State Manager

State File: .arch/state.json

This file is the single source of truth for project progress. ALWAYS read it before responding to architecture queries. ALWAYS update it after state changes.

Reading State

• Parse the JSON file
• Check current_phase to know where we are
• Check phase-specific status fields for detail
• For Phase 2, check sub_phase and individual acceptance flags (pattern_accepted, components_overview_accepted, cross_cutting_accepted)
• For Phase 3, check components object for per-component status
• Check reopens.count and reopens.max for reopen availability

Valid Phase Transitions

not_started → evaluation     (when /analyze-prd runs)
evaluation → methodology     (when Phase 1 is accepted)
methodology → components     (when Phase 2 is fully accepted: pattern + components + cross-cutting)
components → finalization    (when ALL components accepted)

Backward transitions are ONLY allowed via /reopen (max 2 per project).

Phase 2 Sub-Phases

pattern → components_overview → cross_cutting

Each sub-phase is accepted independently via /accept. All three must be accepted for Phase 2 to be complete.

Component Status Values

pending → in_progress        (when /design-component starts)
in_progress → awaiting_acceptance  (when design is presented)
awaiting_acceptance → accepted     (when user accepts)
awaiting_acceptance → in_progress  (when user refines)
needs-review → in_progress         (after a reopen cascades)

Updating State

When updating state.json:

1. Read current state
2. Validate the transition is legal
3. Write the updated state
4. Increment decision_count if a decision was made

Decision Log: .arch/decisions.md

Append-only file. Never edit previous entries. Format:

### [DEC-NNN] Phase X | Category
- **Decision:** [What was decided]
- **Rationale:** [Why this choice]
- **Alternatives:** [What else was considered]
- **Trade-offs:** [What was sacrificed]
- **Risk:** [Any residual risk]
- **Supersedes:** [DEC-NNN — only if this replaces a previous decision]
- **References:** [FR-NNN, DEC-NNN — only if tracing to requirements or cross-cutting decisions]
- **Date:** [ISO timestamp]

Categories: Requirements | Pattern | Technology | Integration | Security | Infrastructure | Process | Reopen

Supersedes and References are optional. Omit the line entirely when not applicable.

Supersession and Traceability Fields

Supersedes — Use when a decision replaces a previous one:

• /reopen creates a new decision that supersedes the original acceptance decision for the reopened target
• /alternative creates a new decision that supersedes the previous proposal's decision
• Format: **Supersedes:** DEC-003 (single) or **Supersedes:** DEC-003, DEC-007 (multiple)
• NEVER edit the superseded entry — the new entry points backward (like RFC "Obsoletes:" fields)

References — Use when a decision traces to requirements or earlier decisions:

• Phase 3 component technology decisions should reference the FR-NNN requirements they satisfy
• Phase 3 component decisions should reference applicable DEC-NNN cross-cutting decisions from Phase 2C
• Phase 2 acceptance decisions should reference the FR-NNN requirements that drove the pattern choice
• Refinement decisions should reference the DEC-NNN of the original proposal being refined
• Format: **References:** FR-001, FR-003, DEC-005

Example — supersession (reopen scenario):

### [DEC-012] Phase 2A | Reopen
- **Decision:** Reopened architecture pattern selection
- **Rationale:** New compliance requirement invalidates serverless approach
- **Alternatives:** Could have added compliance layer on top of existing pattern
- **Trade-offs:** Progress reset on 5 items
- **Risk:** Reopens remaining: 1 of 2
- **Supersedes:** DEC-004
- **Date:** 2026-03-11T14:00:00Z

Example — traceability (component design):

### [DEC-015] Phase 3 | Technology
- **Decision:** Selected PostgreSQL 16 for order-service data store
- **Rationale:** ACID compliance required for financial transactions; team has production experience
- **Alternatives:** MongoDB 7 (flexible schema but lacks native ACID), CockroachDB 24 (distributed but overkill)
- **Trade-offs:** Schema migrations required; less flexibility than document store
- **Risk:** Single-node bottleneck if order volume exceeds 50K TPS
- **References:** FR-003, FR-012, DEC-008, DEC-009
- **Date:** 2026-03-11T15:30:00Z

Automatic Logging Events

Log a decision entry for:

• Phase acceptance
• Phase transition
• Sub-phase acceptance (2A, 2B, 2C)
• Technology selection (per component)
• Refinement requests (what changed and why)
• Alternative requests (what was replaced)
• Review findings (significant concerns raised)
• Reopen operations (with cascade details)