Mid-to-large engineering organizations embedding LLMs into products face rising and unpredictable costs from per-call and per-token billing, as well as invisible failures like prompt regression and model drift that traditional APM and cost tools were not built to detect. Across an addressable market of roughly 200,000 such orgs (a $12.0B opportunity at about $60K ACV), engineering leaders and FinOps need attribution to features, users, and dollar impact so they can stop paying for silent ROI erosion. You could build a developer-facing observability layer that captures call-level LLM telemetry, attributes tokens/latency to features and users, detects statistical drift and prompt regressions, and translates anomalies into dollar impact, remediation playbooks, and forecasts. Practically this requires lightweight SDKs/sidecars, ML anomaly detection tuned to LLM call semantics, out-of-the-box integrations with tracing and metrics stacks, and UX that surfaces quick wins for cost reduction and reliability improvements. Timing is favorable because LLM-first development, usage-based billing, and convergence of observability standards mean teams are actively seeking this capability now rather than waiting. Competition is medium—traditional APM vendors and new startups will move in—so defensibility depends on domain expertise in LLM semantics, low-friction instrumentation, strong provider partnerships, and the ability to prove clear dollar savings quickly while managing challenges around API heterogeneity and data privacy.