v0.7.1: walk the ladder once ever — persistent learned modes, rule pins, same-boot iPXE recovery

Answers the operational question 'can a machine try all three boot
binaries in one go?' The protocol can't carry three NBPs in one cycle
(one boot file per DHCP round, the Secure-Boot refusal happens after
handoff with no error report, and the broken-NIC case specifically needs
the firmware itself to load builtin-driver iPXE — GRUB's network rides
the same broken firmware stack). What we CAN do is make the walk a
once-per-machine-ever event and give operators a way to skip it:

- Learned driver modes persist (<work_dir>/driver_modes.json). A MAC
  that reaches the Shim rung, or confirms an iPXE handoff at Builtin,
  is pinned to disk: immune to the 30-min TTL, reloaded at startup.
  The file only carries exceptions — a healthy fleet never writes it.
  Corrupt file starts empty (standard crash-cache policy).
- Boot rules gain an optional driver_mode pin (auto/firmware/builtin/
  shim), consulted by the DHCP proxy BEFORE the escalation ladder:
  'this OUI is a Secure Boot rack -> serve shim immediately' = zero
  failed cycles. Mode-only rules coexist with target rules (a pin
  doesn't shadow a later target match). Editor column on Hosts tab.
- grub.cfg now tries to chainload all-drivers iPXE before showing the
  signed menu: with SB off the chainload succeeds and the client gets
  the full iPXE feature set back in the SAME boot (self-healing for
  mis-escalations, and the handoff then pins the working mode); with
  SB on, shim's verifier refuses it inline — no reboot — and the
  signed menu appears.

DhcpProxyServer now takes the escalation table + rules store from main
(persistence path comes from the configured work dir).

Validation: clippy clean, fmt clean, 299 workspace tests green (+9:
persistence round-trip across restart, Shim pin survives TTL, learned
Builtin survives TTL, corrupt-file recovery, default-mode-never-
persisted, rule-pin matching incl. unknown-mode tolerance and
pin/target coexistence, GRUB chainload-before-menu ordering, API
round-trip of the driver_mode field).

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

crates/http-api/src/grub_script.rs

@@ -35,6 +35,24 @@ pub fn render_grub_menu(isos: &[IsoMeta], base_url: &str) -> String {
     let dev = grub_http_device(base);
     let mut s = String::new();
     let _ = writeln!(s, "# OpenPXE — Secure Boot menu (signed shim+GRUB chain)");
+    // v0.7.1: before showing the limited signed menu, try to hand the
+    // boot back to full iPXE *in this same boot cycle*. With Secure Boot
+    // OFF the chainload succeeds and the client gets the complete iPXE
+    // feature set (sanboot, wimboot, the full menu) despite having been
+    // escalated here. With Secure Boot ON, shim's verifier refuses the
+    // unsigned image INLINE — no reboot, no failed cycle — and execution
+    // falls through to the signed menu below. The all-drivers build is
+    // used because a MAC only lands here after the firmware-net build
+    // already failed once.
+    let _ = writeln!(s, "if [ \"$grub_cpu\" = \"arm64\" ]; then");
+    let _ = writeln!(s, "    set openpxe_ipxe=ipxe-arm64.efi");
+    let _ = writeln!(s, "else");
+    let _ = writeln!(s, "    set openpxe_ipxe=ipxe.efi");
+    let _ = writeln!(s, "fi");
+    let _ = writeln!(s, "if chainloader {dev}/ipxe/$openpxe_ipxe ; then");
+    let _ = writeln!(s, "    boot");
+    let _ = writeln!(s, "fi");
+    let _ = writeln!(s);
     let _ = writeln!(s, "set timeout=30");
     let _ = writeln!(s, "set default=0");
     let _ = writeln!(s);
@@ -139,6 +157,24 @@ mod tests {
         assert!(cfg.contains("Boot from local disk"), "{cfg}");
     }
 
+    #[test]
+    fn config_tries_ipxe_chainload_before_menu() {
+        // v0.7.1: SB-off machines recover full iPXE in the same boot;
+        // SB-on machines fail the chainload inline and reach the menu.
+        let cfg = render_grub_menu(&[linux_iso()], "http://10.0.0.5:8080");
+        let chain_pos = cfg
+            .find("if chainloader (http,10.0.0.5:8080)/ipxe/$openpxe_ipxe ; then")
+            .expect("chainload attempt missing");
+        let menu_pos = cfg.find("menuentry").expect("menu missing");
+        assert!(
+            chain_pos < menu_pos,
+            "chainload must precede the menu:\n{cfg}"
+        );
+        // Arch-conditional binary selection via GRUB's $grub_cpu.
+        assert!(cfg.contains("set openpxe_ipxe=ipxe-arm64.efi"), "{cfg}");
+        assert!(cfg.contains("set openpxe_ipxe=ipxe.efi"), "{cfg}");
+    }
+
     #[test]
     fn sanboot_and_wimboot_entries_are_omitted() {
         let mut iso = linux_iso();

crates/http-api/tests/full_flow.rs

@@ -2751,3 +2751,23 @@ async fn arch_selective_rule_ignores_other_arches() {
     assert_eq!(s, StatusCode::OK);
     assert!(String::from_utf8_lossy(&b).contains("boot rule -> fake-alpine-linux"));
 }
+
+#[tokio::test]
+async fn boot_rule_driver_mode_pin_round_trips_via_api() {
+    // v0.7.1: a rule may pin only a boot binary (no target) — the API
+    // must persist and return it for the DHCP proxy to consult.
+    let (state, _dir) = build_state().await;
+    let app = build_router(state.clone());
+    let cfg = r#"{"rules":[{"mac_prefix":"aa:bb:cc","arch":"","target":"","driver_mode":"shim","enabled":true,"note":"SB rack"}],"webhook_url":""}"#;
+    let (s, _) = put_json(&app, "/api/boot-rules", cfg).await;
+    assert_eq!(s, StatusCode::NO_CONTENT);
+    let (s, b) = get(&app, "/api/boot-rules").await;
+    assert_eq!(s, StatusCode::OK);
+    let v: serde_json::Value = serde_json::from_slice(&b).unwrap();
+    assert_eq!(v["rules"][0]["driver_mode"], "shim");
+    // And the store the DHCP proxy shares resolves the pin.
+    assert_eq!(
+        state.boot_rules.driver_mode_hint("aa:bb:cc:00:00:07", None),
+        Some(openpxe_core::DriverMode::Shim)
+    );
+}