fix(kyberforge): correct field classification and fill provenance gaps in plugin-author and marketplace-author

## Why

The manifest-fields tables in both skills used imprecise labels ("CC-only",
"Copilot-only") that conflated two distinct reasons a field appears in only
one manifest: platform constraint (the other tool does not support the field
at all) versus repo convention (both tools support it, but the scaffold places
it in one manifest by design). This caused agents to treat convention
boundaries as hard platform constraints, producing unnecessary errors when
updating manifests for dual-tool repos.

Provenance was also incomplete: sources.md files were missing entries for
sources that had been consulted and were already contributing to SKILL.md
and manifest-fields.md content, making the evidence chain unverifiable.

## Implementation Notes

Field classification now uses three explicit categories — shared, platform
(one tool does not support the field), and convention (both tools support it;
scaffold places it in one manifest by design). The distinction matters because
convention fields may legitimately appear in the other manifest when there is
a deliberate reason; platform fields may not.

New gotchas added to plugin-author: agent files silently ignore hooks,
mcpServers, and permissionMode frontmatter; claude plugin tag --push requires
a clean working tree; --dry-run preview before tagging; --strict flag on
validate. New gotchas in marketplace-author: metadata object as Copilot CLI
canonical location for top-level fields; strict: false for dual-tool plugins;
sha takes precedence over ref for pinning; --strict flag on validate.

tests/ removed from plugin-author because new-plugin.sh has no branching
logic warranting a bats suite at this stage.

## Impact

Skill prompt changes only — no runtime code affected. Agents using these
skills will now correctly distinguish convention from constraint when deciding
which manifest to update for a given field.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plugins/kyberforge/skills/plugin-author/references/sources.md

@@ -2,9 +2,21 @@
 source_keys:
   - context7-websites-code-claude
   - claude-code-plugins-docs
+  - claude-code-subagents-docs
+  - context7-github-en-copilot
   - github-cli-plugin-reference
   - github-plugins-creating
   - github-plugins-finding-installing
+  - github-custom-agents-configuration
+  - github-plugins-marketplace
+  - github-sdk-custom-agents
+  - github-changelog-copilot-extensions-ga
+  - github-changelog-copilot-extensions-sunset
+  - github-docs-copilot-extensions-skillsets
+  - github-docs-copilot-extensions-building
+  - vscode-chat-participant-api
+  - github-marketplace-copilot-extensions
+  - github-docs-marketplace-listing-requirements
 ---
 
 # Sources
@@ -30,7 +42,7 @@ source_keys:
 - **URL:** https://docs.github.com/en/copilot/reference/copilot-cli-reference/cli-plugin-reference
 - **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
 - **Description:** Full Copilot CLI plugin reference — `plugin.json` schema (all fields, types, constraints), marketplace.json schema, CLI commands, manifest lookup order
-- **Contributing files:** SKILL.md, scripts/new-plugin.sh, references/manifest-fields.md
+- **Contributing files:** SKILL.md, references/manifest-fields.md
 - **Status:** `extracted`
 
 ## github-plugins-creating
@@ -38,7 +50,7 @@ source_keys:
 - **URL:** https://docs.github.com/en/copilot/how-tos/copilot-cli/customize-copilot/plugins-creating
 - **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
 - **Description:** How-to for creating Copilot CLI plugins — plugin structure, Copilot manifest fields, development lifecycle, hooks format, MCP config
-- **Contributing files:** SKILL.md, scripts/new-plugin.sh
+- **Contributing files:** SKILL.md
 - **Status:** `extracted`
 
