: payload.repository.owner.login,
+        repo: payload.repository.name,
+        comment_id: match.id,
+        body: `${comment}${UPDATED}${payload.pull_request.head.sha}${SIGNATURE}`,
+      }
+    );
+  } else {
+    // post a new comment
+    await octokit.request(
+      "POST /repos/{owner}/{repo}/issues/{issue_number}/comments",
+      {
+        owner: payload.repository.owner.login,
+        repo: payload.repository.name,
+        issue_number: payload.pull_request.number,
+        body: `${comment}${PREVIEW}${payload.pull_request.head.sha}${SIGNATURE}`,
+      }
+    );
+  }
+}
diff --git a/lib/pull-request/generate-summary.js b/lib/pull-request/generate-summary.js
new file mode 100644
index 00000000..f50bcc8e
--- /dev/null
+++ b/lib/pull-request/generate-summary.js
@@ -0,0 +1,81 @@
+module.exports = generateSummary;
+
+const { autoLink } = require("twitter-text");
+
+const parseTweetFileContent = require("../common/parse-tweet-file-content");
+const getNewTweets = require("./get-new-tweets");
+
+async function generateSummary(state, plainText = false) {
+  const { payload, dir } = state;
+
+  const newTweets = await getNewTweets(state);
+
+  const parsedTweets = newTweets.map((tweet) => {
+    try {
+      return parseTweetFileContent(tweet, dir);
+    } catch (error) {
+      return {
+        error: error.message,
+        valid: false,
+        text: tweet,
+      };
+    }
+  });
+
+  return {
+    count: parsedTweets.length,
+    valid: parsedTweets.every((tweet) => tweet.valid),
+    title: `## Found ${parsedTweets.length} new \`.tweet\` file(s)\n\n`,
+    body: parsedTweets
+      .map((tweet) => summarizeTweet({ tweet, payload, dir, plainText }))
+      .join("\n\n---\n\n"),
+  };
+}
+
+function summarizeTweet(state, threading = false) {
+  const { tweet, payload, dir, plainText } = state;
+
+  if (!tweet.valid)
+    return `### ❌ Invalid Tweet\n\n\`\`\`tweet\n${tweet.text}\n\`\`\`\n\n**${
+      tweet.error || "Unknown error"
+    }**`;
+
+  let text = !tweet.text
+    ? ""
+    : autoLink(tweet.text)
+        .replace(/(^|\n)/g, "$1> ")
+        .replace(/(^|\n)> (\n|$)/g, "$1>$2");
+
+  if (tweet.poll) text = `- ${tweet.poll.join("\n- ")}\n\n${text}`;
+
+  if (tweet.reply) text = `Replying to ${tweet.reply}\n\n${text}`;
+
+  if (tweet.retweet) text = `Retweeting ${tweet.retweet}\n\n${text}`.trim();
+
+  if (tweet.media.length) {
+    const media = tweet.media
+      .map(({ file, alt }) => {
+        const fileName = file.replace(dir, "");
+        if (plainText) {
+          return `- ${fileName}${alt && ` [${alt}]`}`;
+        } else {
+          const { repo, sha } = payload.pull_request.head;
+          return `${alt || ""}\n<img src="https://raw.githubusercontent.com/${
+            repo.owner.login
+          }/${repo.name}/${sha}${fileName}" height="200" />`;
+        }
+      })
+      .join(plainText ? "\n" : "\n\n");
+    text = `${media}\n\n${text}`.trim();
+  }
+
+  if (tweet.thread || threading) {
+    const count = threading ? threading + 1 : 1;
+    let thread = `\n\n#### --- 🧵 ${count} ---\n\n${text}`;
+    if (tweet.thread)
+      thread += summarizeTweet({ ...state, tweet: tweet.thread }, count);
+    return threading ? thread : `### ✅ Valid Thread${thread}`;
+  }
+
+  return `### ✅ Valid Tweet\n\n${text}`;
+}
diff --git a/lib/pull-request/index.js b/lib/pull-request/index.js
index 14eb5f14..f10070f1 100644
--- a/lib/pull-request/index.js
+++ b/lib/pull-request/index.js
@@ -1,14 +1,21 @@
 module.exports = handlePullRequest;
 
