diff --git a/ingestion/cmd/server/main.go b/ingestion/cmd/server/main.go
index a91a961..f513463 100644
--- a/ingestion/cmd/server/main.go
+++ b/ingestion/cmd/server/main.go
@@ -16,6 +16,10 @@ import (
 
 	"github.com/mathiasbq/hyperguild/ingestion/internal/api"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/claudewatcher"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/audit"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/capture"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/capturehttp"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/classification"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/embed"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/gitea"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/graphstore"
@@ -119,6 +123,18 @@ func envInt(key string, fallback int) int {
 	return fallback
 }
 
+// splitList parses a comma-separated env value into a trimmed,
+// empty-free slice. Used for the capture sovereign-principal allowlist.
+func splitList(v string) []string {
+	var out []string
+	for _, p := range strings.Split(v, ",") {
+		if p = strings.TrimSpace(p); p != "" {
+			out = append(out, p)
+		}
+	}
+	return out
+}
+
 // systemHostname returns os.Hostname() with a "unknown" fallback so the
 // caller never has to handle the rare error path.
 func systemHostname() string {
@@ -349,6 +365,30 @@ func main() {
 
 	mux.Handle("/mcp", chassisauth.BearerMiddleware(mcpToken, jwtValidator, "brain", resourceMetadataURL, mcpSrv))
 
+	// POST /capture (#53): the uniform capture REST door. Needs a ticket
+	// tracker to file action items, so it only mounts when Gitea is
+	// configured. It reuses the MCP server's graph-wired brain store (one
+	// implementation), the classification tags for the I1 gate, and a slog
+	// audit sink (the loki+buffer sink lands in #54). The handler does its
+	// own auth (static + JWT) because it needs the principal to derive the
+	// trust-zone origin — the chassis middleware hides it.
+	if tracker := mcpSrv.IssueTracker(); tracker != nil {
+		classCfg, cerr := classification.Load(brainDir)
+		if cerr != nil {
+			logger.Error("load classification config", "err", cerr)
+			os.Exit(1)
+		}
+		captureSvc := capture.NewService(
+			mcpSrv.BrainStore(), tracker, nil, classCfg, audit.NewSlogSink(logger))
+		sovereign := splitList(os.Getenv("BRAIN_CAPTURE_SOVEREIGN_PRINCIPALS"))
+		captureH := capturehttp.New(captureSvc, jwtValidator, mcpToken, "local-cli",
+			capturehttp.NewOriginResolver(sovereign))
+		mux.Handle("POST /capture", captureH)
+		logger.Info("capture endpoint enabled", "sovereign_principals", len(sovereign))
+	} else {
+		logger.Info("capture endpoint disabled (BRAIN_GITEA_TOKEN unset)")
+	}
+
 	// Opt-in OAuth 2.0 client_credentials flow for claude.ai's custom-MCP
 	// integration UI, which has no static-Bearer field. Setting both
 	// OAUTH_CLIENT_ID and OAUTH_CLIENT_SECRET enables the token exchange;
diff --git a/ingestion/internal/audit/slog.go b/ingestion/internal/audit/slog.go
new file mode 100644
index 0000000..b7d57d2
--- /dev/null
+++ b/ingestion/internal/audit/slog.go
@@ -0,0 +1,48 @@
+// Package audit provides AuditSink implementations for the capture
+// capability (I5). This file ships the minimal slog-backed sink used in
+// #53: it emits the request-level audit record to structured logs, which
+// the alloy/loki substrate already scrapes. The classification-aware
+// degradation/refusal sink (confidential fails closed, internal buffers +
+// reconciles) lands in #54 and replaces this behind the same interface.
+package audit
+
+import (
+	"context"
+	"log/slog"
+
+	"github.com/mathiasbq/hyperguild/ingestion/internal/capture"
+)
+
+// SlogSink records audit entries to an slog.Logger. It never fails, so it
+// does not exercise the I5 floor (refuse-if-unauditable) — that is #54's
+// loki+buffer sink. A nil logger falls back to slog.Default().
+type SlogSink struct {
+	logger *slog.Logger
+}
+
+// NewSlogSink constructs a SlogSink. nil logger ⇒ slog.Default().
+func NewSlogSink(logger *slog.Logger) *SlogSink {
+	if logger == nil {
+		logger = slog.Default()
+	}
+	return &SlogSink{logger: logger}
+}
+
+// Record emits the audit entry at info level. Security events, when
+// present, are logged at warn level so they surface independently of the
+// routine audit stream.
