Enterprises rarely fail because their language model is incapable; they fail because the prompt pathway is opaque. We introduce prompt–centric observability (PCO), an operational discipline that treats inputs, routing, retrieval, templating, safety overlays, generation, and validation as first–class, measurable surfaces. PCO emits low–cardinality signals (coverage, support, freshness, p95, spend), binds drafts to the exact evidence spans they used, and routes decisions through a governed gate (release, rewrite, redact, escalate). We present a compact architecture, a minimal telemetry hook, and actionable controls for entitlements, privacy, and auditability. The goal is not a new leaderboard but predictable behavior under change: when data, policies, or templates shift, the system responds within guardrails and every outcome is replayable.