Fix hostid mismatch bug that prevented booting installed systems

Root cause: The `hostid` command returns a value even without /etc/hostid,
but `zgenhostid` generates a DIFFERENT random value. The install script
was calling `hostid` for the GRUB kernel parameter, then later calling
`zgenhostid` to create /etc/hostid - resulting in a mismatch.

ZFS refuses to auto-import pools when spl.spl_hostid doesn't match
/etc/hostid, causing "Failed to mount /sysroot" at boot.

Fix: Generate hostid with zgenhostid FIRST (in configure_bootloader),
then read the consistent value for the GRUB kernel parameter. The
configure_zfs_services function now just copies the already-existing
/etc/hostid to the installed system.

Verified in VM: GRUB and /etc/hostid both show identical values after
installation.

2 files changed, 67 insertions, 32 deletions

diff --git a/custom/install-archzfs b/custom/install-archzfs
index c604868..a6679eb 100755
--- a/custom/install-archzfs
+++ b/custom/install-archzfs
@@ -1071,7 +1071,14 @@ EOF
 configure_bootloader() {
     step "Configuring GRUB Bootloader"
 
-    # Get hostid for kernel parameter
+    # Ensure hostid exists BEFORE reading it
+    # This is critical: hostid command returns a value even without /etc/hostid,
+    # but zgenhostid creates a DIFFERENT value. We must generate first, then read.
+    if [[ ! -f /etc/hostid ]]; then
+        zgenhostid
+    fi
+
+    # Now get the consistent hostid for kernel parameter
     local host_id
     host_id=$(hostid)
 
@@ -1156,13 +1163,8 @@ configure_zfs_services() {
     arch-chroot /mnt systemctl enable zfs-import.target
 
     # Copy hostid to installed system (ZFS uses this for pool ownership)
-    if [[ -f /etc/hostid ]]; then
-        cp /etc/hostid /mnt/etc/hostid
-    else
-        # Generate hostid if it doesn't exist
-        zgenhostid
-        cp /etc/hostid /mnt/etc/hostid
-    fi
+    # Note: hostid is generated in configure_bootloader, so it always exists here
+    cp /etc/hostid /mnt/etc/hostid
 
     # Generate zpool cache
     mkdir -p /mnt/etc/zfs
diff --git a/docs/session-context.org b/docs/session-context.org
index aeaeb02..72ca9b4 100644
--- a/docs/session-context.org
+++ b/docs/session-context.org
@@ -1,35 +1,68 @@
 #+TITLE: Session Context
 #+DATE: 2026-01-19
 
-* Current Session: Monday 2026-01-19 17:29 CST (ongoing)
+* Current Session: Monday 2026-01-19 17:29 CST
 
-** Summary
+** FIXED: Hostid mismatch bug causing boot failures
 
-Continued from interrupted session. Rebuilt ISO with Avahi/hostname fixes, tested successfully, deployed, committed. Verified ratio.local install - no errors.
+*** Problem
+ratio wouldn't boot - dropped to emergency mode with "Failed to mount /sysroot"
+Root account locked in initramfs, preventing debugging.
+
+*** Root Cause
+The install script was generating inconsistent hostids:
+- Line 1076: ~hostid~ command returned value X (used for GRUB cmdline)
+- Line 1163: ~zgenhostid~ created /etc/hostid with value Y
+
+The ~hostid~ command returns a value even without /etc/hostid, but ~zgenhostid~
+generates a DIFFERENT random value. ZFS refused to auto-import the pool because
+the hostids didn't match.
+
+*** Fix Applied (custom/install-archzfs)
+Move ~zgenhostid~ call to configure_bootloader() BEFORE reading hostid:
+
+#+BEGIN_SRC bash
+configure_bootloader() {
+    # Ensure hostid exists BEFORE reading it
+    if [[ ! -f /etc/hostid ]]; then
+        zgenhostid
+    fi
+    # Now get the consistent hostid for kernel parameter
+    local host_id
+    host_id=$(hostid)
+    ...
+}
+#+END_SRC
+
+Simplified configure_zfs_services() to just copy /etc/hostid (always exists now).
+
+*** Verification
+Tested in VM - after installation:
+- GRUB hostid: 073ad2a5
+- /etc/hostid: 073ad2a5
+- MATCH confirmed
+
+*** For ratio
+Needs reinstall with fixed ISO, or manual fix:
+#+BEGIN_SRC bash
+# From live ISO booted on ratio:
+printf '\x56\x19\xc0\xa8' > /mnt/etc/hostid  # 0xa8c01956 in little-endian
+arch-chroot /mnt mkinitcpio -P
+#+END_SRC
+
+** Earlier in Session
+
+- Rebuilt ISO with Avahi/hostname fixes
+- Tested: hostname "archzfs", avahi active, mDNS works
+- Deployed to ~/Downloads/isos/, TrueNAS, USB drives
+- Committed: 0bd172a (Avahi), 4f9eadb (TODO update)
+- Added TODO for Avahi on installed systems
+- Wrote ISO to new 115G flash drive (/dev/sdb)
 
 ** Commits This Session
 
 | Commit | Description |
 |--------|-------------|
 | 0bd172a | Add Avahi mDNS for easy SSH access, fix ISP firmware path |
-
-** What Was Done
-
-1. Recovered from interrupted session
-2. Built ISO with Avahi/hostname fixes
-3. Sanity tests: 13/13 PASSED
-4. Deployed to ~/Downloads/isos/, TrueNAS, USB drive
-5. VM test: hostname "archzfs", avahi active, mDNS working
-6. Committed and pushed
-7. Verified ratio.local install:
-   - ZFS pool ONLINE (mirror, 7.12TB)
-   - All 15 datasets mounted correctly
-   - No failed services
-   - Only benign warnings (RDSEED32, ZFS CDDL taint, amdgpu timeout)
-   - ISP firmware and journald fixes working
-
-** ratio.local Status
-
-- Framework Desktop, AMD Ryzen AI Max 300
-- Kernel 6.12.66-1-lts, ZFS 2.3.3-1
-- Install: SUCCESS, no errors
+| 4f9eadb | Add TODO for Avahi on installed systems, mark live ISO done |
+| PENDING | Fix hostid mismatch bug in install-archzfs |