feat(agent): use repository PR templates and contributing rules before draft PR creation

[dangzitou]

背景

当前 OpenMeta 可以完成通用的 PR 创建流程：

• fork 仓库
• 创建分支
• 生成 PR draft
• 向上游仓库发起 draft PR

但从当前实现看，PR 标题、正文、branch naming、commit message 主要来自 OpenMeta 自己的固定逻辑和模型生成结果，而不是目标仓库的实际贡献规则。

这会带来一个问题：

PR 可能在技术上合理，但在仓库规则层面不合规。

例如：

• 没有遵循 CONTRIBUTING.md
• 没有套用 .github/PULL_REQUEST_TEMPLATE.md
• 没有满足 checklist 要求
• 分支命名不符合项目约定
• commit message 不符合仓库规范
• 缺少 issue linking / changelog / test note / breaking change note
• 没有遵守“先讨论后提 PR”之类的贡献流程

对于 OpenMeta 来说，这类 PR 很容易变成“低质量自动 PR”，即使改动本身不差，也会降低 merge potential。

问题

OpenMeta 当前更像是在“自己想一个 PR”，而不是“先理解这个仓库希望 PR 怎么写，再去生成 PR”。

这和 OpenMeta 的目标并不完全一致：

• OpenMeta 不只是要会改代码
• 还应该尽量减少垃圾 PR
• 应该尽量像一个认真读过贡献指南的贡献者

建议改进

在 Prepare workspace / Create draft PR 之间增加一个轻量的 repository contribution rules pass，至少包括：

1. 检测并读取以下文件（如果存在）：

   • CONTRIBUTING.md
   • .github/PULL_REQUEST_TEMPLATE.md
   • .github/pull_request_template.md
   • .github/PULL_REQUEST_TEMPLATE/*
   • CODEOWNERS
   • issue template / discussion policy / release note policy
   • commit convention related docs

2. 提取结构化规则，例如：

   • PR title format
   • commit message convention
   • branch naming convention
   • required checklist items
   • required validation/tests
   • required linked issue format
   • whether draft PRs are encouraged
   • whether maintainers require prior discussion

3. 将这些规则注入：

   • PR draft prompt
   • branch name generation
   • contribution commit message generation
   • final PR creation safety checks

4. 如果检测到强约束但当前 run 不满足：

   • 不要直接开 PR
   • 改为 needs_review / artifact-only
   • 在 trace 和 artifacts 中明确说明缺失项

预期收益

• 减少 technically-correct but process-invalid 的 PR
• 提高 PR 的 merge potential
• 更符合 OpenMeta “减少垃圾 PR” 的定位
• 让 agent 的行为更接近真实贡献者，而不是只会生成文本

建议验收

• 仓库存在 PR template 时，生成的 PR body 会显式遵循该模板
• 仓库存在 CONTRIBUTING 规则时，PR title / commit message / checklist 能体现这些要求
• 仓库要求特定 issue linking / test note / release note 时，PR draft 会自动补齐
• 如果规则无法满足，agent 不会盲目开 PR，而是收口为 review/artifacts
• trace / dossier 能展示本次识别到的 repository PR rules

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Background

OpenMeta can already perform the generic PR flow:

• fork the repository
• create a branch
• generate a PR draft
• open a draft PR against upstream

However, the current behavior appears to rely mostly on OpenMeta’s own fixed conventions and model-generated content, rather than the target repository’s actual contribution rules.

This creates a practical problem:

a PR may be technically reasonable, but still non-compliant with repository-specific contribution expectations.

Examples include:

• not following CONTRIBUTING.md
• ignoring .github/PULL_REQUEST_TEMPLATE.md
• missing required checklist items
• using a branch name that does not match project conventions
• using a commit message format that the repo does not accept
• omitting required issue links / test notes / changelog notes / breaking change notes
• skipping contribution workflow expectations such as “discuss before opening a PR”

For OpenMeta, this can easily produce “low-quality automated PRs” even when the underlying code change is decent.

Problem

OpenMeta currently behaves more like “generate a PR that seems reasonable” than “understand how this repository expects PRs to be written and submitted”.

That is misaligned with OpenMeta’s product goal:

• OpenMeta should not just write code
• it should also minimize low-signal PRs
• it should behave more like a contributor who actually read the repository’s contribution rules

Proposed improvement

Add a lightweight repository contribution rules pass between Prepare workspace and Create draft PR, including at least:

1. Detect and read these files when present:

   • CONTRIBUTING.md
   • .github/PULL_REQUEST_TEMPLATE.md
   • .github/pull_request_template.md
   • .github/PULL_REQUEST_TEMPLATE/*
   • CODEOWNERS
   • issue templates / discussion policy / release-note policy
   • commit convention related docs

2. Extract structured constraints such as:

   • PR title format
   • commit message convention
   • branch naming convention
   • required checklist items
   • required validation/tests
   • required issue-linking format
   • whether draft PRs are encouraged
   • whether prior maintainer discussion is expected

3. Feed these rules into:

   • the PR draft prompt
   • branch name generation
   • contribution commit message generation
   • final PR creation safety checks

4. If strong constraints are detected but the current run does not satisfy them:

   • do not open a PR blindly
   • fall back to needs_review / artifact-only mode
   • explain the missing requirements in trace and artifacts

Expected benefit

• reduce technically-correct but process-invalid PRs
• improve merge potential
• better align with OpenMeta’s “avoid garbage PRs” goal
• make the agent behave more like a real contributor rather than just a text generator

Suggested acceptance criteria

• if a repository has a PR template, the generated PR body explicitly follows it
• if a repository has contribution rules, PR title / commit message / checklist reflect them
• if a repo requires issue linking / test notes / release notes, the PR draft includes them
• if requirements cannot be satisfied, the agent falls back to review/artifacts instead of blindly opening a PR
• trace / dossier show the repository PR rules detected for the run