+func (s *SlogSink) Record(_ context.Context, e capture.AuditEntry) error {
+	s.logger.Info("capture audit",
+		"principal", e.Principal,
+		"actor", e.Actor,
+		"harness", e.Harness,
+		"session_ref", e.SessionRef,
+		"classification", e.EffectiveClassification,
+		"items", e.Items,
+		"ts", e.Timestamp,
+	)
+	for _, ev := range e.SecurityEvents {
+		s.logger.Warn("capture security event", "principal", e.Principal, "event", ev)
+	}
+	return nil
+}
diff --git a/ingestion/internal/audit/slog_test.go b/ingestion/internal/audit/slog_test.go
new file mode 100644
index 0000000..687528d
--- /dev/null
+++ b/ingestion/internal/audit/slog_test.go
@@ -0,0 +1,41 @@
+package audit_test
+
+import (
+	"bytes"
+	"context"
+	"log/slog"
+	"testing"
+
+	"github.com/mathiasbq/hyperguild/ingestion/internal/audit"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/capture"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSlogSinkRecordsEntryAndSecurityEvents(t *testing.T) {
+	var buf bytes.Buffer
+	sink := audit.NewSlogSink(slog.New(slog.NewTextHandler(&buf, nil)))
+
+	err := sink.Record(context.Background(), capture.AuditEntry{
+		Principal:               "koala-cli",
+		Harness:                 "claude-code",
+		EffectiveClassification: "confidential",
+		Items:                   []string{"insight:wiki/a/facts/x.md"},
+		SecurityEvents:          []string{"asserted-vs-derived origin mismatch"},
+	})
+	require.NoError(t, err)
+
+	out := buf.String()
+	assert.Contains(t, out, "capture audit")
+	assert.Contains(t, out, "koala-cli")
+	assert.Contains(t, out, "confidential")
+	assert.Contains(t, out, "capture security event")
+	assert.Contains(t, out, "asserted-vs-derived origin mismatch")
+}
+
+func TestSlogSinkNilLoggerDefaults(t *testing.T) {
+	// nil logger must not panic.
+	require.NotPanics(t, func() {
+		_ = audit.NewSlogSink(nil).Record(context.Background(), capture.AuditEntry{})
+	})
+}
diff --git a/ingestion/internal/capture/entities.go b/ingestion/internal/capture/entities.go
index 05f295d..c9aa227 100644
--- a/ingestion/internal/capture/entities.go
+++ b/ingestion/internal/capture/entities.go
@@ -15,13 +15,44 @@
 // (stricter wins), best-effort orchestration, and the partial receipt.
 package capture
 
+// Zone is the trust zone a capture originates from, server-derived from
+// the authenticated principal (spec §4.2 / I1). It is NEVER taken from
+// caller input — context.Harness is descriptive telemetry only.
+type Zone int
+
+const (
+	// ZoneUnknown means the origin was not set. The REST adapter always
+	// sets a concrete zone; the service treats Unknown as "not gated" (only
+	// an explicit ZoneUSNexus triggers the I1 refusal) so the gate can
+	// never fire on a caller-controllable default.
+	ZoneUnknown Zone = iota
+	// ZoneSovereign is sovereign soil (homelab / Tailscale CLI callers).
+	ZoneSovereign
+	// ZoneUSNexus is a non-sovereign US-jurisdiction surface (e.g.
+	// claude.ai). Confidential captures through it are refused (I1).
+	ZoneUSNexus
+)
+
+// String renders the zone for audit/refusal messages.
+func (z Zone) String() string {
+	switch z {
+	case ZoneSovereign:
+		return "sovereign-soil"
+	case ZoneUSNexus:
+		return "us-nexus"
+	default:
+		return "unknown"
+	}
+}
+
 // CaptureContext is the per-session metadata accompanying a capture.
 //
 // Classification is the caller-declared sensitivity (model C, spec §4.1):
 // the server independently derives the target's classification and gates
-// on the stricter of the two. Principal is server-derived from the
-// authenticated identity (#53 populates it); it is never caller-asserted.
-// Harness is descriptive telemetry only — never a gate input.
