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Sequential Pipeline Orchestration

Intent

Coordinate multi-phase verification, assessment, and steering pipelines through an ordered sequential execution spine that propagates shared context and halts immediately on governance failure.

Context

In automated architecture steering and agentic evaluation workflows, tasks have strict dependencies where downstream operations depend directly on artifacts produced by preceding steps. Without deterministic sequencing, agent operations risk non-reproducible execution paths and state corruption.

Agentic Profile

Restricts autonomous agents to bounded, ordered pipeline stages, eliminating unconstrained loop cycles while standardizing context handoffs across phase boundaries.

Forces

Balances the necessity for deterministic phase ordering and fail-fast governance gating against the throughput constraints of linear execution.

Drivers

  • Need for predictable, reproducible stage ordering in CI/CD architecture validation
  • Requirement to terminate execution immediately on compliance failure to conserve compute and avoid corrupt state
  • Deterministic context accumulation across disparate analysis and generation steps

Constraints

  • Linear step progression prevents concurrent out-of-order state mutations
  • All steps must adhere to a standardized context propagation interface

Tradeoffs

  • Sequential stage execution incurs latency overhead relative to unconstrained asynchronous DAG evaluation
  • Rigid phase order limits spontaneous emergent problem-solving by autonomous agents

Solution

Encapsulate pipeline execution within a centralized coordinator (FlowRunner) that processes registered steps sequentially. The coordinator maintains an append-only execution context passed across stages, short-circuits on step failure or critical governance violation, and emits deterministic return codes and execution traces.

Operationalisation

Deploy as the primary execution engine across command-line interfaces and continuous integration workflows for continuous architecture analysis.

Workflow Implications

  • Every pipeline step must define explicit input requirements and output contracts registered in a step catalog
  • Execution runners must catch exceptions and convert governance violations into structured non-zero exit codes
  • Shared execution context must remain auditable and inspectable throughout runtime

Automation Opportunities

  • Automated step-level latency and token tracing via OpenTelemetry instrumentation
  • Automated generation of stage diagnostic summaries on abrupt pipeline halt

Implementation Signals

Identified in FlowRunner implementation in src/cas_runner/runner.py, step registration in src/cas_runner/steps/registry.py, and automated invocations in .github/workflows/cas-continuous-architecture.yml.

Evidence

Validated by active usage across the core runner runtime and verified alignment with automated delivery pipelines.

Signals

  • recurring_signals: Consolidated 9 overlapping sequential flow and runner proposals into a canonical pipeline architecture
  • verified_production_usage: FlowRunner orchestrates continuous architecture loops and governance validation gates in CI

Supporting Evidence

  • src/cas_runner/runner.py
  • src/cas_runner/steps/registry.py
  • src/cas_runner/cli.py

Confidence Basis

Empirical implementation across the core engine verified by ratified promotion decisions and automated CI workflow validation.

Consequences

Provides predictable governance and auditability across continuous delivery pipelines while accepting linear step latency.

Benefits

  • Predictable, auditable step order across all runtime and governance workflows
  • Immediate short-circuiting on critical architectural compliance breaches
  • Elimination of uncontrolled autonomous agent execution loops

Risks

  • Throughput degradation during complex multi-hop validation workflows due to strict sequential execution
  • Accumulation of execution time across extensive linear step chains

Governance Implications

  • Enforces deterministic gate checks prior to publishing or committing architectural deltas
  • Mandates explicit registration and verification of all pipeline steps in an authoritative registry

Reuse Notes

Globally applicable to multi-stage agentic evaluation pipelines, architectural compliance runners, and automated CI/CD governance gates requiring fail-fast guarantees.

Confidence

Confidence level derived from ADR decision acceptance and ratified architectural evidence.

Level: low

Rationale

Aligned with the accepted ADR baseline rating, reflecting initial conservative governance confidence while maintaining validated core status.