-const getNewTweets = require("./get-new-tweets");
 const createCheckRun = require("./create-check-run");
+const createComment = require("./create-comment");
+const generateSummary = require("./generate-summary");
+
+const CHECK = "check";
+const LOG = "log";
+const COMMENT = "comment";
 
 async function handlePullRequest(state) {
-  const { octokit, toolkit, payload } = state;
+  const { octokit, toolkit, payload, trigger, enableComments } = state;
 
-  // ignore builds from branches other than the repository’s defaul branch
+  // ignore builds from branches other than the repository’s default branch
   const base = payload.pull_request.base.ref;
   const defaultBranch = payload.repository.default_branch;
+  const fork = !!payload.pull_request.head.repo.fork;
+
   if (defaultBranch !== base) {
     return toolkit.info(
       `Pull request base "${base}" is not the repository’s default branch`
@@ -22,6 +29,29 @@ async function handlePullRequest(state) {
     process.exit();
   });
 
-  const newTweets = await getNewTweets(state);
-  await createCheckRun(state, newTweets);
+  // default report type, for `pull_request` non-fork PRs
+  let reportType = CHECK;
+  // can only log the output for fork PRs without check run permissions
+  if (fork && trigger === "pull_request") {
+    reportType = LOG;
+  }
+  // assume use of comments for `pull_request_target` PRs
+  // optional: use comments instead of check runs for `pull_request`
+  if (trigger === "pull_request_target" || enableComments) {
+    reportType = COMMENT;
+  }
+
+  const summary = await generateSummary(state, reportType === LOG);
+
+  if (reportType === LOG) {
+    toolkit.info(summary.body);
+    process.exit(summary.valid ? 0 : 1);
+  }
+  if (reportType === COMMENT) {
+    await createComment(state, summary);
+    process.exit(summary.valid ? 0 : 1);
+  }
+  if (reportType === CHECK) {
+    await createCheckRun(state, summary);
+  }
 }
diff --git a/test/pull-request-has-tweet-issue-comment-updated/event.json b/test/pull-request-has-tweet-issue-comment-updated/event.json
new file mode 100644
index 00000000..ad692d8e
--- /dev/null
+++ b/test/pull-request-has-tweet-issue-comment-updated/event.json
@@ -0,0 +1,22 @@
+{
+  "action": "opened",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000002",
+      "repo": {
+        "fork": false
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-has-tweet-issue-comment-updated/test.js b/test/pull-request-has-tweet-issue-comment-updated/test.js
new file mode 100644
index 00000000..4767872e
--- /dev/null
+++ b/test/pull-request-has-tweet-issue-comment-updated/test.js
@@ -0,0 +1,116 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = "";
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+process.env.ENABLE_COMMENTS = "1";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/tweets/hello-world.tweet b/tweets/hello-world.tweet
+new file mode 100644
+index 0000000..0123456
+--- /dev/null
++++ b/tweets/hello-world.tweet
+@@ -0,0 +1 @@
++Hello, world!`
+  );
+
+// check for comments
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // has a comment
+  .get("/repos/twitter-together/action/issues/123/comments")
+  .reply(200, [
+    {
