CHANGELOG
Product Updates
New features, infrastructure upgrades, and SDK releases.
Feature
Introduced Anycast Network Routing
Engineering Summary
This release migrates Meridian’s global ingress layer from unicast BGP routing to a full Anycast architecture spanning 23 points of presence across North America, Europe, and Asia-Pacific. Under the previous model, DNS-based geo-steering introduced up to 140ms of additional round-trip latency for clients whose resolver cache had drifted from the optimal origin. With Anycast, all Meridian API traffic is automatically absorbed by the topologically closest PoP without relying on DNS TTL propagation — eliminating resolver drift as a latency variable entirely.
Performance Impact
Internal benchmarks conducted across 14 AWS, GCP, and Azure regions show a median latency reduction of 34ms on the /v1/inference endpoint and a P99 improvement of 61ms on cold-path requests that previously traversed inter-continental backbone segments. Anycast also improves resilience: a PoP failure now causes BGP to withdraw the affected prefix within 8 seconds, rerouting traffic to the next closest node with no client-side DNS flush required. No SDK changes or configuration updates are required; all existing API keys and endpoint URLs continue to function without modification.
Feature
Introduced Anycast Network Routing
Engineering Summary
This release migrates Meridian’s global ingress layer from unicast BGP routing to a full Anycast architecture spanning 23 points of presence across North America, Europe, and Asia-Pacific. Under the previous model, DNS-based geo-steering introduced up to 140ms of additional round-trip latency for clients whose resolver cache had drifted from the optimal origin. With Anycast, all Meridian API traffic is automatically absorbed by the topologically closest PoP without relying on DNS TTL propagation — eliminating resolver drift as a latency variable entirely.
Performance Impact
Internal benchmarks conducted across 14 AWS, GCP, and Azure regions show a median latency reduction of 34ms on the /v1/inference endpoint and a P99 improvement of 61ms on cold-path requests that previously traversed inter-continental backbone segments. Anycast also improves resilience: a PoP failure now causes BGP to withdraw the affected prefix within 8 seconds, rerouting traffic to the next closest node with no client-side DNS flush required. No SDK changes or configuration updates are required; all existing API keys and endpoint URLs continue to function without modification.
Security
Enforced TLS 1.3 Across All Data Planes
Engineering Summary
Effective this release, Meridian has deprecated TLS 1.2 on all API endpoints, webhook delivery agents, and OTLP export pipelines. Connections negotiating TLS 1.2 will receive a SSL_PROTOCOL_ERROR and be immediately terminated at the ingress layer. This change enforces TLS 1.3 as the sole accepted protocol, which eliminates the RSA key exchange vulnerability surface, mandates forward secrecy on every session via ephemeral Diffie-Hellman, and removes support for cipher suites flagged in NIST SP 800-52 Rev. 2 as legacy-inadequate. All Meridian SDK versions 1.4.0 and above have shipped with TLS 1.3-only configuration since March 2026.
Migration & Compliance Impact
Tenants running SDK versions below 1.4.0 or operating HTTP clients with system-level OpenSSL builds older than 1.1.1 must upgrade prior to this change taking effect in their production environment. The Meridian compliance dashboard now emits a TLS_LEGACY_DETECTED warning event for any connection that attempted TLS 1.2 negotiation in the trailing 30-day window, giving security teams full visibility into affected clients before enforcement. This change advances Meridian’s SOC 2 Type II and ISO 27001 posture and satisfies controls mandated by several enterprise customer security annexes effective Q3 2026.
Security
Enforced TLS 1.3 Across All Data Planes
Engineering Summary
Effective this release, Meridian has deprecated TLS 1.2 on all API endpoints, webhook delivery agents, and OTLP export pipelines. Connections negotiating TLS 1.2 will receive a SSL_PROTOCOL_ERROR and be immediately terminated at the ingress layer. This change enforces TLS 1.3 as the sole accepted protocol, which eliminates the RSA key exchange vulnerability surface, mandates forward secrecy on every session via ephemeral Diffie-Hellman, and removes support for cipher suites flagged in NIST SP 800-52 Rev. 2 as legacy-inadequate. All Meridian SDK versions 1.4.0 and above have shipped with TLS 1.3-only configuration since March 2026.
Migration & Compliance Impact
Tenants running SDK versions below 1.4.0 or operating HTTP clients with system-level OpenSSL builds older than 1.1.1 must upgrade prior to this change taking effect in their production environment. The Meridian compliance dashboard now emits a TLS_LEGACY_DETECTED warning event for any connection that attempted TLS 1.2 negotiation in the trailing 30-day window, giving security teams full visibility into affected clients before enforcement. This change advances Meridian’s SOC 2 Type II and ISO 27001 posture and satisfies controls mandated by several enterprise customer security annexes effective Q3 2026.
