split render_flake into per-section helpers; no runtime change

Pure refactor of hive-meta-flake: render_flake now calls one helper per section of the flake, so the too_many_lines allow is gone. The rendered text is unchanged.

hive-meta-flake/src/lib.rs

@@ -173,19 +173,25 @@ pub fn canonical_inputs_in_lock(raw: &str) -> Vec<&'static str> {
 /// Render the meta flake. `vars` are the [`FORWARDED_VARS`] pairs with a
 /// value; `github_disabled` turns the agents' GitHub integration off. Errors
 /// on a custom agent without an [`AgentPin`].
-#[allow(
-    clippy::too_many_lines,
-    reason = "templated string-builder for the meta flake — the length is one \
-              contiguous fmt block, splitting it would just hide the shape"
-)]
 pub fn render_flake(
     hyperhive_url: &str,
     agents: &[AgentSpec],
     vars: &[(&'static str, String)],
     github_disabled: bool,
 ) -> Result<String> {
-    use std::fmt::Write as _;
     let mut out = String::new();
+    push_inputs(&mut out, hyperhive_url, agents)?;
+    push_mk_agent_open(&mut out);
+    push_agent_service_options(&mut out, vars, github_disabled);
+    push_agent_environment(&mut out, vars);
+    push_agent_entries(&mut out, agents);
+    Ok(out)
+}
+
+/// The flake header and `inputs` block: `hyperhive`, `nixpkgs`, and one input
+/// per config-repo agent.
+fn push_inputs(out: &mut String, hyperhive_url: &str, agents: &[AgentSpec]) -> Result<()> {
+    use std::fmt::Write as _;
     out.push_str("{\n  description = \"hyperhive deployed agents\";\n  inputs = {\n");
     // `hyperhive` is pinned by forge URL and rev, so the flake resolves on
     // any machine that can reach the forge. `nixpkgs` follows hyperhive's
@@ -230,6 +236,12 @@ pub fn render_flake(
             );
         }
     }
+    Ok(())
+}
+
+/// Closes `inputs`, opens `outputs` and the `mkAgent` function up to the
+/// start of the per-agent module.
+fn push_mk_agent_open(out: &mut String) {
     out.push_str(
         "  };\n  outputs =\n    { self, hyperhive, ... }@inputs:\n    let\n      mkAgent = { name, port, archetype ? null }:\n",
     );
@@ -254,6 +266,14 @@ pub fn render_flake(
             {
 "#,
     );
+}
+
+/// Service URL options and the GitHub override inside the per-agent module.
+fn push_agent_service_options(
+    out: &mut String,
+    vars: &[(&'static str, String)],
+    github_disabled: bool,
+) {
     // Agent-facing service URLs (`services.hyperhive.agent.forge.url`, `services.hyperhive.agent.matrix.url`):
     // emit the host's real values as build-time agent config, the same
     // host-state -> agent-module shape as the CA block above.
@@ -279,7 +299,7 @@ pub fn render_flake(
     // the forge, which a running hive always has, so the caller rejects a
     // missing `HIVE_FORGE_URL` before it renders. The check is not here because
     // rendering is a pure string operation the tests exercise directly.
-    push_forwarded_var_options(&mut out, vars);
+    push_forwarded_var_options(out, vars);
     // GitHub integration is on by default in every agent
     // (`services.hyperhive.agent.github.enable`); the host turns it off swarm-wide via
     // `services.hyperhive.swarm.github.enable = false`, passed here as
@@ -288,6 +308,12 @@ pub fn render_flake(
     if github_disabled {
         out.push_str("              services.hyperhive.agent.github.enable = false;\n");
     }
+}
+
+/// The rest of the per-agent module: user, hostname, git identity, and the
+/// container-wide and harness-service environments.
+fn push_agent_environment(out: &mut String, vars: &[(&'static str, String)]) {
+    use std::fmt::Write as _;
     out.push_str(
         r#"              # The harness service inside the container runs as a
               # non-root unix user named after the agent (`damocles`,
@@ -374,6 +400,11 @@ pub fn render_flake(
       nixosConfigurations = {
 "#,
     );
+}
+
+/// One `mkAgent` line per agent, closing `outputs`.
+fn push_agent_entries(out: &mut String, agents: &[AgentSpec]) {
+    use std::fmt::Write as _;
     for spec in agents {
         // `source` and `name` are identifiers (`archetypes::store_read`), so
         // they need no escaping.
@@ -390,7 +421,6 @@ pub fn render_flake(
         );
     }
     out.push_str("      };\n    };\n}\n");
-    Ok(out)
 }
 
 /// Web UI port range, shared by every agent including the manager.