+      id: 454,
+      user: { login: "some-other-account" },
+      body: "blah",
+    },
+    {
+      id: 455,
+      user: { login: "github-actions[bot]" },
+      body: "A comment generated by some other action",
+    },
+    {
+      id: 456,
+      user: { login: "github-actions[bot]" },
+      body: `## Found 1 new \`.tweet\` file(s)
+
+### ✅ Valid Tweet
+
+> Hello, world!
+
+---
+
+*Preview using 0000000000000000000000000000000000000002 generated by [Twitter, together!](https://github.com/twitter-together/action)*`,
+    },
+  ]);
+
+// update comment
+nock("https://api.github.com")
+  // get changed files
+  .patch("/repos/twitter-together/action/issues/comments/456", ({ body }) => {
+    tap.same(
+      body,
+      `## Found 1 new \`.tweet\` file(s)
+
+### ✅ Valid Tweet
+
+> Hello, world!
+
+---
+
+***Updated** preview using 0000000000000000000000000000000000000002 generated by [Twitter, together!](https://github.com/twitter-together/action)*`
+    );
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/pull-request-has-tweet-issue-comment/event.json b/test/pull-request-has-tweet-issue-comment/event.json
new file mode 100644
index 00000000..ad692d8e
--- /dev/null
+++ b/test/pull-request-has-tweet-issue-comment/event.json
@@ -0,0 +1,22 @@
+{
+  "action": "opened",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000002",
+      "repo": {
+        "fork": false
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-has-tweet-issue-comment/test.js b/test/pull-request-has-tweet-issue-comment/test.js
new file mode 100644
index 00000000..f4592abe
--- /dev/null
+++ b/test/pull-request-has-tweet-issue-comment/test.js
@@ -0,0 +1,92 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = "";
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+process.env.ENABLE_COMMENTS = "1";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/tweets/hello-world.tweet b/tweets/hello-world.tweet
+new file mode 100644
+index 0000000..0123456
+--- /dev/null
++++ b/tweets/hello-world.tweet
+@@ -0,0 +1 @@
++Hello, world!`
+  );
+
+// check for comments
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // no comments
+  .get("/repos/twitter-together/action/issues/123/comments")
+  .reply(200, []);
+
+// post comment
+nock("https://api.github.com")
+  // get changed files
+  .post("/repos/twitter-together/action/issues/123/comments", ({ body }) => {
+    tap.same(
+      body,
+      `## Found 1 new \`.tweet\` file(s)
+
+### ✅ Valid Tweet
+
+> Hello, world!
+
+---
+
+*Preview using 0000000000000000000000000000000000000002 generated by [Twitter, together!](https://github.com/twitter-together/action)*`
+    );
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/pull-request-has-tweet-no-newline/test.js b/test/pull-request-has-tweet-no-newline/test.js
index 864069ce..8c5c37da 100644
--- a/test/pull-request-has-tweet-no-newline/test.js
+++ b/test/pull-request-has-tweet-no-newline/test.js
@@ -65,7 +65,7 @@ nock("https://api.github.com")
     tap.equal(body.conclusion, "success");
     tap.same(body.output, {
       title: "1 tweet(s)",
-      summary: "### ✅ Valid\n\n> Hello, world!",
+      summary: "### ✅ Valid Tweet\n\n> Hello, world!",
     });
 
