From 7c5bdcd004f3cc3aebc46e5911f5814552778c5d Mon Sep 17 00:00:00 2001
From: matthew-pilot <matthew@vulturelabs.io>
Date: Thu, 18 Jun 2026 12:57:44 +0000
Subject: [PATCH] docs: add version compatibility table to SPEC.md (PILOT-421)
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Add a version compatibility table after the title block mapping each
SPEC document revision (v0.1–v0.5) to the corresponding Pilot Protocol
release series and protocol version number. This gives implementors a
quick reference for which spec version aligns with which daemon release.

- Summary header block showing the current spec/protocol version
- Compatibility table: SPEC version → protocol version → first release → status
- Note explaining the relationship between SPEC version and protocol version fields

Closes PILOT-421
---
 SPEC.md | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/SPEC.md b/SPEC.md
index 8b9610f..2d6c37f 100644
--- a/SPEC.md
+++ b/SPEC.md
@@ -1,5 +1,22 @@
 # Pilot Protocol Wire Specification v0.5
 
+> **Specification version:** v0.5  
+> **Protocol version (header):** `1` (4-bit field, see §3.2)
+
+## Version Compatibility
+
+| SPEC Version | Protocol version | First Pilot Protocol Release | Status |
+|---|---|---|---|
+| v0.5 | 1 | v1.10.0 | ✅ Active (current) |
+| v0.4 | 1 | v1.7.0 | ⏳ Historical |
+| v0.3 | 1 | v1.5.0 | ⏳ Historical |
+| v0.2 | 1 | v1.4.0 | ⏳ Historical |
+| v0.1 | 1 | v1.0.0 | ⏳ Historical |
+
+> **Note:** The **SPEC version** tracks the wire specification document. The 4-bit **Protocol version** field in the packet header (§3.2) identifies the wire format itself and has remained `1` across all v0.x spec revisions — the wire format is backward-compatible within the same protocol version number. A future spec revision that changes the wire format will increment this field.
+
+---
+
 ## 1. Addressing
 
 ### 1.1 Virtual Address Format