+// on the stricter of the two. Principal and Origin are server-derived from
+// the authenticated identity (the REST adapter populates them); they are
+// never caller-asserted. Harness is descriptive telemetry only — never a
+// gate input.
 type CaptureContext struct {
 	Harness        string
 	SessionRef     string
@@ -29,6 +60,7 @@ type CaptureContext struct {
 	Actor          string
 	Classification string // caller-declared level token ("" = unspecified)
 	Principal      string // server-derived (auth); audit identity
+	Origin         Zone   // server-derived trust zone; the I1 gate input
 }
 
 // Insight is one piece of session knowledge bound for the brain. A
diff --git a/ingestion/internal/capture/service.go b/ingestion/internal/capture/service.go
index af893ce..98a83c9 100644
--- a/ingestion/internal/capture/service.go
+++ b/ingestion/internal/capture/service.go
@@ -34,6 +34,33 @@ func NewService(b BrainStore, tr IssueTracker, sw SummaryWriter, p Classificatio
 
 var validActions = map[string]bool{"create": true, "close": true, "comment": true}
 
+// ErrSovereigntyRefused is returned when the I1 gate refuses a capture
+// (confidential effective classification through a us-nexus origin). The
+// REST adapter maps it to HTTP 403. Callers test with errors.Is.
+var ErrSovereigntyRefused = fmt.Errorf("capture refused by I1 sovereignty gate")
+
+// assertedZoneMismatch returns a security-event string when the caller's
+// harness label asserts a trust zone that contradicts the server-derived
+// origin. A harness label that names no zone (the normal case, e.g.
+// "claude-code") returns "". The label is never used as a gate input —
+// this only flags the discrepancy for the audit trail.
+func assertedZoneMismatch(harness string, derived Zone) string {
+	var asserted Zone
+	switch strings.ToLower(strings.TrimSpace(harness)) {
+	case "sovereign-soil", "sovereign":
+		asserted = ZoneSovereign
+	case "us-nexus", "usnexus":
+		asserted = ZoneUSNexus
+	default:
+		return "" // no zone claim
+	}
+	if asserted != derived {
+		return fmt.Sprintf("asserted-vs-derived origin mismatch: harness asserted %s, principal resolves to %s",
+			asserted, derived)
+	}
+	return ""
+}
+
 // Capture runs the use-case: validate (fail-closed), resolve effective
 // classification (stricter of declared vs target-derived), then persist
 // insights → tickets → summary best-effort, emit an audit record, and
@@ -57,6 +84,32 @@ func (s *Service) Capture(ctx context.Context, in CaptureInput) (CaptureReceipt,
 
 	effective, securityEvents := s.resolveClassification(declared, in)
 
+	// Server-derived origin governs the I1 gate; a caller-asserted harness
+	// label that names a different zone is descriptive-only and logged as a
+	// security event (spec §4.2: a control keyed on attacker-suppliable
+	// input is not a control).
+	if ev := assertedZoneMismatch(in.Context.Harness, in.Context.Origin); ev != "" {
+		securityEvents = append(securityEvents, ev)
+	}
+
+	// I1 sovereignty gate: a confidential capture through a us-nexus origin
+	// is refused before ANY write. The refusal itself is audited (best
+	// effort) — refusals must be reconstructable too.
+	if effective == classification.Confidential && in.Context.Origin == ZoneUSNexus {
+		_ = s.audit.Record(ctx, AuditEntry{
+			Timestamp:               s.now().UTC(),
+			Principal:               in.Context.Principal,
+			Actor:                   in.Context.Actor,
+			Harness:                 in.Context.Harness,
+			SessionRef:              in.Context.SessionRef,
+			EffectiveClassification: effective.String(),
+			Items:                   nil, // refused before any write
+			SecurityEvents:          append(securityEvents, "I1 refusal: confidential capture via us-nexus origin"),
+		})
+		return CaptureReceipt{}, fmt.Errorf("%w: effective classification confidential through %s origin",
+			ErrSovereigntyRefused, in.Context.Origin)
+	}
+
 	receipt := CaptureReceipt{
 		Errors:                  []ItemError{},
 		EffectiveClassification: effective.String(),
diff --git a/ingestion/internal/capture/service_test.go b/ingestion/internal/capture/service_test.go
index b57df0a..2201513 100644
--- a/ingestion/internal/capture/service_test.go
+++ b/ingestion/internal/capture/service_test.go
@@ -329,3 +329,82 @@ func TestCaptureSummaryPathAndFidelity(t *testing.T) {
 	assert.Contains(t, sw.paths[0], "session-wrap")
 	assert.Contains(t, sw.content[0], "fidelity: transcript-parse", "fidelity stamped in frontmatter")
 }
+
+// --- I1 sovereignty gate (#53) ---
+
+func TestCaptureRefusesConfidentialViaUSNexus(t *testing.T) {
+	b := &fakeBrain{}
+	tr := &fakeTracker{}
+	au := &fakeAudit{}
+	pol := fakePolicy{tags: map[string]classification.Level{"client-seb": classification.Confidential}}
+	svc := newSvc(b, tr, nil, pol, au)
+
+	ctx := baseCtx()
+	ctx.Classification = "confidential"
+	ctx.Origin = ZoneUSNexus
+	_, err := svc.Capture(context.Background(), CaptureInput{
+		Context:  ctx,
+		Insights: []Insight{{Text: "x", Wing: "client-seb", Hall: "facts"}},
+	})
+	require.Error(t, err)
+	assert.ErrorIs(t, err, ErrSovereigntyRefused)
+	// Refused before any write.