Deprecation
Deprecated v1 Pipeline Execution API
Engineering Summary
The v1 Pipeline Execution API (/v1/pipelines/run, /v1/pipelines/status) is now formally deprecated with a hard sunset date of September 1, 2026. The v1 surface lacks support for streaming step outputs, conditional branching, and the typed artifact system introduced in the v2 pipeline engine. All net-new pipeline definitions created after May 5, 2026 default to the v2 execution runtime at /v2/pipelines/execute. Existing v1 pipeline definitions remain readable and executable until sunset, but will not receive feature updates or non-critical bug fixes.
Migration Path
The v2 Pipeline API introduces a declarative step graph schema that replaces the v1 sequential array model with a directed acyclic graph supporting parallel branch execution and typed inter-step contracts. Meridian has published an automated migration tool — meridian pipelines migrate --from v1 --dry-run — that converts v1 YAML definitions to valid v2 schemas with a compatibility report. Teams operating more than 10 active v1 pipelines should contact their enterprise support channel to schedule a migration review session. Telemetry for v1 API calls is surfaced in the dashboard under the Deprecation Tracker panel introduced in this release.
Deprecation
Deprecated v1 Pipeline Execution API
Engineering Summary
The v1 Pipeline Execution API (/v1/pipelines/run, /v1/pipelines/status) is now formally deprecated with a hard sunset date of September 1, 2026. The v1 surface lacks support for streaming step outputs, conditional branching, and the typed artifact system introduced in the v2 pipeline engine. All net-new pipeline definitions created after May 5, 2026 default to the v2 execution runtime at /v2/pipelines/execute. Existing v1 pipeline definitions remain readable and executable until sunset, but will not receive feature updates or non-critical bug fixes.
Migration Path
The v2 Pipeline API introduces a declarative step graph schema that replaces the v1 sequential array model with a directed acyclic graph supporting parallel branch execution and typed inter-step contracts. Meridian has published an automated migration tool — meridian pipelines migrate --from v1 --dry-run — that converts v1 YAML definitions to valid v2 schemas with a compatibility report. Teams operating more than 10 active v1 pipelines should contact their enterprise support channel to schedule a migration review session. Telemetry for v1 API calls is surfaced in the dashboard under the Deprecation Tracker panel introduced in this release.
Feature
Launched Structured Output Mode for All Models
Engineering Summary
Structured Output Mode is now generally available across all model tiers in the Meridian inference surface. When a JSON Schema is passed in the output_schema request parameter, Meridian’s constrained decoding layer modifies the per-token probability distribution at inference time to guarantee that the model’s output is a valid instance of the supplied schema — without post-hoc parsing, retries, or prompt-engineering workarounds. This is implemented via a finite-state-machine token mask derived at request time from the schema’s compiled grammar, adding a median overhead of 1.8ms to first-token latency.
Developer Impact
Structured outputs eliminate an entire class of production failures caused by LLM format non-compliance — a leading source of pipeline exceptions in agentic applications. In closed beta, teams using structured output mode reported a 97.3% reduction in JSON parsing exceptions and a measurable decrease in retry-induced token cost. Schema validation errors — for instance, submitting an unsupported $ref recursion — now return a typed SCHEMA_COMPILATION_ERROR with a precise pointer to the offending schema node, replacing the generic 400 Bad Request previously returned. Full JSON Schema Draft 7 and Draft 2020-12 are supported; XML and YAML output schemas are on the roadmap for v2.2.
Feature
Launched Structured Output Mode for All Models
Engineering Summary
Structured Output Mode is now generally available across all model tiers in the Meridian inference surface. When a JSON Schema is passed in the output_schema request parameter, Meridian’s constrained decoding layer modifies the per-token probability distribution at inference time to guarantee that the model’s output is a valid instance of the supplied schema — without post-hoc parsing, retries, or prompt-engineering workarounds. This is implemented via a finite-state-machine token mask derived at request time from the schema’s compiled grammar, adding a median overhead of 1.8ms to first-token latency.
Developer Impact
Structured outputs eliminate an entire class of production failures caused by LLM format non-compliance — a leading source of pipeline exceptions in agentic applications. In closed beta, teams using structured output mode reported a 97.3% reduction in JSON parsing exceptions and a measurable decrease in retry-induced token cost. Schema validation errors — for instance, submitting an unsupported $ref recursion — now return a typed SCHEMA_COMPILATION_ERROR with a precise pointer to the offending schema node, replacing the generic 400 Bad Request previously returned. Full JSON Schema Draft 7 and Draft 2020-12 are supported; XML and YAML output schemas are on the roadmap for v2.2.
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