     return true;
diff --git a/test/pull-request-has-tweet-with-front-matter-media/event.json b/test/pull-request-has-tweet-with-front-matter-media/event.json
new file mode 100644
index 00000000..6eb7c183
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-media/event.json
@@ -0,0 +1,27 @@
+{
+  "action": "opened",
+  "after": "0000000000000000000000000000000000000003",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000003",
+      "repo": {
+        "name": "action",
+        "fork": false,
+        "owner": {
+          "login": "twitter-together"
+        }
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-has-tweet-with-front-matter-media/media/cat.jpg b/test/pull-request-has-tweet-with-front-matter-media/media/cat.jpg
new file mode 100644
index 00000000..a10d5059
Binary files /dev/null and b/test/pull-request-has-tweet-with-front-matter-media/media/cat.jpg differ
diff --git a/test/pull-request-has-tweet-with-front-matter-media/media/nested/media/pets/dog.jpg b/test/pull-request-has-tweet-with-front-matter-media/media/nested/media/pets/dog.jpg
new file mode 100644
index 00000000..7a25bfbe
Binary files /dev/null and b/test/pull-request-has-tweet-with-front-matter-media/media/nested/media/pets/dog.jpg differ
diff --git a/test/pull-request-has-tweet-with-front-matter-media/test.js b/test/pull-request-has-tweet-with-front-matter-media/test.js
new file mode 100644
index 00000000..d77cbffb
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-media/test.js
@@ -0,0 +1,101 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+const path = require("path");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = path.dirname(process.env.GITHUB_EVENT_PATH);
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/media/cat.jpg b/media/cat.jpg
+new file mode 100644
+index 0000000..a10d505
+Binary files /dev/null and b/media/cat.jpg differ
+diff --git a/media/dog.jpg b/media/dog.jpg
+new file mode 100644
+index 0000000..7a25bfb
+Binary files /dev/null and b/media/dog.jpg differ
+diff --git a/tweets/media.tweet b/tweets/media.tweet
+new file mode 100644
+index 0000000..1715c04
+--- /dev/null
++++ b/tweets/media.tweet
+@@ -0,0 +1,9 @@
++---
++media:
++  - file: cat.jpg
++  - file: nested/media/pets/dog.jpg
++    alt: A dog
++---
++
++Here are some cute animals!`
+  );
+
+// create check run
+nock("https://api.github.com")
+  // get changed files
+  .post("/repos/twitter-together/action/check-runs", (body) => {
+    tap.equal(body.name, "preview");
+    tap.equal(body.head_sha, "0000000000000000000000000000000000000003");
+    tap.equal(body.status, "completed");
+    tap.equal(body.conclusion, "success");
+    tap.same(body.output, {
+      title: "1 tweet(s)",
+      summary: `### ✅ Valid Tweet
+
+<img src="https://raw.githubusercontent.com/twitter-together/action/0000000000000000000000000000000000000003/media/cat.jpg" height="200" />
+
+A dog
+<img src="https://raw.githubusercontent.com/twitter-together/action/0000000000000000000000000000000000000003/media/nested/media/pets/dog.jpg" height="200" />
+
+> Here are some cute animals!`,
+    });
+
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/pull-request-has-tweet-with-front-matter-poll-5-options/event.json b/test/pull-request-has-tweet-with-front-matter-poll-5-options/event.json
new file mode 100644
index 00000000..ad692d8e
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-poll-5-options/event.json
@@ -0,0 +1,22 @@
+{
+  "action": "opened",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000002",
+      "repo": {
+        "fork": false
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-has-tweet-with-front-matter-poll-5-options/test.js b/test/pull-request-has-tweet-with-front-matter-poll-5-options/test.js
new file mode 100644
index 00000000..d65c9a4b
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-poll-5-options/test.js
@@ -0,0 +1,102 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = "";
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/tweets/poll.tweet b/tweets/poll.tweet
+new file mode 100644
+index 0000000..6053708
+--- /dev/null
++++ b/tweets/poll.tweet
+@@ -0,0 +1,10 @@
++---
++poll:
++  - Red
++  - Blue
++  - Green
++  - Orange
++  - Purple
++---
++
++What is your favorite color?`
+  );
+
+// create check run
+nock("https://api.github.com")
+  // get changed files
+  .post("/repos/twitter-together/action/check-runs", (body) => {
+    tap.equal(body.name, "preview");
+    tap.equal(body.head_sha, "0000000000000000000000000000000000000002");
+    tap.equal(body.status, "completed");
+    tap.equal(body.conclusion, "failure");
+    tap.same(body.output, {
+      title: "1 tweet(s)",
+      summary: `### ❌ Invalid Tweet
+
+\`\`\`tweet
+---
+poll:
+  - Red
+  - Blue
+  - Green
+  - Orange
+  - Purple
+---
+
+What is your favorite color?
+\`\`\`
+
+**Polls cannot have more than four options, found 5 options**`,
+    });
+
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/pull-request-has-tweet-with-front-matter-poll/event.json b/test/pull-request-has-tweet-with-front-matter-poll/event.json