+	assert.Empty(t, b.writes)
+	assert.Empty(t, tr.created)
+	// Refusal is audited.
+	require.Len(t, au.entries, 1)
+	assert.Empty(t, au.entries[0].Items, "no items landed on refusal")
+}
+
+func TestCaptureAllowsConfidentialViaSovereign(t *testing.T) {
+	b := &fakeBrain{}
+	pol := fakePolicy{tags: map[string]classification.Level{"client-seb": classification.Confidential}}
+	svc := newSvc(b, &fakeTracker{}, nil, pol, &fakeAudit{})
+
+	ctx := baseCtx()
+	ctx.Classification = "confidential"
+	ctx.Origin = ZoneSovereign
+	rec, err := svc.Capture(context.Background(), CaptureInput{
+		Context:  ctx,
+		Insights: []Insight{{Text: "x", Wing: "client-seb", Hall: "facts"}},
+	})
+	require.NoError(t, err)
+	assert.True(t, rec.Insights[0].OK)
+	assert.Len(t, b.writes, 1)
+}
+
+func TestCaptureAssertedLabelIgnoredAndLogged(t *testing.T) {
+	// Caller asserts harness "sovereign-soil" but principal resolves to
+	// us-nexus; confidential ⇒ refused, and the discrepancy is a security event.
+	au := &fakeAudit{}
+	pol := fakePolicy{tags: map[string]classification.Level{"client-seb": classification.Confidential}}
+	svc := newSvc(&fakeBrain{}, &fakeTracker{}, nil, pol, au)
+
+	ctx := baseCtx()
+	ctx.Harness = "sovereign-soil" // asserted
+	ctx.Origin = ZoneUSNexus       // server-derived
+	ctx.Classification = "confidential"
+	_, err := svc.Capture(context.Background(), CaptureInput{
+		Context:  ctx,
+		Insights: []Insight{{Text: "x", Wing: "client-seb", Hall: "facts"}},
+	})
+	require.ErrorIs(t, err, ErrSovereigntyRefused)
+	require.Len(t, au.entries, 1)
+	joined := strings.Join(au.entries[0].SecurityEvents, " | ")
+	assert.Contains(t, joined, "asserted-vs-derived origin mismatch")
+	assert.Contains(t, joined, "I1 refusal")
+}
+
+func TestCaptureInternalViaUSNexusAllowed(t *testing.T) {
+	// us-nexus origin is fine for non-confidential data.
+	b := &fakeBrain{}
+	svc := newSvc(b, &fakeTracker{}, nil, fakePolicy{}, &fakeAudit{})
+	ctx := baseCtx()
+	ctx.Origin = ZoneUSNexus // internal classification, so gate doesn't fire
+	rec, err := svc.Capture(context.Background(), CaptureInput{
+		Context:  ctx,
+		Insights: []Insight{{Text: "x", Wing: "hyperguild", Hall: "facts"}},
+	})
+	require.NoError(t, err)
+	assert.True(t, rec.Insights[0].OK)
+}
diff --git a/ingestion/internal/capturehttp/handler.go b/ingestion/internal/capturehttp/handler.go
new file mode 100644
index 0000000..8bc73f0
--- /dev/null
+++ b/ingestion/internal/capturehttp/handler.go
@@ -0,0 +1,211 @@
+// Package capturehttp is the REST adapter for the capture use-case: the
+// POST /capture door (#53). It is deliberately thin — authenticate, derive
+// the trust-zone origin from the authenticated principal, decode the
+// request, call capture.Service, map the receipt to an HTTP status. No
+// business logic lives here; the I1 gate, validation, and orchestration
+// are all in the use-case.
+package capturehttp
+
+import (
+	"context"
+	"crypto/subtle"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"strings"
+
+	"github.com/mathiasbq/hyperguild/ingestion/internal/capture"
+)
+
+// Validator validates a Bearer JWT and returns its subject. The chassis
+// *auth.JWTValidator satisfies it (including its nil-receiver "disabled"
+// behaviour), and tests can substitute a fake without a live JWKS.
