From e54fda40d73fc0058e21d30a5f50d61e069b3b39 Mon Sep 17 00:00:00 2001
From: igneum-labs <337424239+igneum-labs@users.noreply.github.com>
Date: Wed, 7 Oct 2026 18:12:00 +0000
Subject: [PATCH] fast-time: switch-crossing.mjs drops null override fields at
 write (an older binary refuses an unknown key)

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
---
 infra/fast-time/switch-crossing.mjs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/infra/fast-time/switch-crossing.mjs b/infra/fast-time/switch-crossing.mjs
index d6cb4b9a9..b2f560597 100644
--- a/infra/fast-time/switch-crossing.mjs
+++ b/infra/fast-time/switch-crossing.mjs
@@ -52,7 +52,10 @@ function mergeOverrideText(text, fields) {
   let out = text;
   for (const k of Object.keys(fields)) out = out.replace(new RegExp(`\\s*"${k}":\\s*[^,}\\n]+,?`), '');
   const extra = Object.entries(fields).map(([k, v]) => `"${k}": ${typeof v === 'string' && !/^\d+$/.test(v) ? JSON.stringify(v) : v}`).join(', ');
-  return out.replace(/,?\s*}\s*$/, `,\n  ${extra}\n}\n`);
+  out = out.replace(/,?\s*}\s*$/, `,\n  ${extra}\n}\n`);
+  // a null field is an unset Option and means the same as an absent one, but a binary older than the field refuses the
+  // unknown key (deny_unknown_fields): the 0.3.22 pair exited on the 0.3.23 line's subsidy_per_block field, 18:09Z
+  return out.replace(/\n\s*"[a-z0-9_]+":\s*null\s*,?/g, '').replace(/,(\s*})/g, '$1');
 }
 const DAY_MS = fieldOf('pow_day_ms');
 const common = { genesis_bits: GENESIS_BITS, skip_proof_of_work: false, program_class_v3_activation_daa: NEVER, program_class_v4_activation_daa: NEVER, signing_bonus_activation_daa: NEVER };