new file mode 100644
index 00000000..ad692d8e
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-poll/event.json
@@ -0,0 +1,22 @@
+{
+  "action": "opened",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000002",
+      "repo": {
+        "fork": false
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-has-tweet-with-front-matter-poll/test.js b/test/pull-request-has-tweet-with-front-matter-poll/test.js
new file mode 100644
index 00000000..8ab77e31
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-poll/test.js
@@ -0,0 +1,91 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = "";
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/tweets/poll.tweet b/tweets/poll.tweet
+new file mode 100644
+index 0000000..6053708
+--- /dev/null
++++ b/tweets/poll.tweet
+@@ -0,0 +1,8 @@
++---
++poll:
++  - Red
++  - Blue
++  - Green
++---
++
++What is your favorite color?`
+  );
+
+// create check run
+nock("https://api.github.com")
+  // get changed files
+  .post("/repos/twitter-together/action/check-runs", (body) => {
+    tap.equal(body.name, "preview");
+    tap.equal(body.head_sha, "0000000000000000000000000000000000000002");
+    tap.equal(body.status, "completed");
+    tap.equal(body.conclusion, "success");
+    tap.same(body.output, {
+      title: "1 tweet(s)",
+      summary: `### ✅ Valid Tweet
+
+- Red
+- Blue
+- Green
+
+> What is your favorite color?`,
+    });
+
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/pull-request-has-tweet-with-front-matter-quote/event.json b/test/pull-request-has-tweet-with-front-matter-quote/event.json
new file mode 100644
index 00000000..ad692d8e
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-quote/event.json
@@ -0,0 +1,22 @@
+{
+  "action": "opened",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000002",
+      "repo": {
+        "fork": false
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-has-tweet-with-front-matter-quote/test.js b/test/pull-request-has-tweet-with-front-matter-quote/test.js
new file mode 100644
index 00000000..e6594ac3
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-quote/test.js
@@ -0,0 +1,86 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = "";
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/tweets/retweet.tweet b/tweets/retweet.tweet
+new file mode 100644
+index 0000000..d462a1f
+--- /dev/null
++++ b/tweets/retweet.tweet
+@@ -0,0 +1,5 @@
++---
++retweet: https://twitter.com/m2rg/status/0000000000000000001
++---
++
++Smart thinking!`
+  );
+
+// create check run
+nock("https://api.github.com")
+  // get changed files
+  .post("/repos/twitter-together/action/check-runs", (body) => {
+    tap.equal(body.name, "preview");
+    tap.equal(body.head_sha, "0000000000000000000000000000000000000002");
+    tap.equal(body.status, "completed");
+    tap.equal(body.conclusion, "success");
+    tap.same(body.output, {
+      title: "1 tweet(s)",
+      summary: `### ✅ Valid Tweet
+
+Retweeting https://twitter.com/m2rg/status/0000000000000000001
+
+> Smart thinking!`,
+    });
+
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/pull-request-has-tweet-with-front-matter-reply-invalid/event.json b/test/pull-request-has-tweet-with-front-matter-reply-invalid/event.json
new file mode 100644
index 00000000..ad692d8e
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-reply-invalid/event.json
@@ -0,0 +1,22 @@
+{
+  "action": "opened",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000002",
+      "repo": {
+        "fork": false
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-has-tweet-with-front-matter-reply-invalid/test.js b/test/pull-request-has-tweet-with-front-matter-reply-invalid/test.js
new file mode 100644
index 00000000..7c61e21c
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-reply-invalid/test.js
@@ -0,0 +1,88 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = "";
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/tweets/reply.tweet b/tweets/reply.tweet
+new file mode 100644
+index 0000000..d462a1f
+--- /dev/null
++++ b/tweets/reply.tweet
+@@ -0,0 +1,3 @@
++---
++reply: spoons
++---`
+  );
+
+// create check run
+nock("https://api.github.com")
+  // get changed files
+  .post("/repos/twitter-together/action/check-runs", (body) => {
+    tap.equal(body.name, "preview");
+    tap.equal(body.head_sha, "0000000000000000000000000000000000000002");
+    tap.equal(body.status, "completed");
+    tap.equal(body.conclusion, "failure");
+    tap.same(body.output, {
+      title: "1 tweet(s)",
+      summary: `### ❌ Invalid Tweet
+
+\`\`\`tweet
+---
+reply: spoons
+---
+\`\`\`
+
+**Invalid tweet reference: spoons**`,
+    });
+
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/pull-request-has-tweet-with-front-matter-reply/event.json b/test/pull-request-has-tweet-with-front-matter-reply/event.json
new file mode 100644
index 00000000..ad692d8e
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-reply/event.json
@@ -0,0 +1,22 @@
+{
+  "action": "opened",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000002",
