feat: add interceptor

[SiebeBaree]

Summary by CodeRabbit

Release Notes

• New Features

  • Added HTTP request interception with configurable matching rules
  • Support for URL rewriting, header manipulation, and body overrides per rule
  • Per-rule workspace, project, and environment configuration overrides

• Chores

  • Node.js minimum version requirement updated to >=18
  • Added new runtime dependency

• Tests

  • Comprehensive test coverage added for interceptor functionality

[SiebeBaree]

• feat: add interceptor #4 👈 (View in Graphite)
• main

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[coderabbitai]

Walkthrough

This pull request introduces HTTP request interception capabilities to the Enkryptify SDK. It adds a new @mswjs/interceptors runtime dependency (v0.41.4) and Node.js >=18 engine requirement, implements an HttpInterceptor class that intercepts outbound fetch/Node HTTP requests and routes them through the Enkryptify proxy based on configured rules. The PR refactors proxy internals to expose sendProxyWire and ProxySendContext for reuse, introduces interceptor configuration types with rule matching via string prefix/RegExp/function, optional URL/header/body rewrites, and per-rule proxy overrides. It adds utility functions for URL templating, header merging with hop-by-hop filtering, and body resolution supporting JSON/function transformations. The Enkryptify class integrates optional interceptor lifecycle management, exposing an _interceptorReady() method for test coordination. Comprehensive test coverage validates matching logic, body handling, error paths, and interceptor lifecycle behavior.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~90 minutes

Possibly related PRs

• feat: added support for proxy #3: Modifies proxy-related code (src/proxy.ts) and exported types to refactor sendProxyWire and ProxySendContext, which serve as the foundation for the HTTP interceptor integration in this PR.
• SDK v0.1 #1: Extends core SDK files (src/enkryptify.ts, src/errors.ts, src/index.ts, src/types.ts) that this PR builds upon and directly integrates with for interceptor feature implementation.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 66.67% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat: add interceptor' directly and clearly summarizes the main change—adding HTTP interceptor functionality to the SDK.
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 04-21-feat_add_interceptor

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/enkryptify.ts`:
- Around line 134-135: The code reads interceptorConfig.rules.length without
validating rules' shape; update the guard so you only access .length when rules
is an array (e.g., use Array.isArray(interceptorConfig.rules) or coerce to an
array) and handle bad shapes by either treating rules as empty or throwing a
controlled SDK error; change the condition around interceptorConfig (the block
that checks interceptorConfig.enabled and currently reads
interceptorConfig.rules.length) to validate interceptorConfig.rules before using
.length and keep the rest of the block (including usage of this.#proxy._ctx)
unchanged.

In `@src/internal/template.ts`:
- Around line 59-67: mergeHeaders currently strips hop-by-hop headers from input
but then applies overrides which can reintroduce them; update the overrides loop
in mergeHeaders to ignore any override whose lower-cased key is in the
hop-by-hop set (e.g. HOP_BY_HOP_HEADERS) so that overrides cannot add those
headers back, and still allow deletes (value === undefined) to remove headers
but never re-add a hop-by-hop header to out.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

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

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 9c8c514c-1f63-494f-9fb8-19004e7d62da

📥 Commits

Reviewing files that changed from the base of the PR and between e05bb47 and 4bb17b5.

⛔ Files ignored due to path filters (1)

• pnpm-lock.yaml is excluded by !**/pnpm-lock.yaml

📒 Files selected for processing (9)

• package.json
• src/enkryptify.ts
• src/errors.ts
• src/index.ts
• src/interceptor.ts
• src/internal/template.ts
• src/proxy.ts
• src/types.ts
• tests/interceptor.test.ts