+type Validator interface {
+	Validate(ctx context.Context, rawToken string) (string, error)
+}
+
+// Handler serves POST /capture.
+type Handler struct {
+	svc             *capture.Service
+	validator       Validator // nil ⇒ JWT auth disabled
+	staticToken     string    // "" ⇒ static auth disabled
+	staticPrincipal string    // principal name attributed to static-token callers
+	resolver        OriginResolver
+}
+
+// New constructs a capture HTTP handler. staticToken callers are
+// attributed to staticPrincipal (a sovereign homelab identity); JWT
+// callers are attributed to their token subject.
+func New(svc *capture.Service, validator Validator, staticToken, staticPrincipal string, resolver OriginResolver) *Handler {
+	if staticPrincipal == "" {
+		staticPrincipal = "local-cli"
+	}
+	return &Handler{
+		svc:             svc,
+		validator:       validator,
+		staticToken:     staticToken,
+		staticPrincipal: staticPrincipal,
+		resolver:        resolver,
+	}
+}
+
+// wire types — the POST /capture request body.
+type request struct {
+	Context  contextBody   `json:"context"`
+	Insights []insightBody `json:"insights"`
+	Tickets  []ticketBody  `json:"tickets"`
+	Summary  *summaryBody  `json:"summary,omitempty"`
+	DryRun   bool          `json:"dry_run"`
+}
+
+type contextBody struct {
+	Harness        string `json:"harness"`
+	SessionRef     string `json:"session_ref"`
+	Fidelity       string `json:"fidelity"`
+	Actor          string `json:"actor"`
+	Classification string `json:"classification"`
+}
+
+type insightBody struct {
+	Text          string `json:"text"`
+	Wing          string `json:"wing"`
+	Hall          string `json:"hall"`
+	SupersedeSlug string `json:"supersede_slug,omitempty"`
+}
+
+type ticketBody struct {
+	Repo   string `json:"repo"`
+	Action string `json:"action"`
+	Number int    `json:"number,omitempty"`
+	Title  string `json:"title,omitempty"`
+	Body   string `json:"body,omitempty"`
+}
+
+type summaryBody struct {
+	Title        string   `json:"title"`
+	Body         string   `json:"body"`
+	ReposTouched []string `json:"repos_touched,omitempty"`
+}
+
+// ServeHTTP authenticates, derives origin, runs the use-case, and maps the
+// result to an HTTP status.
+func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	principal, viaStatic, ok := h.authenticate(r)
+	if !ok {
+		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		return
+	}
+
+	var req request
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON"})
+		return
+	}
+
+	in := req.toInput()
+	// Principal and origin are server-derived — overwrite anything the
+	// caller may have tried to put in the body.
+	in.Context.Principal = principal
+	in.Context.Origin = h.resolver.Resolve(principal, viaStatic)
+
+	rec, err := h.svc.Capture(r.Context(), in)
+	switch {
+	case errors.Is(err, capture.ErrSovereigntyRefused):
+		writeJSON(w, http.StatusForbidden, map[string]string{"error": err.Error()})
+		return
+	case err != nil:
+		// Pre-write validation failure (fail-closed).
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
+		return
+	}
+	writeJSON(w, statusFor(rec), rec)
+}
+
+// authenticate mirrors the chassis Bearer precedence (static wins, then
+// JWT) but returns the resolved principal and whether the static path was
+// taken — the chassis middleware hides both, and capture needs them to
+// derive the origin.
+func (h *Handler) authenticate(r *http.Request) (principal string, viaStatic, ok bool) {
+	raw, found := strings.CutPrefix(r.Header.Get("Authorization"), "Bearer ")
+	if !found || raw == "" {
+		return "", false, false
+	}
+	if h.staticToken != "" && subtle.ConstantTimeCompare([]byte(raw), []byte(h.staticToken)) == 1 {
+		return h.staticPrincipal, true, true
+	}
+	if h.validator != nil {
+		if sub, err := h.validator.Validate(r.Context(), raw); err == nil && sub != "" {
+			return sub, false, true
+		}
+	}
+	return "", false, false
+}
+
+func (b request) toInput() capture.CaptureInput {
+	in := capture.CaptureInput{
+		Context: capture.CaptureContext{
+			Harness:        b.Context.Harness,
+			SessionRef:     b.Context.SessionRef,
+			Fidelity:       b.Context.Fidelity,
+			Actor:          b.Context.Actor,
+			Classification: b.Context.Classification,
+		},
+		DryRun: b.DryRun,
+	}
+	for _, i := range b.Insights {
+		in.Insights = append(in.Insights, capture.Insight{
+			Text: i.Text, Wing: i.Wing, Hall: i.Hall, SupersedeSlug: i.SupersedeSlug,
+		})
+	}
+	for _, t := range b.Tickets {
+		in.Tickets = append(in.Tickets, capture.Ticket{
+			Repo: t.Repo, Action: t.Action, Number: t.Number, Title: t.Title, Body: t.Body,
+		})
+	}
+	if b.Summary != nil {
+		in.Summary = &capture.Summary{
+			Title: b.Summary.Title, Body: b.Summary.Body, ReposTouched: b.Summary.ReposTouched,
+		}
+	}
+	return in
+}
+
+// statusFor maps a receipt to an HTTP status: 200 all-ok (or dry-run),
+// 207 partial, 502 everything-failed.