+      "repo": {
+        "fork": false
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-has-tweet-with-front-matter-reply/test.js b/test/pull-request-has-tweet-with-front-matter-reply/test.js
new file mode 100644
index 00000000..f3c86c2e
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-reply/test.js
@@ -0,0 +1,86 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = "";
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/tweets/retweet.tweet b/tweets/retweet.tweet
+new file mode 100644
+index 0000000..d462a1f
+--- /dev/null
++++ b/tweets/retweet.tweet
+@@ -0,0 +1,5 @@
++---
++reply: https://twitter.com/m2rg/status/0000000000000000001
++---
++
++Good idea :)`
+  );
+
+// create check run
+nock("https://api.github.com")
+  // get changed files
+  .post("/repos/twitter-together/action/check-runs", (body) => {
+    tap.equal(body.name, "preview");
+    tap.equal(body.head_sha, "0000000000000000000000000000000000000002");
+    tap.equal(body.status, "completed");
+    tap.equal(body.conclusion, "success");
+    tap.same(body.output, {
+      title: "1 tweet(s)",
+      summary: `### ✅ Valid Tweet
+
+Replying to https://twitter.com/m2rg/status/0000000000000000001
+
+> Good idea :)`,
+    });
+
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/pull-request-has-tweet-with-front-matter-retweet-invalid/event.json b/test/pull-request-has-tweet-with-front-matter-retweet-invalid/event.json
new file mode 100644
index 00000000..ad692d8e
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-retweet-invalid/event.json
@@ -0,0 +1,22 @@
+{
+  "action": "opened",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000002",
+      "repo": {
+        "fork": false
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-has-tweet-with-front-matter-retweet-invalid/test.js b/test/pull-request-has-tweet-with-front-matter-retweet-invalid/test.js
new file mode 100644
index 00000000..8e07169e
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-retweet-invalid/test.js
@@ -0,0 +1,88 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = "";
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/tweets/retweet.tweet b/tweets/retweet.tweet
+new file mode 100644
+index 0000000..d462a1f
+--- /dev/null
++++ b/tweets/retweet.tweet
+@@ -0,0 +1,3 @@
++---
++retweet: spoons
++---`
+  );
+
+// create check run
+nock("https://api.github.com")
+  // get changed files
+  .post("/repos/twitter-together/action/check-runs", (body) => {
+    tap.equal(body.name, "preview");
+    tap.equal(body.head_sha, "0000000000000000000000000000000000000002");
+    tap.equal(body.status, "completed");
+    tap.equal(body.conclusion, "failure");
+    tap.same(body.output, {
+      title: "1 tweet(s)",
+      summary: `### ❌ Invalid Tweet
+
+\`\`\`tweet
+---
+retweet: spoons
+---
+\`\`\`
+
+**Invalid tweet reference: spoons**`,
+    });
+
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/pull-request-has-tweet-with-front-matter-retweet/event.json b/test/pull-request-has-tweet-with-front-matter-retweet/event.json
new file mode 100644
index 00000000..ad692d8e
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-retweet/event.json
@@ -0,0 +1,22 @@
+{
+  "action": "opened",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000002",
+      "repo": {
+        "fork": false
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-has-tweet-with-front-matter-retweet/test.js b/test/pull-request-has-tweet-with-front-matter-retweet/test.js
new file mode 100644
index 00000000..ea257f45
--- /dev/null
+++ b/test/pull-request-has-tweet-with-front-matter-retweet/test.js
@@ -0,0 +1,82 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = "";
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/tweets/retweet.tweet b/tweets/retweet.tweet
+new file mode 100644
+index 0000000..d462a1f
+--- /dev/null
++++ b/tweets/retweet.tweet
+@@ -0,0 +1,3 @@
++---
++retweet: https://twitter.com/m2rg/status/0000000000000000001
++---`
+  );
+
+// create check run
+nock("https://api.github.com")
+  // get changed files
+  .post("/repos/twitter-together/action/check-runs", (body) => {
+    tap.equal(body.name, "preview");
+    tap.equal(body.head_sha, "0000000000000000000000000000000000000002");
+    tap.equal(body.status, "completed");
+    tap.equal(body.conclusion, "success");
+    tap.same(body.output, {
+      title: "1 tweet(s)",
+      summary: `### ✅ Valid Tweet
+
+Retweeting https://twitter.com/m2rg/status/0000000000000000001`,
+    });
+
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/pull-request-has-tweet-with-poll-with-5-options/test.js b/test/pull-request-has-tweet-with-poll-with-5-options/test.js
index 1dd253dd..37d4024e 100644
--- a/test/pull-request-has-tweet-with-poll-with-5-options/test.js
+++ b/test/pull-request-has-tweet-with-poll-with-5-options/test.js
@@ -69,17 +69,19 @@ nock("https://api.github.com")
     tap.equal(body.conclusion, "failure");
     tap.same(body.output, {
       title: "1 tweet(s)",
-      summary: `### ❌ Invalid
+      summary: `### ❌ Invalid Tweet
 
