fix(history): raise authoritative graph limit to 5 GiB

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## Unreleased
 
+- Raise the immutable-history aggregate authoritative-evidence limit from
+  512 MiB to 5 GiB so large repositories can publish, validate, and compare
+  complete realizations while retaining the existing per-record and record-count
+  bounds.
+
 - Make `compass review` text and Markdown easier to scan by shortening commit
   and report references, using plain-language status labels, and summarizing
   witness relationships without printing opaque graph-node IDs. Canonical JSON

COMPATIBILITY.md

@@ -94,6 +94,14 @@ history profiles, and cache identities.
 
 ## Evolving contracts
 
+Immutable history now accepts up to 5 GiB of aggregate authoritative key and
+value bytes per realization, raised from 512 MiB. The history schema and
+canonical encoding are unchanged, as are the per-key, per-value, per-tree,
+JSON-depth, job, and diagnostic bounds. Readers from older Compass releases
+continue to reject a realization whose authoritative content exceeds 512 MiB;
+deploy a reader containing this limit widening before sharing larger
+realizations.
+
 The closed route-stage vocabulary used by `compass.graph/1`,
 `compass.query/1`, and `compass.framework-context/1` now includes the additive
 `dependency` and `security` values. The query contract manifest and fingerprint

crates/compass-history/src/validate.rs

@@ -12,7 +12,7 @@ use crate::{
 
 type Records = Vec<(Vec<u8>, Vec<u8>)>;
 
-pub const MAX_AUTHORITATIVE_BYTES: u64 = 512 * 1024 * 1024;
+pub const MAX_AUTHORITATIVE_BYTES: u64 = 5 * 1024 * 1024 * 1024;
 pub const MAX_KEY_BYTES: usize = 1024 * 1024;
 pub const MAX_RECORD_VALUE_BYTES: usize = 64 * 1024 * 1024;
 pub const MAX_RECORDS_PER_TREE: u64 = 10_000_000;
@@ -594,6 +594,12 @@ mod tests {
         }
     }
 
+    #[test]
+    fn authoritative_history_limit_is_five_gibibytes() {
+        assert_eq!(MAX_AUTHORITATIVE_BYTES, 5_368_709_120);
+        assert!(!exceeds_limit(616_211_608, MAX_AUTHORITATIVE_BYTES));
+    }
+
     #[test]
     fn repeated_resource_limit_failures_collapse_to_the_largest_observation() {
         let mut problems = Vec::new();

docs/guides/versioned-history.md

@@ -403,6 +403,12 @@ Export equivalence is semantic and canonical. JSON object or record ordering
 that does not affect meaning is not a contract; graph structure, attributes,
 multiplicity, duplicate id-less hyperedges, and authoritative bytes are.
 
+Each immutable realization accepts at most 5 GiB of aggregate authoritative
+key and value bytes. Per-record and record-count limits remain independently
+enforced, and crossing any limit fails publication rather than exposing a
+partial realization. Compass releases with the former 512 MiB ceiling cannot
+read a realization above that older bound.
+
 ## 8. Choose a preferred realization
 
 When a commit has multiple valid realizations: