Keep builds on the bus under their module, so no lookup reads the bucket whole (issue 1121, ADR 0427)

Milestone 5 moved 8,599 build records onto the bus under bare build ids, each
carrying its module's whole manifest. Every build lookup then read the whole
bucket, and a delivery plan's send did that per module per machine while it
held the plans and the machine's declaration: the send of build-agent never
finished, and every other act and the status waited behind it.

Builds now live under <module>.build.<id> (requests under req.<id>, id.<id>
names a build's module), with pointer keys newest, worked, held,
commit.<sha> and source.<reuse key> that move only to a newer build and are
read as hints, repaired when wrong. Manifests are kept once in the same
bucket under manifest.sha256-<hex>, so no grant the running bus lacks is
needed. The old keys are laid out once at start, idempotently, and left
unread. The calls a plan look makes on the silent clocks while it holds the
plans are bounded, since the vendored kv.Keys ignores its context.

internal/inventory/source.go

@@ -3,6 +3,8 @@ package inventory
 import (
 	"context"
 	"encoding/json"
+
+	"github.com/novox/mesh-controller/internal/chain"
 )
 
 // A build whose source is unchanged is never a move (novox/hq issue 280).
@@ -26,6 +28,7 @@ type sourceRow struct {
 	id, commit, fingerprint string
 	made                    []byte
 	manifest                []byte
+	manifestDigest          string
 	failedGate              bool
 }
 
@@ -97,6 +100,15 @@ func (i *Inventory) StandingBuild(ctx context.Context, module, build string) (st
 	for k, b := range builds {
 		if b.id == build {
 			s := builds[standing(builds, k)]
+			if len(s.manifest) == 0 && s.manifestDigest != "" {
+				// The manifest is kept apart from the record (issue 1121): one Get.
+				c, on, err := i.ChainReads(ctx, KindBuilds)
+				if err != nil || !on {
+					return "", nil, err
+				}
+				raw, err := manifestOfRecord(ctx, c, chain.Build{ID: s.id, ManifestDigest: s.manifestDigest})
+				return s.id, raw, err
+			}
 			return s.id, s.manifest, nil
 		}
 	}
@@ -106,6 +118,12 @@ func (i *Inventory) StandingBuild(ctx context.Context, module, build string) (st
 // SourceFingerprints is, per module, per commit, the source fingerprint of the newest successful build
 // from it that has one: module → commit → fingerprint. A commit whose builds carry none is absent.
 func (i *Inventory) SourceFingerprints(ctx context.Context) (map[string]map[string]string, error) {
+	if c, on, err := i.ChainReads(ctx, KindBuilds); err != nil {
+		return nil, err
+	} else if on {
+		// Read from the commit pointers, which carry each commit's source fingerprint: no record is read (issue 1121).
+		return i.chainSourceFingerprints(ctx, c)
+	}
 	all, _, err := i.sourceRows(ctx, "")
 	if err != nil {
 		return nil, err
@@ -129,6 +147,12 @@ func (i *Inventory) SourceFingerprints(ctx context.Context) (map[string]map[stri
 
 // BuildSourceFingerprints is SourceFingerprints for one module: commit → fingerprint.
 func (i *Inventory) BuildSourceFingerprints(ctx context.Context, module string) (map[string]string, error) {
+	if c, on, err := i.ChainReads(ctx, KindBuilds); err != nil {
+		return nil, err
+	} else if on {
+		// This module's commit pointers only (issue 1121).
+		return i.chainBuildSourceFingerprints(ctx, c, module)
+	}
 	all, err := i.SourceFingerprints(ctx)
 	if err != nil {
 		return nil, err
@@ -142,6 +166,11 @@ func (i *Inventory) BuildSourceFingerprints(ctx context.Context, module string)
 // heldMade is, per module, what the build standing for its newest successful build made — what Held
 // answers (novox/hq issue 280).
 func (i *Inventory) heldMade(ctx context.Context) (map[string][]Artifact, error) {
+	if c, on, err := i.ChainReads(ctx, KindBuilds); err != nil {
+		return nil, err
+	} else if on {
+		return i.chainHeldMade(ctx, c)
+	}
 	all, _, err := i.sourceRows(ctx, "")
 	if err != nil {
 		return nil, err