Nexus SDLC — Process Architecture Index

Last updated: 2026-03-24

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Decisions

ID	Title	Status	Summary
DEC-0001	Agent Role Taxonomy	Accepted	Thirteen agents across seven planes (Configuration, Control, Analysis/Planning, Design/Structure, Execution, Verification/Security, Delivery). Concern-based separation. Orchestrator as communication hub. Builder-to-Architect direct path as sole exception.
DEC-0002	Lifecycle Phases and Human Gates	Accepted	Five phases (Ingestion, Decomposition, Execution, Verification, Go-Live) with five human gates (Requirements, Architecture, Plan, Demo Sign-off, Go-Live). Three CD philosophy models. Retrospective embedded at Demo Sign-off.
DEC-0003	Agent Communication and Routing Protocol	Accepted	Hub model — all communication routes through the Orchestrator. Structured markdown artifacts at conventional file locations. Ubiquitous language. Builder-to-Architect direct path. Merges former DEC-0003 (Handoff Protocol) and DEC-0007 (Communication Standards).
DEC-0004	Artifact Trail as Project State	Accepted	Project state is a collection of markdown files at conventional locations, versioned by git. Methodology Manifest as swarm configuration. No single monolithic document. No software runtime.
DEC-0005	Tool Access Tiering and Blast Radius Control	Accepted	Five-tier model (Read and Reason, Scoped Write, Command Execution, Restricted, Human-Gated). Declared, not enforced — behavioral constraints in agent prompts plus human capability gating.
DEC-0006	Escalation Protocol and Failure Mode Taxonomy	Accepted	Ten failure modes with defined detection and response. Nexus Briefing format for all escalations. One question per escalation (DEC-0009). Escalation log as audit trail. Two production incident tracks (next-cycle, hotfix).
DEC-0008	Hybrid Swarm Pattern	Accepted	Hybrid pattern: Agile core (XP execution), Formal gates (RUP milestones), Empirical adaptation (Scrum process control), Human-centric communication (Crystal). Dominant methodology varies by phase. Per-project adaptation via Methodologist.
DEC-0009	Iterative Approximation Principle	Accepted	The system makes forward progress on partial, approximate input. Never block on perfect information. Prefer proposals over interrogations. One question at a time.
DEC-0010	Agent Definition File Format	Accepted	Single markdown file per agent. Self-contained, LLM-agnostic, human-readable. Canonical structure: Identity, Flow, Responsibilities, You Must Not, Input/Output Contracts, Tool Permissions, Handoff Protocol, Escalation Triggers, Behavioral Principles, Profile Variants.
DEC-0013	Project Profile Naming	Accepted	Four profiles by stakes (Casual/Commercial/Critical/Vital) with four artifact weights (Sketch/Draft/Blueprint/Spec). Self-describing in plain language.
DEC-0014	The Methodologist Role	Accepted	Standing role active throughout project life — not a one-shot bootstrap. Configures the swarm initially, then re-activates on triggers (phase end, team change, scope shift) to run retrospectives and update the versioned Methodology Manifest.
DEC-0015	Ingestion Loop Design	Accepted	Ingestion is a multi-pass cycle: Analyst -> Auditor -> Nexus clarification -> Analyst revision -> repeat until clean. Demo feedback re-opens ingestion with regression check.
DEC-0016	Decomposition Phase and Gates	Accepted	Two gates (Requirements + Plan) with Architecture Gate between them. Approval criteria: risk-driven + value-driven. [DEFERRED] flag for conscious deferrals. Architect artifacts by profile: metaphor/sketch -> Overview -> ADRs -> ADRs + Baseline.
DEC-0017	Fitness Functions as Dual-Purpose Specifications	Accepted	Every architectural characteristic has a dual-use fitness function: dev-side check (Verifier) + production monitoring threshold + alarm meaning. Architect defines both. Scales to profile.
DEC-0018	Spike Task Ownership and Lifecycle	Accepted	Architect identifies the unknown, writes the acceptance criterion, runs the investigation, produces the finding. Planner schedules before dependent tasks. Planner re-estimates affected tasks.
DEC-0024	DevOps Phased Invocation	Accepted	DevOps invoked in three just-in-time phases at Commercial+: Phase 1 (CI pipeline, dev environment, Environment Contract) before first Builder task; Phase 2 (staging, CD pipeline) after first Verifier PASS; Phase 3 (production, monitoring, rollback verification) before Go-Live gate. Planner tags tasks by phase; Orchestrator enforces sequencing.
DEC-0023	Backward Cascade Protocol	Accepted	When an Architecture Gate rejection changes a foundational assumption (delivery channel, deployment model, auth model, data persistence, system boundary), the Orchestrator triggers a backward impact check: Auditor checks approved requirements for invalidated acceptance scenarios ([INVALIDATED] flag); if found, Analyst revises before gate is re-attempted. Scoped to foundational assumptions only — not all revisions.