+func statusFor(rec capture.CaptureReceipt) int {
+	if rec.DryRun {
+		return http.StatusOK
+	}
+	var ok, fail int
+	for _, i := range rec.Insights {
+		count(&ok, &fail, i.OK)
+	}
+	for _, t := range rec.Tickets {
+		count(&ok, &fail, t.OK)
+	}
+	if rec.Summary != nil {
+		count(&ok, &fail, rec.Summary.OK)
+	}
+	switch {
+	case fail == 0:
+		return http.StatusOK
+	case ok == 0:
+		return http.StatusBadGateway // every persistence attempt failed
+	default:
+		return http.StatusMultiStatus // 207: partial success
+	}
+}
+
+func count(ok, fail *int, isOK bool) {
+	if isOK {
+		*ok++
+	} else {
+		*fail++
+	}
+}
+
+func writeJSON(w http.ResponseWriter, status int, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(v)
+}
diff --git a/ingestion/internal/capturehttp/handler_test.go b/ingestion/internal/capturehttp/handler_test.go
new file mode 100644
index 0000000..a2247cc
--- /dev/null
+++ b/ingestion/internal/capturehttp/handler_test.go
@@ -0,0 +1,178 @@
+package capturehttp_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/mathiasbq/hyperguild/ingestion/internal/audit"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/brainstore"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/capture"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/capturehttp"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/classification"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+const staticTok = "static-secret"
+
+// fakeValidator stands in for the chassis JWT validator.
+type fakeValidator struct {
+	subject string
+	err     error
+}
+
+func (f fakeValidator) Validate(context.Context, string) (string, error) {
+	return f.subject, f.err
+}
+
+type fakeTracker struct{ failCreate bool }
+
+func (f fakeTracker) CreateIssue(context.Context, string, string, string) (capture.IssueRef, error) {
+	if f.failCreate {
+		return capture.IssueRef{}, errors.New("gitea down")
+	}
+	return capture.IssueRef{Repo: "hyperguild", Number: 1, URL: "https://git/1"}, nil
+}
+func (fakeTracker) CloseIssue(context.Context, string, int, string) (capture.IssueRef, error) {
+	return capture.IssueRef{}, nil
+}
+func (fakeTracker) CommentIssue(context.Context, string, int, string) (capture.IssueRef, error) {
+	return capture.IssueRef{}, nil
+}
+
+func newHandler(t *testing.T, v capturehttp.Validator, tr capture.IssueTracker, sovereign []string) *capturehttp.Handler {
+	t.Helper()
+	cfg, err := classification.Load(t.TempDir())
+	require.NoError(t, err)
+	svc := capture.NewService(brainstore.New(t.TempDir()), tr, nil, cfg, audit.NewSlogSink(nil))
+	return capturehttp.New(svc, v, staticTok, "local-cli", capturehttp.NewOriginResolver(sovereign))
+}
+
+func do(t *testing.T, h *capturehttp.Handler, authz string, body any) *httptest.ResponseRecorder {
+	t.Helper()
+	b, _ := json.Marshal(body)
+	req := httptest.NewRequest(http.MethodPost, "/capture", bytes.NewReader(b))
+	if authz != "" {
+		req.Header.Set("Authorization", authz)
+	}
+	rr := httptest.NewRecorder()
+	h.ServeHTTP(rr, req)
+	return rr
+}
+
+func internalReq() map[string]any {
+	return map[string]any{
+		"context":  map[string]any{"harness": "claude-code", "actor": "mathias", "classification": "internal"},
+		"insights": []map[string]any{{"text": "a fact", "wing": "hyperguild", "hall": "facts"}},
+	}
+}
+
+func TestUnauthorizedWithoutToken(t *testing.T) {
+	h := newHandler(t, fakeValidator{err: errors.New("no")}, fakeTracker{}, nil)
+	rr := do(t, h, "", internalReq())
+	assert.Equal(t, http.StatusUnauthorized, rr.Code)
+}
+
+func TestUnauthorizedBadToken(t *testing.T) {
+	h := newHandler(t, fakeValidator{err: errors.New("bad jwt")}, fakeTracker{}, nil)
+	rr := do(t, h, "Bearer wrong", internalReq())
+	assert.Equal(t, http.StatusUnauthorized, rr.Code)
+}
+
+func TestHappyPathStaticToken(t *testing.T) {
+	h := newHandler(t, nil, fakeTracker{}, nil)
+	rr := do(t, h, "Bearer "+staticTok, map[string]any{
