docs: add generative ai contribution guidelines (#19427)

Initial language that gives us something to point to if needed.

docs/about/contributing/AI_CONTRIBUTING.md

@@ -0,0 +1,32 @@
+# AI Contribution Guidelines
+
+This document defines rules for contributions where an AI system is the primary author of the code (i.e., most of the pull request was generated by AI).
+It applies to all Coder repositories and is a supplement to the [existing contributing guidelines](./CONTRIBUTING.md), not a replacement.
+
+For minor AI-assisted edits, suggestions, or completions where the human contributor is clearly the primary author, these rules do not apply — standard contributing guidelines are sufficient.
+
+## Disclosure
+
+Contributors must **disclose AI involvement** in the pull request description whenever these guidelines apply.
+
+## Human Ownership & Attribution
+
+- All pull requests must be opened under **user accounts linked to a human**, and not an application ("bot account").
+- Contributors are personally accountable for the content of their PRs, regardless of how it was generated.
+
+## Verification & Evidence
+
+All AI-assisted contributions require **manual verification**.
+Contributions without verification evidence will be rejected.
+
+- Test your changes yourself. Don’t assume AI is correct.
+- Provide screenshots showing that the change works as intended.
+  - For visual/UI changes: include before/after screenshots.
+  - For CLI or backend changes: include terminal or api output.
+
+## Why These Rules Exist
+
+Traditionally, maintainers assumed that producing a pull request required more effort than reviewing it.
+With AI-assisted tools, the balance has shifted: generating code is often faster than reviewing it.
+
+Our guidelines exist to safeguard maintainers’ time, uphold contributor accountability, and preserve the overall quality of the project.

docs/about/contributing/CONTRIBUTING.md

@@ -236,6 +236,11 @@ Breaking changes can be triggered in two ways:
   [`release/breaking`](https://github.com/coder/coder/issues?q=sort%3Aupdated-desc+label%3Arelease%2Fbreaking)
   label to a PR that has, or will be, merged into `main`.
 
+### Generative AI
+
+Using AI to help with contributions is acceptable, but only if the [AI Contribution Guidelines](./AI_CONTRIBUTING.md)
+are followed. If most of your PR was generated by AI, please read and comply with these rules before submitting.
+
 ### Security
 
 > [!CAUTION]

docs/images/icons/ai_intelligence.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" height="24px" viewBox="0 -960 960 960" width="24px" fill="#000000"><path d="M323-160q-11 0-20.5-5.5T288-181l-78-139h58l40 80h92v-40h-68l-40-80H188l-57-100q-2-5-3.5-10t-1.5-10q0-4 5-20l57-100h104l40-80h68v-40h-92l-40 80h-58l78-139q5-10 14.5-15.5T323-800h97q17 0 28.5 11.5T460-760v160h-60l-40 40h100v120h-88l-40-80h-92l-40 40h108l40 80h112v200q0 17-11.5 28.5T420-160h-97Zm217 0q-17 0-28.5-11.5T500-200v-200h112l40-80h108l-40-40h-92l-40 80h-88v-120h100l-40-40h-60v-160q0-17 11.5-28.5T540-800h97q11 0 20.5 5.5T672-779l78 139h-58l-40-80h-92v40h68l40 80h104l57 100q2 5 3.5 10t1.5 10q0 4-5 20l-57 100H668l-40 80h-68v40h92l40-80h58l-78 139q-5 10-14.5 15.5T637-160h-97Z"/></svg>

docs/manifest.json

@@ -76,6 +76,12 @@
 							"description": "Security vulnerability disclosure policy",
 							"path": "./about/contributing/SECURITY.md",
 							"icon_path": "./images/icons/lock.svg"
+						},
+						{
+							"title": "AI Contribution Guidelines",
+							"description": "Guidelines for AI-generated contributions.",
+							"path": "./about/contributing/AI_CONTRIBUTING.md",
+							"icon_path": "./images/icons/ai_intelligence.svg"
 						}
 					]
 				}