DEC-0022	Cycle as Unit of Delivery	Accepted	A cycle is a Planner-defined subset of the backlog forming a coherent, demonstrable increment. The Planner declares cycle boundaries explicitly in the Task Plan. The Orchestrator executes only the current cycle’s tasks before Demo Sign-off. Nexus approves the cycle boundary at the Plan Gate. No timebox — scope-based boundary.
DEC-0021	Context Exhaustion Checkpoint Protocol	Accepted	When a session approaches context exhaustion, the Orchestrator writes a self-sufficient checkpoint to process/orchestrator/project-state.md before the session ends. On resume, the Nexus uses the continuation prompt to invoke the Orchestrator in verification mode. The checkpoint must be readable cold with no access to the prior conversation.
DEC-0020	Commit Policy	Accepted	One commit per task. Verifier is sole committer, after full PASS + clean regression. Builder never commits. Commit pushed to remote; CI green required if pipeline configured. Commit message: TASK-NNN: <description> — all tests pass. Replaces the pilot approach of a single manual Nexus commit at Go-Live.
DEC-0019	Acceptance Test Authorship Chain	Accepted	Analyst’s GWT scenarios are the minimum required test coverage. Verifier MUST implement all Analyst-drafted scenarios as executable tests. Verifier MAY add additional negative, boundary, and edge-case tests beyond the Analyst’s scenarios; any such test is tagged [VERIFIER-ADDED] in the test name or immediately above the test function.
DEC-0025	Planner Multi-Pass Invocation	Accepted	Initial Planner invocation for a cycle is split into three focused Orchestrator-managed passes: Pass 1 — decomposition (atomic tasks, acceptance criteria); Pass 2 — scoring and ordering (risk/value rubrics, priority matrix, cut line); Pass 3 — release map (MVP boundary, rolling confidence). Revision invocations (spike, demo feedback, mid-cycle change) remain single-pass. Prevents LLM cognitive overload on a ~700-line agent definition.
DEC-0026	Sentinel Sequential Timing	Accepted	Sentinel runs once per cycle, after all tasks in the cycle have passed Verifier — not alongside Verifier per task. Sentinel requires a stable, fully verified build and the Verifier’s test results as input. Sequential ordering eliminates interference between security probing and functional test runs against the same staging environment.
DEC-0027	Process Metrics Collection	Accepted	The Orchestrator maintains a Process Metrics section in process/orchestrator/project-state.md as a running tally (Commercial and above): auditor pass counts, gate rejection counts, average iterations to PASS, tasks hitting max iterations, escalation count, backward cascade events. The Methodologist reads this section as primary quantitative input to the retrospective.
DEC-0028	Convergence Signal Evaluation	Accepted	The Orchestrator tracks failing acceptance criterion counts per Builder-Verifier iteration in the Iterate Loop State. If the count has not decreased for the number of consecutive iterations defined as the convergence signal in the Manifest, the Orchestrator escalates to the Nexus before the next Builder iteration — not after the hard limit. Escalation includes the failure count trend.
DEC-0029	Technical Observations Routing	Accepted	Verifier non-blocking observations (architectural concerns, stale docs, fragile patterns) are collected by the Orchestrator at cycle completion and surfaced in the Demo Sign-off Briefing’s Technical Observations section. They do not block sign-off. If the Nexus chooses to act on an observation, it enters the normal demo feedback channel through the Analyst.
DEC-0030	Skills Framework	Accepted	A skill is a reusable procedural document in skills/ that an agent references to execute a specific capability. Skills are LLM-agnostic markdown, loaded into agent context by the Nexus when relevant. Agent definitions reference skills by name in their Responsibilities or Profile Variants sections. Skills are capability-specific and profile-neutral unless the skill itself declares profile restrictions.
DEC-0031	Post-Deployment Smoke Test	Accepted	After every production deployment, DevOps runs a two-stage verification before the Go-Live gate closes: infrastructure health check (fail-fast, automated rollback on failure) then application-level smoke suite sourced from Verifier’s Demo Scripts tagged smoke: true. Smoke failure halts without rollback and escalates to the Nexus. Profile-scaled: Casual health-check only; Commercial minimum 1 scenario; Critical/Vital full suite.

