Gateway Runtime Readme.md file addition

[slahirucd7]

Purpose

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Relates with: #1856

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Documentation

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

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Run ID: 651bcb91-608c-4b02-915c-bab7aa45fa74

📥 Commits

Reviewing files that changed from the base of the PR and between e2d495c and 69d00ff.

📒 Files selected for processing (1)

• gateway/gateway-runtime/README.md

✅ Files skipped from review due to trivial changes (1)

• gateway/gateway-runtime/README.md

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📝 Walkthrough

Summary

This pull request adds comprehensive documentation for the Gateway Runtime component in a new file: gateway/gateway-runtime/README.md.

Changes

Added: gateway/gateway-runtime/README.md (+188 lines)

The README documents the Gateway Runtime architecture and operations, including:

• Architecture overview describing the two cooperating processes—Router (Envoy Proxy) and Policy Engine (Envoy ext_proc)—and dynamic configuration via xDS from the Gateway Controller
• Request flow diagrams and explanations for Go policies (compiled in-process into the Policy Engine) and Python policies (executed by a separate Python Executor via a local gRPC socket)
• Component responsibilities: Router, Policy Engine, Python Executor, and Gateway Builder (build-time compiler for policies)
• Build and development instructions (prerequisites, make targets for build, debug image with dlv on port 2346, test targets, and protobuf regeneration)
• Deployment and runtime configuration: environment variables with defaults, per-process CLI argument examples, and exposed ports (HTTP/HTTPS, Envoy admin, Policy Engine metrics)
• Project directory layout, links to the Gateway Debug Guide and Policy Engine README for custom policies
• Logging behavior and guidance for verbose structured logs (via LOG_LEVEL=debug)

No changes to exported/public code entities were made.

Walkthrough

Added a new README at gateway/gateway-runtime/ describing the Gateway Runtime architecture and deployment. It defines a two-process model: Router (Envoy proxy) and Policy Engine (Envoy ext_proc), with optional Python Executor for Python policies. The document includes request-flow diagrams for Go (in-process) and Python (delegated via local gRPC) policies, component responsibilities, the Gateway Builder compile step, make targets for build/test/protobuf regeneration (including a dlv debug image), runtime environment variables and per-process CLI examples, exposed ports, project layout, links to debugging and policy-writing guides, and structured logging behavior (verbose with LOG_LEVEL=debug).

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description follows the template structure but most sections contain only placeholders or empty prompts without substantive content filled in by the author.	Complete the description by filling in Goals, Approach, User stories, Documentation, Automation tests, Security checks, Samples, Related PRs, and Test environment sections with relevant details about the README addition.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: addition of a Gateway Runtime README file. It is clear, specific, and directly related to the changeset.
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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[coderabbitai]

Actionable comments posted: 3

🤖 Prompt for all review comments with AI agents

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

Inline comments:
In `@gateway/gateway-runtime/README.md`:
- Around line 26-36: The fenced ASCII diagram in the README (the block starting
with "API Consumer" and containing lines like "Router (Envoy Proxy)" and "Policy
Engine") lacks a language specifier; update the opening fence from ``` to
```text so the block becomes a ```text fenced code block to satisfy the markdown
linter and keep the diagram formatting intact.
- Around line 11-20: The fenced code block containing the ASCII diagram (the
triple-backticks that precede the diagram lines like "API Consumer" and "Router
(Envoy Proxy)") lacks a language specifier; update that opening fence to include
a language (e.g., use ```text) so the markdown linter warning is resolved and
the diagram is treated as plain text in README.md.
- Around line 193-209: The fenced code block containing the directory tree
starting with "gateway-runtime/" is missing a language specifier; update the
opening fence from ``` to ```text so the markdown linter stops warning (i.e.,
change the directory-tree block's fence to use "text" as the language
specifier).

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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: 2e971591-038d-4abd-96e5-0bc0afa9a85c

📥 Commits

Reviewing files that changed from the base of the PR and between 2e4af87 and e2d495c.

📒 Files selected for processing (1)

• gateway/gateway-runtime/README.md