Task Complexity Routing (SNC)

Priority: P1 (HIGH)

Same ticket label, different engineering difficulty. Score the task, not the label, then route by tier.

Score

Dimension	0	1	2
Spread (how far the change reaches)	one file, one module	several files, one module	cross-module or cross-service
Novelty (new vs existing behavior)	small edit or removal of existing behavior	modify existing logic	new behavior or rewrite
Centrality (how core the touched code is)	peripheral code	shared but non-core	core domain, hot path, auth, money, trust boundary

Sum the three, never average. Output line: SNC: S=[0-2] N=[0-2] C=[0-2] total=[n] tier=[low|medium|high].

Tiers

• tier=low: total 0-2
• tier=medium: total 3-4
• tier=high: total 5-6

Routing

Tier	Autonomy	Verification	Review	Approval	model_tier
tier=low	autonomous	basic: focused tests + lint	fast code-review	none required	fast
tier=medium	guided	TDD + self-review	deep code-review	plan reviewed, no HARD STOP	standard
tier=high	plan-first	TDD + independent reviewers (specialist-architecture-guard, specialist-security-reviewer when relevant)	deep code-review	HARD STOP before code, human approval before merge	strong

Sensitive-Change Risk Floor

Sensitive changes touching authentication, authorization, payments/financial data, data integrity, secrets, or system trust boundaries have an explicit risk floor independent of arithmetic SNC totals:

• Floor: Minimum tier=medium (guided execution, deep review, human plan acknowledgment) even if arithmetic total is ≤2 (e.g. S=0, N=0, C=2).
• High Sensitivity: If spread or novelty is non-zero (S≥1 or N≥1 with C=2), enforce tier=high (plan-first HARD STOP, independent security review, human merge approval).
• Irreversible Actions: Actions involving data destruction, schema drops, credential rotation, privilege escalation, or production cutover strictly require explicit human authorization regardless of tier.

Rules

• Score before planning; emit snc_tier and model_tier in every Handoff Payload.
• Label the score as inference when derived from ticket text alone; re-score after specialist-codebase-scout reports impact radius.
• Round up on doubt. Any auth, money, trust-boundary, or hot-path touch is C=2 and subject to the sensitive-change risk floor.
• Downward complexity reassessment is permitted ONLY with documented new evidence (e.g., scouted blast radius proves isolated scope with verified non-interference), NEVER to bypass unresolved risk, required approvals, or the sensitive-change risk floor.
• Re-score when scope grows mid-task; the tier must rise immediately when expansion is detected.
• Never downgrade a tier to skip a gate. Ticket type (bug vs feature) never sets the tier.

Red Flags

Stop and re-score when hearing or thinking: "it's just a bug fix", "one-line change", "skip the plan, it's small", "we'll review it later", "mark it low so we can merge tonight". Each is a rationalization, not a score.

Anti-Patterns

• No tier by ticket type: "bug" and "feature" say nothing about S, N, or C.
• No averaging: three 1s and one 2/0/1 both route differently only when summed.
• No silent tier: a plan or handoff without snc_tier is incomplete.
• No high tier without named reviewers: tier=high must list which specialists review before merge.

References

• SNC Rubric with Worked Examples
• Routing Table Detail