Open Questions

Resolved

ID	Title	Status	Resolution
OQ-0001	Specification Grounding	Resolved	Assume-and-flag mode. Planner makes working assumptions, flags them, proceeds, refines on feedback. See DEC-0009.
OQ-0002	Loop Termination Signals	Resolved	Three structural defenses in agent definitions (directory partition, test immutability, mandatory negative cases + pre-PASS self-check). DEC-0028 adds convergence signal detection (non-decreasing failure count triggers early escalation). Remaining open items (mutation testing at Critical/Vital, dual verification) deferred to pilot phase — do not block current work. Demo Sign-off is the final human defense against semantically wrong implementations.
OQ-0003	Context Loading Strategy	Resolved	Resolved by Option A: the Orchestrator’s Routing Instruction includes a “Load these artifacts” field for each agent invocation. The Nexus follows the Routing Instruction. Empirical calibration of exact artifact subsets is deferred to pilot; Input Contracts and Routing Instructions are sufficient for current design-phase work.
OQ-0005	Technology Stack	Resolved	No software runtime. The deliverable IS the agent definition files — structured markdown prompts loaded into any LLM. See DEC-0010.
OQ-0006	Orchestrator Implementation	Resolved	The Orchestrator is an agent definition file. The human is the runtime. Orchestration logic is encoded as behavioral instructions in the prompt.
OQ-0010	Builder Session Definition	Resolved	Resolved by Option C: task atomicity is kept as a heuristic (“one demonstrable outcome, one coherent change to the codebase”). Builder agent definition includes an escalation trigger for tasks that appear to require more than one logical implementation step. Planner splits on Builder’s signal. Empirical calibration deferred to first pilot.

Critical Priority

ID	Title	Status	Summary
OQ-0011	Fitness Function Source of Truth	Resolved	ADR (or Architecture Overview) is authoritative for each fitness function’s definition and rationale. fitness-functions.md is a generated index maintained by the Architect — not independently authored. Planner and Verifier enumerate from the index and follow pointers for context. See DEC-0017.
OQ-0012	Scaffolder Handoff Routing	Resolved	Scaffold Manifest routes to the Builder, not back to the Planner. The Planner’s task decomposition is complete before the Scaffolder is invoked. The Manifest is reference material for the Builder (what exists, interfaces, dependency order). Routing it back to the Planner would create a circular dependency.

High Priority

ID	Title	Status	Summary
OQ-0004	Trust Calibration	Open	How the Nexus develops calibrated trust in agent output over time. Demo Sign-off gate (explore running software) partially addresses this.

Medium Priority

ID	Title	Status	Summary
OQ-0007	Evaluation Harness Design	Open (Reframed)	How to measure quality of a prompt-based, human-runtime framework. Covers prompt review, dogfooding, scenario evaluation, and regression through diffing.
OQ-0009	Retrospective by Profile	Open	What a Methodologist retrospective produces at each profile level. Methodologist triggers are defined; per-profile output format is not.

