Deprecation Agent Skill

deprecation — removal is a consumer migration

Deprecation is not a date in a changelog. It is the controlled transfer of real consumers from an old contract to a supported replacement, followed by evidence that removal no longer breaks anyone important.

This skill owns the cross-consumer program. It delegates the replacement interface to ../api-design/SKILL.md, live schema mechanics to ../db-migrations/SKILL.md, release/version mechanics to ../git-workflow/SKILL.md, and rollout/rollback execution to ../deployment/SKILL.md.

The retirement sequence

INVENTORY → CLASSIFY → ENABLE → NOTIFY → MIGRATE → OBSERVE → REMOVE

1. INVENTORY the contract and consumers

Identify:

• exact endpoints, events, schemas, flags, SDK methods, jobs, services and docs being retired;
• internal and external consumers, owners and contractual notice periods;
• traffic/usage by consumer, version and operation;
• data written only by the old path and compatibility obligations;
• support, reseller or offline consumers invisible to runtime telemetry;
• current fallback and restoration options.

“No known users” is not an inventory. Query telemetry, code search, dependency graphs, access keys, support records and account owners. Record where visibility is incomplete.

2. CLASSIFY the migration

• Advisory: the old path remains supported; migration is encouraged for benefit or future-proofing.
• Compulsory: support will end or continued use creates unacceptable security, reliability, legal or operating risk.

Only compulsory migrations justify a removal deadline. State the forcing reason and who has authority to accept exceptions. A deadline should respect contracts, effort and evidence; do not import a universal 30/60/90-day calendar.

3. ENABLE migration before announcing removal

The replacement must be usable first:

• compatible contract or adapter where feasible;
• migration guide with old → new mappings and changed semantics;
• tooling, codemod, SDK or dual-write/read path for repetitive work;
• test/sandbox path and representative examples;
• rollback or temporary compatibility mode;
• ownership for data backfill and reconciliation.

For database changes, use expand → backfill → switch reads/writes → contract through ../db-migrations/SKILL.md. Do not promise a generic down migration for irreversible data transformations; prove the actual restoration/reconciliation path instead.

4. NOTIFY through machine and human channels

Use the channels the consumer will actually see: response headers, compiler/runtime warnings, API dashboards, release notes, direct account contact, support and status communications. A warning must name the replacement, action, consequence, evidence link and earliest removal condition.

Versioned public APIs should follow their compatibility policy and SemVer where it applies. Machine warnings without a migration guide create noise; an email without runtime identification misses the real owner. Use both when the surface permits.

5. MIGRATE with explicit ownership

The team introducing the deprecation owns the common migration path: inventory, docs, automation, default internal consumers and escalation. Consumer teams own domain-specific acceptance and scheduling, not rediscovering the replacement.

Track each consumer as: uncontacted, acknowledged, testing, migrated, exempted with expiry, unreachable, or blocked. Give blockers an owner and next action. Reseller-managed or unknown consumers need a separate reachability plan; do not silently exclude them from the denominator.

6. OBSERVE real cutover

Instrument old-path usage by consumer and operation, plus errors on the replacement. Where risk warrants it, shadow or dual-run and compare results before switching authority. Dashboards must distinguish legitimate residual traffic, retries and synthetic probes from active dependency.

Define the removal gate up front, for example:

• no non-exempt production use for a representative window;
• every contractually covered consumer notified and migrated or explicitly exempted;
• replacement error/SLO health acceptable;
• rollback/compatibility response tested;
• support, docs and on-call ready for late discoveries.

The representative window depends on consumer cadence. A monthly batch needs more than a quiet week.

7. REMOVE in a reversible order

Disable entry first, observe, then delete implementation, flags, compatibility code, credentials, dashboards and documentation that exist only for the old path. Preserve audit/history records. Update dependency and ownership maps so the retired system does not remain a zombie operational obligation.

If unexpected material traffic appears, re-enable the bounded compatibility path and return to migration. Do not restore an undocumented permanent fork.

Deprecation record

# Deprecation — <old> → <replacement>

## Classification and reason
Advisory/compulsory · forcing reason · authority · notice constraints.

## Inventory
Contracts · consumers · owners · baseline usage · visibility gaps.

## Migration path
Compatibility · guide/tooling · data plan · rollback/reconciliation.

## Consumer ledger
Consumer · state · owner · last old-path use · blocker/exception expiry.

## Removal gate and evidence
Window · zero-use evidence · replacement health · support/rollback readiness.

## Removal log
Disabled · observed · deleted · residual artifacts.

Anti-patterns

| Smell | Correction |

|---|---|

| The calendar arrives while material traffic remains | Hold removal; the gate is evidence, not date alone. |

| Every consumer writes the same adapter | The deprecating team owns common tooling and default migrations. |

| Internal code search proves external zero-use | Combine runtime identity, contracts, support and account ownership. |

| Temporary compatibility has no owner or expiry | Track an explicit exception with accountable owner and end condition. |

| Deprecation silently grants deploy authority | Keep live rollout/rollback explicit through deployment. |

Orientación (siempre)

Cierra cada turno con el bloque-brújula (📍 dónde estás · ✅ qué hiciste · 🧭 por qué · ➡️ siguiente, terminando en pregunta), calibrado al dial de 02-DOCS/wiki/harness/user-profile.md. Nunca termines en seco. Protocolo completo: skill orient → skills/orient/references/orientation-contract.md. (Defiere a suggest el “¿instalo la skill que falta?”.)