implement CEP-6 public server announcements (full lifecycle)

[harsh04044]

This issue tracks closing the gap with the TS SDK's CEP-6 implementation, using the spec and TS SDK AnnouncementManager as the reference.

Supersedes #59 which had a higher-level plan.

1. Core data structures (foundation)

• Event kind constants: SERVER_ANNOUNCEMENT_KIND (11316), TOOLS_LIST_KIND (11317), RESOURCES_LIST_KIND (11318), RESOURCETEMPLATES_LIST_KIND (11319), PROMPTS_LIST_KIND
  (11320) in src/core/constants.rs
• Tag name constants: NAME, ABOUT, WEBSITE, PICTURE, SUPPORT_ENCRYPTION, SUPPORT_ENCRYPTION_EPHEMERAL in src/core/constants.rs
• DEFAULT_BOOTSTRAP_RELAY_URLS constant (6 relay URLs for CEP-17 discoverability) in src/core/constants.rs
• UNENCRYPTED_KINDS array containing all 5 announcement kinds in src/core/constants.rs
• ServerInfo struct with builder pattern (name, version, picture, website, about) in src/core/types.rs
• ServerAnnouncement struct for client-side parsing (pubkey, server_info, event_id, created_at) in src/discovery/mod.rs
• is_announced_server: bool config flag in NostrServerTransportConfig
• ProfileMetadata struct with name, about, picture, banner, website, nip05, lud16 + #[serde(flatten)] extra for custom fields (CEP-23) (feat: add ProfileMetadata type and update ServerAnnouncement parsing (CEP-6) #77)
• ServerAnnouncementContent struct - not needed. We serialize rmcp's raw InitializeResult directly as kind 11316 content, same as the TS SDK.

2. Server-side announcement publishing

• announce() → kind 11316 with ServerInfo content + common tags
• publish_tools(Vec<serde_json::Value>) → kind 11317
• publish_resources(Vec<serde_json::Value>) → kind 11318
• publish_prompts(Vec<serde_json::Value>) → kind 11320
• publish_resource_templates(Vec<serde_json::Value>) → kind 11319
• delete_announcements(reason) → NIP-09 kind 5 for all announcement kinds
• RMCP-typed publish variants: publish_tools_typed(), publish_resources_typed(), publish_prompts_typed(), publish_resource_templates_typed()
• extra_common_tags and pricing_tags setters on transport
• Add d tag to all replaceable events — not needed. Kinds 11316–11320 are standard replaceable (10000–19999 per NIP-01), replaced by pubkey+kind only. TS SDK doesn't add one either.
• Publish full InitializeResult as kind 11316 content (protocol_version, capabilities, server_info, instructions) instead of ServerInfo only (feat: auto-publish server announcements on start (CEP-6) #78 )

3. Client-side discovery

• discover_servers() → fetches kind 11316, returns Vec<ServerAnnouncement>
• discover_tools() → fetches kind 11317
• discover_resources() → fetches kind 11318
• discover_prompts() → fetches kind 11320
• discover_resource_templates() → fetches kind 11319
• RMCP-typed discovery variants: discover_tools_typed(), discover_resources_typed(), discover_prompts_typed(), discover_resource_templates_typed()
• Update ServerAnnouncement parsing to handle ServerAnnouncementContent (extract protocol_version, capabilities alongside server_info) (feat: add ProfileMetadata type and update ServerAnnouncement parsing (CEP-6) #77 )

4. Discovery tag emission & learning (done via CEP-35)

• get_common_tags() helper: builds server info + capability tags from config (feat: add tag composition, server discovery tag emission and capability learning for CEP-35 #57)
• take_pending_server_discovery_tags(session): returns common tags on first response per client, empty after (feat: add tag composition, server discovery tag emission and capability learning for CEP-35 #57)
• Wire into send_response() and send_notification(): include discovery tags on first message to each client (feat: add tag composition, server discovery tag emission and capability learning for CEP-35 #57)
• support_encryption and support_encryption_ephemeral capability tags auto-added (feat: add tag composition, server discovery tag emission and capability learning for CEP-35 #57)
• Server-side capability learning: learn_peer_capabilities() on inbound event tags, OR-assign to ClientSession (feat: add tag composition, server discovery tag emission and capability learning for CEP-35 #57)

