feat: serve amiusing.requestly.io response inline from the proxy

[dinex-dev]

Summary

• Replaces AmisuingMiddleware's header-injection with a direct response substitution: requests to amiusing.requestly.io are answered locally with a self-contained Success HTML page, without ever forwarding upstream.
• Mirrors ssl_cert_middleware's pattern — runs as a pre-rules middleware via init_amiusing_handler, short-circuiting before the rule engine is consulted. No dependency on the rule system, the rule schema, or the requestly-core BLACK_LIST_DOMAINS check.
• HTML body (carrying the existing two-column "Yes" design + a {"amiusing": true} JSON marker) is extracted to amiusing_yes_page.js for readability; no build changes — tsc handles the new module naturally.
• Version bump to 1.3.15.

Why

Today the "Yes" indicator on amiusing.requestly.io depends on the proxy injecting a header that the origin's Next.js app reads. Once the origin migrates off Heroku to a static page (RQ-2153), the header path stops working. Serving the response inline from the proxy is durable across that migration and any future origin changes.

Test plan

• Built locally (npm run build).
• Smoke-tested via a linked install in requestly-desktop-app: through the desktop proxy, curl -x http://localhost:8281 http://amiusing.requestly.io returns the Success HTML; the request never reaches origin.
• Confirmed the rule engine doesn't fire on these requests (no "Rules Applied" indicator in the desktop network log).
• Verify CI passes.
• Publish to npm (1.3.15) before the companion desktop-app dep bump can merge.

Follow-up

• Desktop-app dep bump: companion PR in requestly/requestly-desktop-app.

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features
  • Added a confirmation page that displays when Requestly is detected. The page includes success messaging, troubleshooting documentation links, and resources to explore Requestly's features.

[coderabbitai]

Walkthrough

The PR adds an "Am I Using Requestly" feature to the proxy middleware. A new file exports AMIUSING_YES_HTML, a static HTML template containing responsive layout styling, status messaging, troubleshooting documentation links, and an embedded JSON marker. The middleware now intercepts requests to amiusing.requestly.io, writes a 200 response with the HTML body and no-store caching directive, includes an amiusingrequestly: "true" response header, and short-circuits without upstreaming the request.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately and concisely describes the main change: serving amiusing.requestly.io responses directly from the proxy instead of relying on header injection or upstream forwarding.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/amiusing-builtin-interception

Warning

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[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@requestly/requestly-proxy@99

commit: 2adac48

[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/components/proxy-middleware/middlewares/amiusing_middleware.js`:
- Around line 24-25: The host check is too strict and will miss matches when the
incoming host includes a port or different casing; update the condition that
uses ctx.proxyToServerRequestOptions.host and AMIUSING_HOST to compare
normalized hostnames by extracting the hostname (strip any port portion after
':' and remove surrounding IPv6 brackets if present), lowercasing and trimming
both sides, then compare equality (e.g., normalize incomingHost =
stripPortAndBrackets(ctx.proxyToServerRequestOptions.host).toLowerCase() and
compare to AMIUSING_HOST.toLowerCase()); return early only if they do not match.

In `@src/components/proxy-middleware/middlewares/amiusing_yes_page.js`:
- Line 86: Update the user-facing heading text in the AMI using "yes" page:
replace the current h2 content "What's next you ask ?" with properly punctuated
copy "What's next, you ask?" in the component that renders the <h2>
(amiusing_yes_page.js) so the displayed heading uses the comma and moves the
question mark directly after the phrase.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 36c346f1-4473-4a69-b2dc-815fee3420ac

📥 Commits

Reviewing files that changed from the base of the PR and between fcf19c0 and 7ad2da6.

⛔ Files ignored due to path filters (3)

• dist/components/proxy-middleware/middlewares/amiusing_middleware.js is excluded by !**/dist/**
• dist/components/proxy-middleware/middlewares/amiusing_yes_page.d.ts is excluded by !**/dist/**
• dist/components/proxy-middleware/middlewares/amiusing_yes_page.js is excluded by !**/dist/**

📒 Files selected for processing (3)

• package.json
• src/components/proxy-middleware/middlewares/amiusing_middleware.js
• src/components/proxy-middleware/middlewares/amiusing_yes_page.js

[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (1)

src/components/proxy-middleware/middlewares/amiusing_middleware.js (1)

28-36: ⚡ Quick win

Consider adding error handling around response operations.

While the static HTML content is unlikely to cause issues, adding a try-catch around the response write operations would improve resilience in case of unexpected errors (network issues, client disconnection, etc.).

🛡️ Optional defensive wrapper

+    try {
       ctx.proxyToClientResponse.writeHead(200, {
         "Content-Type": "text/html",
         "Cache-Control": "no-store",
         // Echo the legacy request-side marker as a response header too so any
         // downstream consumer that historically inspected `amiusingrequestly`
         // continues to see it after we stopped forwarding upstream.
         "amiusingrequestly": "true",
       });
       ctx.proxyToClientResponse.end(AMIUSING_YES_HTML);
+    } catch (err) {
+      console.error("[AmisuingMiddleware] Failed to send response:", err);
+      // Response already started or client disconnected; nothing more to do
+    }

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/components/proxy-middleware/middlewares/amiusing_middleware.js` around
lines 28 - 36, Wrap the response write operations that use
ctx.proxyToClientResponse.writeHead and
ctx.proxyToClientResponse.end(AMIUSING_YES_HTML) in a try-catch to handle
unexpected errors (e.g., client disconnects or network issues); on error, check
ctx.proxyToClientResponse.headersSent or presence and attempt a safe cleanup
(log the error via your logger and call ctx.proxyToClientResponse.end() if
possible) to ensure the connection is closed gracefully and no uncaught
exceptions bubble up.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/components/proxy-middleware/middlewares/amiusing_middleware.js`:
- Line 10: The file uses ES6 import syntax for AMIUSING_YES_HTML which conflicts
with the repo's CommonJS setup; fix by replacing the ES module import with a
CommonJS require (use const { AMIUSING_YES_HTML } =
require("./amiusing_yes_page")) in
src/components/proxy-middleware/middlewares/amiusing_middleware.js so the source
matches the project's "module": "commonjs" and "type": "commonjs" configuration,
or alternatively update tsconfig.json ("module": "esnext") and package.json
("type": "module") if you intend to switch the whole project to ESM.

---

Nitpick comments:
In `@src/components/proxy-middleware/middlewares/amiusing_middleware.js`:
- Around line 28-36: Wrap the response write operations that use
ctx.proxyToClientResponse.writeHead and
ctx.proxyToClientResponse.end(AMIUSING_YES_HTML) in a try-catch to handle
unexpected errors (e.g., client disconnects or network issues); on error, check
ctx.proxyToClientResponse.headersSent or presence and attempt a safe cleanup
(log the error via your logger and call ctx.proxyToClientResponse.end() if
possible) to ensure the connection is closed gracefully and no uncaught
exceptions bubble up.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 0a647aab-a7f3-443d-9498-7ae652f8411b

📥 Commits

Reviewing files that changed from the base of the PR and between 7ad2da6 and 2adac48.

⛔ Files ignored due to path filters (1)

• dist/components/proxy-middleware/middlewares/amiusing_middleware.js is excluded by !**/dist/**

📒 Files selected for processing (1)

• src/components/proxy-middleware/middlewares/amiusing_middleware.js