Outbound Plane→GitHub sync requires hardcoded "github" label , undocumented

打开 GitHub integration 的“how it works”页面，并找到“What gets synced?”部分。将其中关于双向同步的措辞与已报告的 github-label 要求进行比较，然后记录 outbound sync 要求不区分大小写的 github label，并说明如何应用它。完成标准是页面清楚地描述这一 opt-in 门槛以及其他标签的行为。

Summary:
After completing the GitHub App setup, configuring the workspace connection, connecting a personal account, and enabling Project Issue Sync with "bidirectional" turned on, Plane work items created in the UI still do not sync to GitHub.

Investigation of silo's compiled source at /app/apps/silo/dist/start.mjs (around line 31738 in the v2.3.0 bundle) reveals:

if (!labels || !labels.find((label) => label.name.toLowerCase() === E_INTEGRATION_KEYS.GITHUB.toLowerCase())) return res.status(202).send({ message: "Webhook received" });

Silo requires the Plane work item to have a label named literally github (case-insensitive). Work items without this label receive a 202 response and are silently dropped — no error, no log beyond the initial receipt.

The label name is hardcoded to the E_INTEGRATION_KEYS.GITHUB constant and is not configurable per-project, per-workspace, or via environment variable.

Impact:
This undocumented requirement was the final blocker after roughly 14 hours of debugging the same installation. I reached the Plane support draft stage before finding this in source. The "What gets synced?" documentation page describes Labels as a property that flows bidirectionally between systems ("If a Label doesn't exist in Plane, it will be created (and vice versa)") — which strongly implies any label flows, not that one specific label name acts as a sync gate.
The mismatch between UI promise and actual behavior is significant:

UI: "Project Issue Sync" configured with "bidirectional" enabled
Docs: "Issues created in GitHub are automatically created in the linked Plane project. With bidirectional sync enabled, work items created in Plane are also created in GitHub."
Reality: Plane→GitHub works only if the work item has a specific hardcoded label

Proposed documentation change:
On the GitHub integration "how it works" page, add a prominent note:

Outbound sync requires the github label

Work items created in Plane only sync to GitHub if they have a label named github (case-insensitive). This acts as an opt-in mechanism to prevent every Plane work item from being automatically published to GitHub. Work items without this label will remain Plane-only even when bidirectional sync is enabled.

Create the github label in your project's Labels settings, then apply it to any work item you want mirrored to GitHub. All other labels on the work item will propagate normally to GitHub during sync.

Feature request / secondary suggestion:
Consider making the gate label configurable per-project. Teams using existing label taxonomies (integration:github, gh, public, etc.) are forced to adopt github as a required magic string. A per-project setting "Sync issues labeled:" with a default of github would preserve the opt-in pattern while allowing taxonomy flexibility.

Alternatively, if the design intent is "sync all issues when bidirectional is enabled," then the label gate is a bug and should be removed.