-> Here is my poll
->
-> ( ) option 1
-> ( ) option 2
-> ( ) option 3
-> ( ) option 4
-> ( ) option 5
+\`\`\`tweet
+Here is my poll
 
-Polls cannot have more than four options, found 5 options`,
+( ) option 1
+( ) option 2
+( ) option 3
+( ) option 4
+( ) option 5
+\`\`\`
+
+**Polls cannot have more than four options, found 5 options**`,
     });
 
     return true;
diff --git a/test/pull-request-has-tweet-with-poll/test.js b/test/pull-request-has-tweet-with-poll/test.js
index dcaf4c99..668acb15 100644
--- a/test/pull-request-has-tweet-with-poll/test.js
+++ b/test/pull-request-has-tweet-with-poll/test.js
@@ -68,16 +68,14 @@ nock("https://api.github.com")
     tap.equal(body.conclusion, "success");
     tap.same(body.output, {
       title: "1 tweet(s)",
-      summary: `### ✅ Valid
+      summary: `### ✅ Valid Tweet
 
-> Here is my poll
+- option 1
+- option 2
+- option 3
+- option 4
 
-The tweet includes a poll:
-
-> 🔘 option 1
-> 🔘 option 2
-> 🔘 option 3
-> 🔘 option 4`,
+> Here is my poll`,
     });
 
     return true;
diff --git a/test/pull-request-has-tweet-with-thread/event.json b/test/pull-request-has-tweet-with-thread/event.json
new file mode 100644
index 00000000..ad692d8e
--- /dev/null
+++ b/test/pull-request-has-tweet-with-thread/event.json
@@ -0,0 +1,22 @@
+{
+  "action": "opened",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000002",
+      "repo": {
+        "fork": false
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-has-tweet-with-thread/test.js b/test/pull-request-has-tweet-with-thread/test.js
new file mode 100644
index 00000000..955467f7
--- /dev/null
+++ b/test/pull-request-has-tweet-with-thread/test.js
@@ -0,0 +1,111 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = "";
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/tweets/thread.tweet b/tweets/thread.tweet
+new file mode 100644
+index 0000000..ec04564
+--- /dev/null
++++ b/tweets/thread.tweet
+@@ -0,0 +1,15 @@
++🧵 Here is a thread...
++
++---
++---
++poll:
++  - Banana
++  - Mango
++---
++
++Which fruit is more delicious?
++
++---
++We hope you enjoyed this thread...
++---
++We certainly did.`
+  );
+
+// create check run
+nock("https://api.github.com")
+  // get changed files
+  .post("/repos/twitter-together/action/check-runs", (body) => {
+    tap.equal(body.name, "preview");
+    tap.equal(body.head_sha, "0000000000000000000000000000000000000002");
+    tap.equal(body.status, "completed");
+    tap.equal(body.conclusion, "success");
+    tap.same(body.output, {
+      title: "1 tweet(s)",
+      summary: `### ✅ Valid Thread
+
+#### --- 🧵 1 ---
+
+> 🧵 Here is a thread...
+
+#### --- 🧵 2 ---
+
+- Banana
+- Mango
+
+> Which fruit is more delicious?
+
+#### --- 🧵 3 ---
+
+> We hope you enjoyed this thread...
+
+#### --- 🧵 4 ---
+
+> We certainly did.`,
+    });
+
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/pull-request-has-tweet/test.js b/test/pull-request-has-tweet/test.js
index 36d3c7a3..9be1e4c1 100644
--- a/test/pull-request-has-tweet/test.js
+++ b/test/pull-request-has-tweet/test.js
@@ -63,7 +63,7 @@ nock("https://api.github.com")
     tap.equal(body.conclusion, "success");
     tap.same(body.output, {
       title: "1 tweet(s)",
-      summary: "### ✅ Valid\n\n> Hello, world!",
+      summary: "### ✅ Valid Tweet\n\n> Hello, world!",
     });
 
     return true;
diff --git a/test/pull-request-invalid-tweet/test.js b/test/pull-request-invalid-tweet/test.js
index c984bd10..2341b056 100644
--- a/test/pull-request-invalid-tweet/test.js
+++ b/test/pull-request-invalid-tweet/test.js
@@ -66,11 +66,13 @@ nock("https://api.github.com", {
     tap.equal(body.conclusion, "failure");
     tap.same(body.output, {
       title: "1 tweet(s)",
-      summary: `### ❌ Invalid
+      summary: `### ❌ Invalid Tweet
 
-> Cupcake ipsum dolor sit amet chupa chups candy halvah I love. Apple pie gummi bears chupa chups jujubes I love cake jelly. Jelly candy canes pudding jujubes caramels sweet roll I love. Sweet fruitcake oat cake I love brownie sesame snaps apple pie lollipop. Pie dragée I love apple pie cotton candy candy chocolate bar.
+\`\`\`tweet
+Cupcake ipsum dolor sit amet chupa chups candy halvah I love. Apple pie gummi bears chupa chups jujubes I love cake jelly. Jelly candy canes pudding jujubes caramels sweet roll I love. Sweet fruitcake oat cake I love brownie sesame snaps apple pie lollipop. Pie dragée I love apple pie cotton candy candy chocolate bar.
+\`\`\`
 
