Reconcile docs with reality; fix module graph, token compare, health

Acts on the 2026-07-30 senior review (REVIEW.md findings 1, 2, 4, 5, 7).

Docs (finding 1): CLAUDE.md and AGENTS.md both claimed Design B "has zero
clients - no worker binary exists". cmd/orchestra-worker/main.go is the
deployed worker, and the non-local-herdr guardrail has landed in
Coordinator.adapterFor. Both sections rewritten; AUDIT.md gains a matching
federation-status record. The Phase 5 retention / Phase 6 deletion decision
for Design A is preserved, not flattened.

clients/ un-ignored and tracked, including the .service unit and README:
deployed code belongs in version control. Design A is NOT deleted here.

progress.md (finding 2): the file was deleted after 636ed8a, yet CLAUDE.md
instructed every session to cross-check against it. References removed from
CLAUDE.md, AGENTS.md, internal/orchestrator/rotation_test.go (comment only)
and deploy/hooks/orchestra-codex-poll.sh; AUDIT.md now carries the log role.

web/go.mod (finding 4): a module stub ends the parent package graph at the
directory boundary, so go list ./... no longer yields
web/node_modules/flatted/golang/pkg/flatted. A build tag cannot work - the
package is in the package list before tags are evaluated. Local/CI-only
breakage: Dockerfile.api builds ./cmd/orchestra by explicit path and
.dockerignore already excluded node_modules.

orchestra-worker (finding 5): untracked (8.9MB, mode 100755, still on disk);
both binaries now gitignored.

Token compare (finding 7): cmd/orchestra/main.go:139,582 use
subtle.ConstantTimeCompare, matching the authz.go idiom. The token != ""
guard stays first, so an empty configured token still means auth-disabled
rather than auth-bypass. Three further plain != secret compares remain in
internal/federation/federation.go:343,346,368 - tracked, not fixed here.

Also included from the review pass: orchestrator.go records adapter-resolution
failures in SessionHealth.LastError instead of dropping them on a bare
continue, plus an Observed flag so lease-seeded health is not mistaken for a
live reading, with a covering test. GET /v1/tasks/<id>/health now returns a
record with last_error where it previously returned a bare 404.

REVIEW.md's own second pass claimed every checkable fact held up; four did
not. AUDIT.md never contained the false Design B claim (AGENTS.md was the
second copy), the guardrail is at orchestrator.go:312 not :309, the
progress.md site list missed the codex-poll hook, and only orchestra-worker
was tracked. Verified: go build, go vet, go test, and
go list ./... | grep node_modules all clean with every change applied
together. No live herdr or pane was touched; nothing was deployed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GEugbHVYfAXFpTqDYbByEB

cmd/orchestra/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"crypto/subtle"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -136,7 +137,7 @@ func (h harnessCompletion) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
 		return
 	}
-	if h.token != "" && r.Header.Get("Authorization") != "Bearer "+h.token {
+	if h.token != "" && subtle.ConstantTimeCompare([]byte(r.Header.Get("Authorization")), []byte("Bearer "+h.token)) != 1 {
 		http.Error(w, "unauthorized", http.StatusUnauthorized)
 		return
 	}
@@ -567,8 +568,9 @@ func main() {
 	})
 	// /v1/harness/turn is the unified turn-decision endpoint (AUDIT.md Phase
 	// 2 items 1-2): the Face-B stop hook posts here on every ordinary turn
-	// boundary (report marker absent — /v1/harness/complete covers task
-	// completion separately) and gets back exactly one of continue /
+	// boundary (task completion is not handled here — it goes through the
+	// authenticated worker completion endpoint, since the retired
+	// /v1/harness/complete had no fencing epoch) and gets back continue /
 	// prepare_handoff / rotate_now / refuse, per spec §5.3. This replaces
 	// what would otherwise be separate ad-hoc marker-file conventions per
 	// decision.
@@ -577,7 +579,7 @@ func main() {
 			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
 			return
 		}
-		if harnessToken != "" && r.Header.Get("Authorization") != "Bearer "+harnessToken {
+		if harnessToken != "" && subtle.ConstantTimeCompare([]byte(r.Header.Get("Authorization")), []byte("Bearer "+harnessToken)) != 1 {
 			http.Error(w, "unauthorized", http.StatusUnauthorized)
 			return
 		}