diff --git a/hive-c0re/src/meta.rs b/hive-c0re/src/meta.rs
index 611c48f8..6fe93fcf 100644
--- a/hive-c0re/src/meta.rs
+++ b/hive-c0re/src/meta.rs
@@ -333,24 +333,27 @@ where
     use std::fmt::Write as _;
     let mut out = String::new();
     out.push_str("{\n  description = \"hyperhive deployed agents\";\n  inputs = {\n");
-    // hyperhive's own flake.nix is the single channel-pin authority
-    // (closes #526). meta declares `nixpkgs` + `nixpkgs-unstable` as
-    // aliases for hyperhive's sub-inputs via `follows`, so every
-    // agent-level `inputs.<X>.inputs.nixpkgs.follows = "nixpkgs"`
-    // directive resolves transitively to hyperhive's pin. One
-    // channel decision in the whole tree, no second source to drift.
+    // Pin canonical nixpkgs revisions at the meta level so every input
+    // that pulls a nixpkgs sub-input can `follows = "nixpkgs"` and
+    // collapse to one shared node (closes #317). hyperhive's own
+    // flake.nix picks `nixos-26.05`; we mirror that here so meta and
+    // hyperhive don't diverge into two stable channels by default.
+    // Operator can override these at the meta layer to slide every
+    // dependent agent onto a different channel in one move.
     //
-    // Operators who want to slide the whole swarm onto a different
-    // channel do it at the host level via
-    // `inputs.hyperhive.inputs.nixpkgs.follows = "nixpkgs"`, which
-    // makes hyperhive's nixpkgs = the host's nixpkgs and cascades
-    // through to every agent. (closes #317 also stays satisfied —
-    // `nixpkgs` is still a single canonical name in the meta tree,
-    // it just resolves through hyperhive instead of being its own
-    // root input.)
+    // Keeping the URL concrete (rather than `follows = "hyperhive/nixpkgs"`)
+    // is intentional per mara on #619: a configuring agent needs the
+    // url present in the rendered meta flake so it can eval against
+    // it — `follows` requires resolving through hyperhive, which
+    // breaks standalone eval workflows the agent + manager rely on.
+    out.push_str("    nixpkgs.url = \"github:NixOS/nixpkgs/nixos-26.05\";\n");
+    out.push_str("    nixpkgs-unstable.url = \"github:NixOS/nixpkgs/nixpkgs-unstable\";\n");
     let _ = writeln!(out, "    hyperhive.url = \"{hyperhive_flake}\";");
-    out.push_str("    nixpkgs.follows = \"hyperhive/nixpkgs\";\n");
-    out.push_str("    nixpkgs-unstable.follows = \"hyperhive/nixpkgs-unstable\";\n");
+    // Collapse hyperhive's own `nixpkgs` + `nixpkgs-unstable` inputs
+    // into meta's. Without this, hyperhive's flake.nix declarations
+    // become independent `nixpkgs_N` nodes in meta/flake.lock.
+    out.push_str("    hyperhive.inputs.nixpkgs.follows = \"nixpkgs\";\n");
+    out.push_str("    hyperhive.inputs.nixpkgs-unstable.follows = \"nixpkgs-unstable\";\n");
     for spec in agents {
         let _ = writeln!(
             out,
@@ -566,7 +569,7 @@ mod tests {
     }
 
     #[test]
-    fn render_flake_aliases_nixpkgs_to_hyperhive() {
+    fn render_flake_declares_canonical_nixpkgs() {
         let out = render_flake(
             "github:example/hyperhive",
             8000,
@@ -574,24 +577,30 @@ mod tests {
             &std::collections::HashMap::new(),
             &[sample_spec("alice", false, 9001)],
         );
-        // Meta's `nixpkgs` + `nixpkgs-unstable` are aliases for
-        // hyperhive's sub-inputs (closes #526). Single channel-pin
-        // authority: hyperhive's own flake.nix.
-        assert!(
-            out.contains("nixpkgs.follows = \"hyperhive/nixpkgs\""),
-            "missing nixpkgs follows alias:\n{out}"
-        );
-        assert!(
-            out.contains("nixpkgs-unstable.follows = \"hyperhive/nixpkgs-unstable\""),
-            "missing nixpkgs-unstable follows alias:\n{out}"
-        );
-        // And conversely: no literal channel ref baked in. If this
-        // assertion fails, someone reintroduced a hardcoded ref —
-        // see #526 for why that drifts.
-        assert!(
-            !out.contains("nixpkgs.url ="),
-            "no literal `nixpkgs.url` should be emitted (hyperhive owns the pin):\n{out}"
+        // Top-level nixpkgs inputs pinned by meta — every nested
+        // nixpkgs input can follow these instead of resolving its own
+        // (closes #317). Concrete URL (not `follows = "hyperhive/nixpkgs"`)
+        // per mara on #619 — a configuring agent needs the URL to
+        // resolve when evaluating meta standalone.
+        assert!(out.contains("nixpkgs.url = \"github:NixOS/nixpkgs/nixos-26.05\""));
+        assert!(out.contains("nixpkgs-unstable.url = \"github:NixOS/nixpkgs/nixpkgs-unstable\""));
+    }
+
+    #[test]
+    fn render_flake_collapses_hyperhive_nixpkgs_via_follows() {
+        let out = render_flake(
+            "github:example/hyperhive",
+            8000,
+            "she/her",
+            &std::collections::HashMap::new(),
+            &[],
         );
+        // hyperhive's own `nixpkgs` + `nixpkgs-unstable` declarations
+        // get redirected at meta's. Without these, meta/flake.lock
+        // ends up with separate `nixpkgs_N` nodes for hyperhive's
+        // copy (the pre-#317 status quo).
+        assert!(out.contains("hyperhive.inputs.nixpkgs.follows = \"nixpkgs\""));
+        assert!(out.contains("hyperhive.inputs.nixpkgs-unstable.follows = \"nixpkgs-unstable\""));
     }
 
     #[test]