 ## github-plugins-finding-installing
@@ -48,3 +60,99 @@ source_keys:
 - **Description:** Finding and installing Copilot CLI plugins — install spec formats, marketplace registration, `copilot plugin` CLI commands
 - **Contributing files:** SKILL.md
 - **Status:** `extracted`
+
+## claude-code-subagents-docs
+
+- **URL:** https://code.claude.com/docs/en/sub-agents
+- **Research doc:** plugins/kyberforge/docs/research/docs/claude-code-plugins/sources.md
+- **Description:** Official Claude Code subagent reference — definition format, all frontmatter fields, scope priority, built-in agents, CLI flags, environment variables, known limitations
+- **Contributing files:** SKILL.md
+- **Status:** `extracted`
+
+## context7-github-en-copilot
+
+- **URL:** context7:/websites/github_en_copilot
+- **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
+- **Description:** Official GitHub Copilot documentation indexed by Context7; covers CLI plugins, custom agents, SDK, and marketplace
+- **Contributing files:** SKILL.md, references/manifest-fields.md
+- **Status:** `extracted`
+
+## github-custom-agents-configuration
+
+- **URL:** https://docs.github.com/en/copilot/reference/custom-agents-configuration
+- **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
+- **Description:** Reference for cloud and IDE custom agent definition format — frontmatter fields, tool aliases, MCP server config, secrets interpolation, scoping hierarchy
+- **Contributing files:** (none)
+- **Status:** `extracted`
+
+## github-plugins-marketplace
+
+- **URL:** https://docs.github.com/en/copilot/how-tos/copilot-cli/customize-copilot/plugins-marketplace
+- **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
+- **Description:** How-to for creating and publishing a plugin marketplace — marketplace.json structure, hosting options, registration commands
+- **Contributing files:** (none)
+- **Status:** `extracted`
+
+## github-sdk-custom-agents
+
+- **URL:** https://docs.github.com/en/copilot/how-tos/copilot-sdk/features/custom-agents
+- **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
+- **Description:** SDK custom agent API — CustomAgentConfig fields in all five languages, session config, sub-agent lifecycle events, tool scoping, permission handling
+- **Contributing files:** (none)
+- **Status:** `extracted`
+
+## github-changelog-copilot-extensions-ga
+
+- **URL:** https://github.blog/changelog/2025-02-19-announcing-the-general-availability-of-github-copilot-extensions/
+- **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
+- **Description:** Announcement of GitHub Copilot Extensions general availability (February 2025) — OIDC auth, all license tiers, VS Code/Visual Studio/JetBrains/GitHub.com support
+- **Contributing files:** (none)
+- **Status:** `referenced`
+
+## github-changelog-copilot-extensions-sunset
+
+- **URL:** https://github.blog/changelog/2025-09-24-deprecate-github-copilot-extensions-github-apps/
+- **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
+- **Description:** Sunset notice for GitHub App-based Copilot Extensions — creation blocked Sep 24, 2025; full shutdown Nov 10, 2025; MCP servers recommended as replacement
+- **Contributing files:** (none)
+- **Status:** `referenced`
+
+## github-docs-copilot-extensions-skillsets
+
+- **URL:** https://docs.github.com/en/copilot/concepts/build-copilot-extensions/skillsets-for-copilot-extensions
+- **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
+- **Description:** Concept doc for Copilot Extension skillsets — up to 5 skills per extension, Copilot handles routing/prompt crafting/response, contrast with agent extensions
+- **Contributing files:** (none)
+- **Status:** `referenced`
+
+## github-docs-copilot-extensions-building
+
+- **URL:** https://docs.github.com/en/copilot/building-copilot-extensions/setting-up-copilot-extensions
+- **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
+- **Description:** How-to for setting up a Copilot Extension — GitHub App registration, Copilot Chat permission, Copilot Editor Context permission, backend URL configuration
+- **Contributing files:** (none)
+- **Status:** `referenced`
+
+## vscode-chat-participant-api
+
+- **URL:** https://code.visualstudio.com/api/extension-guides/ai/chat
+- **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
+- **Description:** VS Code Chat Participant API — createChatParticipant(), package.json contributes.chatParticipants, Language Model API, @mention invocation in Copilot Chat
+- **Contributing files:** (none)
+- **Status:** `referenced`
+
+## github-marketplace-copilot-extensions
+
+- **URL:** https://github.com/marketplace?type=apps&copilot_app=true
+- **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
+- **Description:** GitHub Marketplace listing for Copilot Extensions — browsable list of available extensions (historical; page remains live but product is sunset)
+- **Contributing files:** (none)
+- **Status:** `referenced`
+
+## github-docs-marketplace-listing-requirements
+
+- **URL:** https://docs.github.com/en/apps/github-marketplace/creating-apps-for-github-marketplace/requirements-for-listing-an-app
+- **Research doc:** plugins/kyberforge/docs/research/docs/github-copilot-plugins/sources.md
+- **Description:** Requirements for listing a GitHub App on the GitHub Marketplace — verified publisher, capability description, UX stability, submission and review process
+- **Contributing files:** (none)
+- **Status:** `referenced`