5. AnnouncementManager orchestrator

• Extract announcement logic into dedicated AnnouncementManager struct (refactor: extract AnnouncementManager from NostrServerTransport (CEP-35) #74)
• get_server_info_tags(), get_capability_tags(), get_common_tags() with caching and cache invalidation (refactor: extract AnnouncementManager from NostrServerTransport (CEP-35) #74)
• set_extra_common_tags(), set_internal_common_tags(), set_pricing_tags() on manager (refactor: extract AnnouncementManager from NostrServerTransport (CEP-35) #74)
• Refactor announce(), publish_tools(), etc. to delegate to AnnouncementManager (refactor: extract AnnouncementManager from NostrServerTransport (CEP-35) #74)
• Schema-to-kind mapping: define AnnouncementMapping that maps MCP response schemas to Nostr event kinds (InitializeResult → 11316, ListToolsResult → 11317,
  ListResourcesResult → 11318, ListResourceTemplatesResult → 11319, ListPromptsResult → 11320) (feat: auto-publish server announcements on start (CEP-6) #78 )
• publish_public_announcements(): send synthetic MCP requests (initialize, tools/list, resources/list, resourceTemplates/list, prompts/list) with sentinel id
  'announcement' and publish results as Nostr events (feat: auto-publish server announcements on start (CEP-6) #78 )
• handle_announcement_response(message): intercept responses with sentinel id, validate against schema, map to event kind, call publish_announcement_event() (feat: auto-publish server announcements on start (CEP-6) #78 )
• Auto-publish on server start when is_announced_server: true — spawn announcement task in start() (feat: auto-publish server announcements on start (CEP-6) #78 )
• Initialization timeout (10s default) for synthetic MCP handshake with graceful failure (feat: auto-publish server announcements on start (CEP-6) #78 )

6. Relay list & profile metadata publishing

• publish_relay_list() → kind 10002 (NIP-65): empty content, tags = [["r", relay_url], ...] for each configured relay (feat: relay list and profile metadata publishing (CEP-6) #79 )
• get_discoverability_publish_relay_urls(): merge configured + bootstrap relay URLs, deduplicate (feat: relay list and profile metadata publishing (CEP-6) #79 )
• Smart local relay detection: skip default bootstrap relays when all configured relays are local (ws://127.0.0.1:*) (feat: relay list and profile metadata publishing (CEP-6) #79 )
• Configurable bootstrap_relay_urls with opt-out (publish_relay_list: false) (feat: relay list and profile metadata publishing (CEP-6) #79 )
• publish_profile_metadata() → kind 0 (NIP-01 / CEP-23): content = JSON-serialized ProfileMetadata, empty tags (opt-in via config) (feat: relay list and profile metadata publishing (CEP-6) #79 )

7. Tests

• d tag presence verification - not needed (see section 2)
• Full InitializeResult content serialization/deserialization roundtrip (feat: add ProfileMetadata type and update ServerAnnouncement parsing (CEP-6) #77 )
• Schema-to-kind mapping: each MCP result type maps to correct Nostr event kind (feat: auto-publish server announcements on start (CEP-6) #78 )
• Auto-publish lifecycle: announce: true triggers synthetic requests and event publishing on start (feat: auto-publish server announcements on start (CEP-6) #78 )
• Initialization timeout: graceful failure when MCP handler doesn't respond (feat: schema mapping, delete fix, and gap closures CEP-6 #81 )
• Relay list publishing: correct kind, tags, content (feat: relay list and profile metadata publishing (CEP-6) #79 )
• Bootstrap relay behavior: skipped for local-only configurations (feat: relay list and profile metadata publishing (CEP-6) #79 )
• Profile metadata publishing: correct kind, content serialization (feat: add ProfileMetadata type and update ServerAnnouncement parsing (CEP-6) #77 )
• Delete announcement: publishes kind 5 for all announcement kinds (feat: schema mapping, delete fix, and gap closures CEP-6 #81 )
• Roundtrip integration: publish → discover for all capability types (feat: schema mapping, delete fix, and gap closures CEP-6 #81 )

Reference

• CEP-6 spec: contextvm-docs/src/content/docs/spec/ceps/cep-6.md
• TS SDK AnnouncementManager: sdk/src/transport/nostr-server/announcement-manager.ts (721 LOC, 17 tests)
• TS SDK SessionStore: sdk/src/transport/nostr-server/session-store.ts (hasSentCommonTags tracking)
• TS SDK constants: sdk/src/core/constants.ts (event kinds 11316–11320)
• rs-sdk existing implementation: src/transport/server/mod.rs:669-897 (publish methods + tag helpers)
• rs-sdk discovery: src/discovery/mod.rs (client-side discovery API)
• rs-sdk constants: src/core/constants.rs (kinds + tags)
• rs-sdk types: src/core/types.rs (ServerInfo, ClientSession)