-Tweet exceeds maximum length of 280 characters by 39 characters`,
+**Tweet exceeds maximum length of 280 characters by 39 characters**`,
     });
 
     return true;
diff --git a/test/pull-request-target-has-tweet-issue-comment/event.json b/test/pull-request-target-has-tweet-issue-comment/event.json
new file mode 100644
index 00000000..ad692d8e
--- /dev/null
+++ b/test/pull-request-target-has-tweet-issue-comment/event.json
@@ -0,0 +1,22 @@
+{
+  "action": "opened",
+  "pull_request": {
+    "number": 123,
+    "base": {
+      "ref": "main"
+    },
+    "head": {
+      "sha": "0000000000000000000000000000000000000002",
+      "repo": {
+        "fork": false
+      }
+    }
+  },
+  "repository": {
+    "default_branch": "main",
+    "name": "action",
+    "owner": {
+      "login": "twitter-together"
+    }
+  }
+}
diff --git a/test/pull-request-target-has-tweet-issue-comment/test.js b/test/pull-request-target-has-tweet-issue-comment/test.js
new file mode 100644
index 00000000..6678b992
--- /dev/null
+++ b/test/pull-request-target-has-tweet-issue-comment/test.js
@@ -0,0 +1,91 @@
+/**
+ * This test checks the happy path of pull request adding a new *.tweet file
+ */
+
+const nock = require("nock");
+const tap = require("tap");
+
+// SETUP
+process.env.GITHUB_EVENT_NAME = "pull_request_target";
+process.env.GITHUB_TOKEN = "secret123";
+process.env.GITHUB_EVENT_PATH = require.resolve("./event.json");
+
+// set other env variables so action-toolkit is happy
+process.env.GITHUB_REF = "";
+process.env.GITHUB_WORKSPACE = "";
+process.env.GITHUB_WORKFLOW = "";
+process.env.GITHUB_ACTION = "twitter-together";
+process.env.GITHUB_ACTOR = "";
+process.env.GITHUB_REPOSITORY = "";
+process.env.GITHUB_SHA = "";
+
+// MOCK
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // get changed files
+  .get("/repos/twitter-together/action/pulls/123/files")
+  .reply(200, [
+    {
+      status: "added",
+      filename: "tweets/hello-world.tweet",
+    },
+  ]);
+
+// get pull request diff
+nock("https://api.github.com", {
+  reqheaders: {
+    accept: "application/vnd.github.diff",
+    authorization: "token secret123",
+  },
+})
+  .get("/repos/twitter-together/action/pulls/123")
+  .reply(
+    200,
+    `diff --git a/tweets/hello-world.tweet b/tweets/hello-world.tweet
+new file mode 100644
+index 0000000..0123456
+--- /dev/null
++++ b/tweets/hello-world.tweet
+@@ -0,0 +1 @@
++Hello, world!`
+  );
+
+// check for comments
+nock("https://api.github.com", {
+  reqheaders: {
+    authorization: "token secret123",
+  },
+})
+  // no comments
+  .get("/repos/twitter-together/action/issues/123/comments")
+  .reply(200, []);
+
+// post comment
+nock("https://api.github.com")
+  // get changed files
+  .post("/repos/twitter-together/action/issues/123/comments", ({ body }) => {
+    tap.same(
+      body,
+      `## Found 1 new \`.tweet\` file(s)
+
+### ✅ Valid Tweet
+
+> Hello, world!
+
+---
+
+*Preview using 0000000000000000000000000000000000000002 generated by [Twitter, together!](https://github.com/twitter-together/action)*`
+    );
+    return true;
+  })
+  .reply(201);
+
+process.on("exit", (code) => {
+  tap.equal(code, 0);
+  tap.same(nock.pendingMocks(), []);
+});
+
+require("../../lib");
diff --git a/test/push-main-tweet-error/test.js b/test/push-main-tweet-error/test.js
index b18c14ef..2aff9068 100644
--- a/test/push-main-tweet-error/test.js
+++ b/test/push-main-tweet-error/test.js
@@ -45,7 +45,6 @@ nock("https://api.github.com", {
   .post(
     "/repos/twitter-together/action/commits/0000000000000000000000000000000000000002/comments",
     (body) => {
-      console.log(body.body);
       tap.equal(
         body.body,
         "Errors:\n\n- Tweet exceeds maximum length of 280 characters by 166 characters"