fix(churn): speak warpline-mcp's newline JSON-RPC + honest paging/keying disclosure

crates/loomweave-cli/src/serve.rs

@@ -11,6 +11,7 @@ use loomweave_federation::config::{
     select_provider_with_env,
 };
 use loomweave_federation::filigree::FiligreeHttpClient;
+use loomweave_federation::warpline::WarplineMcpClient;
 use loomweave_llm::{
     ApiEmbeddingProvider, ApiEmbeddingProviderConfig, ClaudeCliProvider, ClaudeCliProviderConfig,
     CodexCliProvider, CodexCliProviderConfig, EmbeddingProvider, EmbeddingProviderError,
@@ -91,6 +92,12 @@ pub fn run(path: &Path, config_path: Option<&Path>) -> Result<()> {
     )
     .context("build Filigree HTTP client")?;
 
+    // Read-only Warpline churn consumer for the high-churn / recently-changed
+    // surfaces. `None` when disabled (the default) — the surfaces degrade
+    // honestly. Enrich-only, dependency-sink: nothing flows loomweave→warpline.
+    let warpline_client =
+        WarplineMcpClient::from_config(&config.integrations.warpline, Some(&project_root));
+
     let diagnostics = loomweave_mcp::DiagnosticsContext {
         llm: llm_diagnostics,
         filigree: filigree_resolution,
@@ -127,6 +134,7 @@ pub fn run(path: &Path, config_path: Option<&Path>) -> Result<()> {
         llm_provider,
         semantic_search_state(&config.semantic_search, embedding_provider),
         filigree_client,
+        warpline_client,
         diagnostics,
         loomweave_mcp::McpToolPolicy {
             enable_write_tools: config.serve.mcp.enable_write_tools,
@@ -199,6 +207,7 @@ fn spawn_mcp_stdio(
     llm_provider: Option<Arc<dyn LlmProvider>>,
     semantic_search: Option<SemanticSearchState>,
     filigree_client: Option<FiligreeHttpClient>,
+    warpline_client: Option<WarplineMcpClient>,
     diagnostics: loomweave_mcp::DiagnosticsContext,
     tool_policy: loomweave_mcp::McpToolPolicy,
     analyze_config_path: Option<PathBuf>,
@@ -215,6 +224,7 @@ fn spawn_mcp_stdio(
                 llm_provider,
                 semantic_search,
                 filigree_client,
+                warpline_client,
                 diagnostics,
                 tool_policy,
                 analyze_config_path,
@@ -234,6 +244,7 @@ fn run_mcp_stdio(
     llm_provider: Option<Arc<dyn LlmProvider>>,
     semantic_search: Option<SemanticSearchState>,
     filigree_client: Option<FiligreeHttpClient>,
+    warpline_client: Option<WarplineMcpClient>,
     diagnostics: loomweave_mcp::DiagnosticsContext,
     tool_policy: loomweave_mcp::McpToolPolicy,
     analyze_config_path: Option<PathBuf>,
@@ -271,6 +282,9 @@ fn run_mcp_stdio(
     if let Some(client) = filigree_client {
         state = state.with_filigree_client(Arc::new(client));
     }
+    if let Some(client) = warpline_client {
+        state = state.with_warpline_client(Arc::new(client));
+    }
     state = state.with_diagnostics(diagnostics);
 
     let serve_result = loomweave_mcp::serve_stdio_with_state_on_runtime(

crates/loomweave-federation/src/config.rs

@@ -550,6 +550,14 @@ impl ClaudePermissionMode {
 #[serde(default, deny_unknown_fields)]
 pub struct IntegrationsConfig {
     pub filigree: FiligreeConfig,
+    /// Warpline (the federation's temporal/change authority) churn-count read,
+    /// consumed at read time by `entity_high_churn_list` /
+    /// `entity_recent_change_list`. Read-only, enrich-only, dependency-sink:
+    /// loomweave never stores a warpline fact (the seam's HARD RULE — loomweave
+    /// retains no cross-run history; see the 2026-06-13 warpline interface lock
+    /// §1, §5). Default disabled — the churn surfaces stay honest-empty with a
+    /// missing-signal note until an operator opts in.
+    pub warpline: WarplineConfig,
 }
 
 #[derive(Debug, Clone, PartialEq, Default, Deserialize)]
@@ -754,6 +762,48 @@ impl Default for FiligreeConfig {
     }
 }
 
+/// Read-time consumption of Warpline's FROZEN churn-count read
+/// (`warpline_entity_churn_count_get`, `warpline.entity_churn_count.v1`). This
+/// is a *read-only* seam: loomweave asks warpline for per-entity change counts
+/// to rank `entity_high_churn_list` / `entity_recent_change_list`, joins them at
+/// read time, and retains NOTHING (the loomweave↔warpline HARD RULE — loomweave
+/// holds no cross-run history). There is deliberately NO write/emit flag here:
+/// unlike the Filigree seam, nothing flows loomweave→warpline.
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize)]
+#[serde(default, deny_unknown_fields)]
+pub struct WarplineConfig {
+    /// Whether the churn surfaces consult warpline. Default `false`: the
+    /// surfaces stay honest-empty (with a missing-signal note naming warpline)
+    /// until an operator opts in. A missing/unreachable warpline with this
+    /// `true` degrades the same way — never an error, never empty-as-clean.
+    pub enabled: bool,
+    /// Operator-configured actor identity. **Reserved, not sent on the wire:**
+    /// `actor` is not in warpline's FROZEN `warpline_entity_churn_count_get`
+    /// schema (`additionalProperties: false`), so the churn read carries none.
+    /// The field is retained (rather than removed) so an existing `loomweave.yaml`
+    /// that sets `integrations.warpline.actor` still parses under
+    /// `deny_unknown_fields` — warpline's own dogfood config sets it.
+    pub actor: String,
+    /// Per-call timeout (seconds) for the warpline churn subprocess round-trip.
+    /// Warpline is an MCP-stdio member (no HTTP read API), launched as a
+    /// subprocess and driven over **newline-delimited** MCP JSON-RPC (the
+    /// transport `warpline-mcp` actually speaks). A warpline child that accepts
+    /// the connection and never answers would otherwise hang the read; this
+    /// bound makes a transport fault degrade to the honest `warpline-unreachable`
+    /// response instead. Default 10s; a `0` is floored to 1s by the client.
+    pub timeout_seconds: u64,
+}
+
+impl Default for WarplineConfig {
+    fn default() -> Self {
+        Self {
+            enabled: false,
+            actor: "loomweave-mcp".to_owned(),
+            timeout_seconds: 10,
+        }
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum ProviderSelection {
     Disabled,

crates/loomweave-federation/src/lib.rs

@@ -6,3 +6,4 @@ pub mod filigree_url;
 pub mod loomweave_port;
 pub mod loomweave_url;
 pub mod scan_results;
+pub mod warpline;