cmd/mesh-host/main.go

@@ -8,7 +8,9 @@ package main
 
 import (
 	"context"
+	"crypto/sha256"
 	"encoding/base64"
+	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"flag"
@@ -734,7 +736,7 @@ func applyAndKeep(ctx context.Context, opts options, raw []byte, signed *store.D
 			saveErr.Error()}
 	}
 
-	report := link.Report{Carried: carriedPorts(updated)}
+	report := link.Report{Carried: carriedPorts(updated), Declared: digestOf(raw)}
 	for _, change := range outcome.Outcomes {
 		report.Applied = append(report.Applied, change.ID)
 	}
@@ -809,6 +811,14 @@ func sealOpener(statePath string) apply.Unseal {
 //
 // Only what was carried. What the mesh itself put here it already knows about, and reporting it
 // back would make the machine an authority on the mesh's own bookkeeping.
+// digestOf names a declaration by its bytes, exactly as the mesh names what it sends. The two
+// sides never exchange the digest of different things: this hashes the same raw bytes the mesh
+// hashed when it recorded the send.
+func digestOf(body []byte) string {
+	sum := sha256.Sum256(body)
+	return hex.EncodeToString(sum[:])
+}
+
 func carriedPorts(state store.State) []int {
 	seen := map[int]bool{}
 	var out []int

internal/link/messages.go

@@ -67,4 +67,14 @@ type Report struct {
 	// A node *states* and the mesh writes, which is the whole shape of this message: this is the
 	// machine saying what is true of it, not asking for anything.
 	Carried []int `json:"carried,omitempty"`
+
+	// Declared is the digest of the declaration this report is about — sha256 of the exact bytes
+	// the mesh sent, which the mesh recorded when it sent them.
+	//
+	// **Which declaration, not when.** The mesh compared its send time to this report's arrival
+	// to decide whether a machine had caught up, and lost the race it invited: an apply started
+	// under the previous declaration finishes after the next one is sent, its report lands newer
+	// than the send, and the machine reads as caught up with words it has not read yet. Clocks
+	// cannot answer "which"; the digest is the answer itself.
+	Declared string `json:"declared,omitempty"`
 }