Service-level objective (SLO)-as-code tools make per-service reliability declarative, but users experience journeys: end-to-end executions whose availability and tail latency emerge from topology, routing, redundancy, timeouts/fallbacks, shared failure domains, and tail amplification. Journey objectives are therefore often maintained outside code and drift away from the effective runtime graph. We propose Emergence-as-Code (EmaC), a declarative contract that compiles journey-level SLI bounds and governance artifacts for declared SLOs from intent and evidence. An EmaC specification defines a typed journey expression, leaf bindings to atomic SLOs and telemetry, failure-domain assumptions, and guarded actions. Model Discovery proposes evidence-backed deltas for edges, branch probabilities, redundancy groups, and failure-domain hypotheses; each delta carries provenance and confidence. The compiler derives optimistic and pessimistic journey bounds and emits reviewable governance artifacts. An executable checkout replay shows that local SLOs can remain green while evidence-backed discovery changes the failure-domain model, collapses the pessimistic payment-race bound, and changes the rollout decision from pass to fail or review.