+		"context":  map[string]any{"harness": "claude-code", "actor": "mathias", "classification": "internal"},
+		"insights": []map[string]any{{"text": "a fact", "wing": "hyperguild", "hall": "facts"}},
+		"tickets":  []map[string]any{{"repo": "hyperguild", "action": "create", "title": "t"}},
+	})
+	require.Equal(t, http.StatusOK, rr.Code)
+	var rec capture.CaptureReceipt
+	require.NoError(t, json.Unmarshal(rr.Body.Bytes(), &rec))
+	assert.True(t, rec.Insights[0].OK)
+	assert.True(t, rec.Tickets[0].OK)
+	assert.Empty(t, rec.Errors)
+}
+
+func TestConfidentialViaUSNexusRefused(t *testing.T) {
+	// JWT principal not in the sovereign allowlist ⇒ us-nexus; confidential ⇒ 403.
+	h := newHandler(t, fakeValidator{subject: "claudeai-oauth-client"}, fakeTracker{}, nil)
+	rr := do(t, h, "Bearer jwt-token", map[string]any{
+		"context":  map[string]any{"harness": "claudeai-chat", "actor": "mathias", "classification": "confidential"},
+		"insights": []map[string]any{{"text": "secret", "wing": "client-seb", "hall": "facts"}},
+	})
+	assert.Equal(t, http.StatusForbidden, rr.Code)
+	assert.Contains(t, rr.Body.String(), "sovereignty")
+}
+
+func TestConfidentialViaSovereignJWTAllowed(t *testing.T) {
+	// Same confidential payload, but the principal is allowlisted sovereign ⇒ allowed.
+	h := newHandler(t, fakeValidator{subject: "koala-cli"}, fakeTracker{}, []string{"koala-cli"})
+	rr := do(t, h, "Bearer jwt-token", map[string]any{
+		"context":  map[string]any{"harness": "claude-code", "actor": "mathias", "classification": "confidential"},
+		"insights": []map[string]any{{"text": "secret", "wing": "client-seb", "hall": "facts"}},
+	})
+	require.Equal(t, http.StatusOK, rr.Code)
+}
+
+func TestStaticTokenIsSovereignSoConfidentialAllowed(t *testing.T) {
+	h := newHandler(t, nil, fakeTracker{}, nil)
+	rr := do(t, h, "Bearer "+staticTok, map[string]any{
+		"context":  map[string]any{"harness": "claude-code", "actor": "mathias", "classification": "confidential"},
+		"insights": []map[string]any{{"text": "secret", "wing": "client-seb", "hall": "facts"}},
+	})
+	assert.Equal(t, http.StatusOK, rr.Code)
+}
+
+func TestValidationRejectedBeforeWrite(t *testing.T) {
+	h := newHandler(t, nil, fakeTracker{}, nil)
+	rr := do(t, h, "Bearer "+staticTok, map[string]any{
+		"context":  map[string]any{"actor": "mathias", "classification": "internal"},
+		"insights": []map[string]any{{"text": "x", "wing": "hyperguild", "hall": "not-a-hall"}},
+	})
+	assert.Equal(t, http.StatusBadRequest, rr.Code)
+}
+
+func TestPartialFailureIs207(t *testing.T) {
+	h := newHandler(t, nil, fakeTracker{failCreate: true}, nil)
+	rr := do(t, h, "Bearer "+staticTok, map[string]any{
+		"context":  map[string]any{"harness": "claude-code", "actor": "mathias", "classification": "internal"},
+		"insights": []map[string]any{{"text": "ok insight", "wing": "hyperguild", "hall": "facts"}},
+		"tickets":  []map[string]any{{"repo": "hyperguild", "action": "create", "title": "fails"}},
+	})
+	assert.Equal(t, http.StatusMultiStatus, rr.Code)
+	var rec capture.CaptureReceipt
+	require.NoError(t, json.Unmarshal(rr.Body.Bytes(), &rec))
+	assert.True(t, rec.Insights[0].OK)
+	assert.False(t, rec.Tickets[0].OK)
+	assert.Len(t, rec.Errors, 1)
+}
+
+func TestDryRunWritesNothing(t *testing.T) {
+	h := newHandler(t, nil, fakeTracker{}, nil)
+	rr := do(t, h, "Bearer "+staticTok, map[string]any{
+		"context":  map[string]any{"harness": "claude-code", "actor": "mathias", "classification": "internal"},
+		"insights": []map[string]any{{"text": "a", "wing": "hyperguild", "hall": "facts"}},
+		"dry_run":  true,
+	})
+	require.Equal(t, http.StatusOK, rr.Code)
+	var rec capture.CaptureReceipt
+	require.NoError(t, json.Unmarshal(rr.Body.Bytes(), &rec))
+	assert.True(t, rec.DryRun)
+}
+
+func TestCallerCannotForgeOrigin(t *testing.T) {
+	// Even if the body tried to assert a sovereign harness, a us-nexus JWT
+	// principal + confidential ⇒ refused. (Origin is server-derived.)
