From 44eabcccb20dac61ddb0708c9408e9b0dd96b96a Mon Sep 17 00:00:00 2001
From: callumalpass <callumalpass@gmail.com>
Date: Thu, 6 Aug 2026 16:25:31 +1000
Subject: [PATCH] Define collection authority timezone configuration

---
 04-configuration.md             | 9 +++++++++
 schemas/v0.3/config.schema.json | 5 +++++
 2 files changed, 14 insertions(+)

diff --git a/04-configuration.md b/04-configuration.md
index 607537a..5cc7e0b 100644
--- a/04-configuration.md
+++ b/04-configuration.md
@@ -17,6 +17,7 @@ Recommended config:
 spec_version: "0.3.0"
 
 settings:
+  timezone: Australia/Melbourne
   types_folder: _types
   contracts_folder: _contracts
   record_extensions: [md]
@@ -37,6 +38,7 @@ Pre-1.0 draft versions MAY be accepted by explicit compatibility setting.
 
 | Key | Type | Default | Meaning |
 | --- | --- | --- | --- |
+| `settings.timezone` | string | local runtime | durable IANA timezone for authority-owned calendar semantics |
 | `settings.types_folder` | string | `_types` | folder containing type files |
 | `settings.contracts_folder` | string | `_contracts` | folder containing data contract files |
 | `settings.record_extensions` | list of strings | `[md]` | record file extensions without dot |
@@ -49,6 +51,13 @@ Pre-1.0 draft versions MAY be accepted by explicit compatibility setting.
 `settings.explicit_type_keys` replaces the default key list. An empty list makes
 all type membership inferred.
 
+`settings.timezone`, when present, MUST be an IANA timezone identifier. `UTC`
+is the canonical identifier for Coordinated Universal Time. Numeric offsets and
+ambient aliases such as `local` are invalid because they do not name a durable
+calendar authority or model daylight-saving transitions. An invalid configured
+timezone makes the collection configuration invalid; an implementation MUST
+NOT silently substitute its runtime timezone.
+
 The types and contracts folders MUST be different normalized paths. Both are
 reserved control-file folders and are excluded from ordinary record discovery.
 
diff --git a/schemas/v0.3/config.schema.json b/schemas/v0.3/config.schema.json
index 3fd5e99..7ed3506 100644
--- a/schemas/v0.3/config.schema.json
+++ b/schemas/v0.3/config.schema.json
@@ -20,6 +20,11 @@
     "settings": {
       "type": "object",
       "properties": {
+        "timezone": {
+          "type": "string",
+          "minLength": 1,
+          "description": "Durable IANA timezone for collection-authority calendar semantics"
+        },
         "types_folder": {
           "type": "string",
           "minLength": 1