Low Priority

ID	Title	Status	Summary
OQ-0008	Multi-Project Isolation	Open	Context isolation strategy when the Nexus runs the framework across multiple concurrent projects.
OQ-0014	RATIONALE.md Maintenance Policy	Resolved	RATIONALE.md is a design rationale document — explains why the framework exists and what principles drive it. It is not a living specification. Authoritative current-state sources are agents/*.md, the Methodology Manifest, and process/INDEX.md. Update RATIONALE.md at major milestones only (role changes, new design goals, principle changes) — not on individual agent refinements. A one-time correction pass to fix identified drift points is deferred to after the audit resolution session.
OQ-0013	Configurable VCS Workflow	Open (Deferred)	Which version control workflow to use — trunk-based, Feature Branch Workflow, Git Flow, or other. Currently the framework assumes a single working branch. Feature branches per task would enable PR-based review for larger teams; Git Flow or similar would add release branches. Resolve before first multi-developer pilot. The Methodologist Manifest may be the right place to declare the chosen workflow, with downstream impact on Verifier commit/push instructions and DevOps pipeline configuration.
OQ-0015	Production Feedback Loop	Open (By Design)	The production feedback loop is open by design. The framework’s responsibility ends at Go-Live. The Architect’s fitness functions and DevOps monitoring configuration are the handoff artifacts that enable human operators to detect issues in the live system. When issues surface post-deployment, a human operator raises them to the Nexus, who re-engages the swarm through the normal channel (production incident or new requirement). The swarm does not stay active between development cycles. This is not a gap — it is a deliberate design boundary consistent with the Human-in-the-Middle principle.

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Dependency Map

DEC-0010 (Agent File Format) ──blocks──> Writing any agent definition file

DEC-0013 (Profile Naming) ──used by──> DEC-0008 (Hybrid Swarm per-project adaptation)
                           ──used by──> DEC-0014 (Methodologist Manifest output)
                           ──used by──> DEC-0010 (Profile Variants section in every agent file)
                           ──used by──> All agent artifact production

DEC-0014 (Methodologist)  ──produces──> Methodology Manifest
                           ──configures──> Orchestrator agent (DEC-0001 Control Plane)

DEC-0008 (Hybrid Swarm)   ──informs──> DEC-0002 (methodology per phase)
                           ──informs──> DEC-0014 (Methodologist adaptation logic)

DEC-0001 (Role Taxonomy)  ──defines──> DEC-0003 (who communicates with whom)
                           ──defines──> DEC-0005 (which tier per agent)
                           ──defines──> DEC-0006 (who detects and routes each failure mode)

DEC-0003 (Communication)  ──defines──> DEC-0004 (artifact locations and formats)
                           ──defines──> DEC-0006 (escalation format as Nexus Briefing)

DEC-0009 (Iterative Approx) ──constrains──> DEC-0006 (one question per escalation)
                              ──constrains──> DEC-0015 (Auditor asks one question at a time)
                              ──constrains──> All agent Escalation Triggers sections

DEC-0002 (Lifecycle)       ──structures──> DEC-0015 (Ingestion loop within lifecycle)
                           ──structures──> DEC-0016 (Decomposition within lifecycle)
                           ──structures──> DEC-0017 (Fitness functions within ADR cycle)
                           ──structures──> DEC-0018 (Spikes within decomposition)

OQ-0002 (Loop Termination) ──may revise──> DEC-0002 (iterate convergence criteria)
OQ-0003 (Context Loading)  ──informs──> Orchestrator Routing Instruction format
OQ-0004 (Trust Calibration) ──informs──> Demo Sign-off Briefing format in Orchestrator agent file
OQ-0009 (Retrospective)   ──informs──> Methodologist per-profile retrospective output

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Deleted Documents

Former ID	Former Title	Disposition
DEC-0007	Communication Standards	Merged into DEC-0003 — artifact types, ubiquitous language, and structured markdown formats are now part of the unified communication protocol decision.