+	h := newHandler(t, fakeValidator{subject: "claudeai-oauth-client"}, fakeTracker{}, nil)
+	rr := do(t, h, "Bearer jwt", map[string]any{
+		"context":  map[string]any{"harness": "sovereign-soil", "actor": "mathias", "classification": "confidential"},
+		"insights": []map[string]any{{"text": "secret", "wing": "client-seb", "hall": "facts"}},
+	})
+	assert.Equal(t, http.StatusForbidden, rr.Code)
+}
diff --git a/ingestion/internal/capturehttp/origin.go b/ingestion/internal/capturehttp/origin.go
new file mode 100644
index 0000000..b449371
--- /dev/null
+++ b/ingestion/internal/capturehttp/origin.go
@@ -0,0 +1,42 @@
+package capturehttp
+
+import "github.com/mathiasbq/hyperguild/ingestion/internal/capture"
+
+// OriginResolver maps an authenticated principal to its trust zone
+// (spec §4.2). The mapping is server-side and never reads caller input.
+//
+// Rules:
+//   - The static-token path is a homelab CLI caller on sovereign soil →
+//     ZoneSovereign.
+//   - A JWT principal in the sovereign allowlist → ZoneSovereign.
+//   - Any other JWT principal (e.g. claude.ai's OAuth identity, or any
+//     unrecognised subject) → ZoneUSNexus.
+//
+// The default is the strict one: an unknown principal is treated as
+// us-nexus so the I1 gate fails safe (refuses confidential), exactly as
+// an untagged classification target fails safe to confidential (#50).
+type OriginResolver struct {
+	sovereign map[string]bool
+}
+
+// NewOriginResolver builds a resolver whose JWT sovereign principals are
+// the given subjects. The static-token caller is always sovereign and
+// need not be listed.
+func NewOriginResolver(sovereignPrincipals []string) OriginResolver {
+	m := make(map[string]bool, len(sovereignPrincipals))
+	for _, p := range sovereignPrincipals {
+		if p != "" {
+			m[p] = true
+		}
+	}
+	return OriginResolver{sovereign: m}
+}
+
+// Resolve returns the trust zone for a principal. viaStatic is true when
+// the static-token auth path was taken.
+func (r OriginResolver) Resolve(principal string, viaStatic bool) capture.Zone {
+	if viaStatic || r.sovereign[principal] {
+		return capture.ZoneSovereign
+	}
+	return capture.ZoneUSNexus
+}
diff --git a/ingestion/internal/mcp/server.go b/ingestion/internal/mcp/server.go
index a88a21b..84d94d5 100644
--- a/ingestion/internal/mcp/server.go
+++ b/ingestion/internal/mcp/server.go
@@ -116,6 +116,13 @@ func (s *Server) IssueTracker() capture.IssueTracker {
 	return s.tracker
 }
 
+// BrainStore returns the shared brain store (graph-wired once WithGraph
+// has run), so the capture use-case writes through the exact same
+// implementation as the MCP handlers.
+func (s *Server) BrainStore() *brainstore.Store {
+	return s.store
+}
+
 func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// MCP streamable HTTP: GET establishes the SSE stream for server-to-client events.
 	if r.Method == http.MethodGet {