Source Grounded Development Agent Skill

source-grounded-development — make current facts part of the change

Use this when correctness depends on what a framework, SDK, API, standard or hosted platform does now for the exact version in this repository. The deliverable is still code, a review or an implementation decision; sources are the evidence behind it, not a separate essay.

This is narrower than ../research-ops/SKILL.md: research-ops answers an open question with a cited memo. Here, the question exists because a concrete change cannot safely proceed from memory.

The loop

DETECT → QUESTION → SOURCE → APPLY → PROVE → REPORT

1. DETECT the actual version and environment

Read the repository before the web:

• lockfiles and manifests, not only a README;
• runtime and compiler configuration;
• generated client/server versions;
• deployment target and enabled compatibility flags;
• existing wrapper code that may override documented defaults.

Record an evidence line such as: Next 16.2.1 from pnpm-lock.yaml; Node 24 from .nvmrc; App Router; deployed to Vercel. If versions conflict, stop treating the docs as applicable until the conflict is resolved.

2. QUESTION only the claims that can change the implementation

Build a small claim ledger. Each row is one decision-sensitive statement:

claim | exact component/version | evidence needed | source | applicability | status

Examples: whether a callback is invoked on retry, the default cookie policy, an API’s idempotency semantics, a deprecated option’s replacement, or a browser feature’s support boundary. Do not cite obvious local code or generic programming facts just to make the list longer.

3. SOURCE by authority and freshness

Prefer, in order:

• the repository and installed type definitions for local truth;
• official versioned documentation and migration/release notes;
• specifications, RFCs or provider API references;
• upstream source or tests when documentation is ambiguous;
• reputable secondary material only as a lead, never as the final authority for a disputed behaviour.

Use the current page that matches the detected version. A search snippet, an undated blog, a forum answer or remembered API shape is not proof. When two primary sources disagree, show the disagreement and test the behaviour; do not average them into false certainty.

4. APPLY the source to this repository

For every useful source, state why it applies here:

• same major/minor version or a documented compatibility range;
• same runtime, router, transport, deployment mode or feature flag;
• no local wrapper/configuration that changes the default;
• publication or update date appropriate to a fast-moving claim.

Then make the smallest implementation decision that the evidence supports. Do not turn examples from docs into architecture by cargo cult. Examples demonstrate an API; the repository still determines ownership, boundaries and error policy.

5. PROVE behaviour locally

Documentation tells you intended behaviour. A local test proves the integration:

• add or run a focused contract/regression test;
• compile against installed types;
• exercise a minimal reproduction when defaults or runtime order matter;
• run the stack’s normal verification gate after the focused proof.

If local evidence contradicts the source, preserve the reproduction and investigate version/config drift. Do not silently choose whichever result is more convenient.

6. REPORT without polluting the code

End with:

• versions and environment detected;
• material claims verified and their primary links;
• implementation choices those claims changed;
• local evidence run;
• assumptions still UNVERIFIED, with the consequence if wrong.

Put source links in the final report, PR description or a durable decision record when the rationale must outlive the task. Do not scatter documentation URLs through source comments unless the code’s invariant genuinely cannot be understood without that external contract.

Stop conditions

Stop searching when every decision-sensitive claim is verified, contradicted or explicitly marked unverified and the local proof is green. Search breadth is not quality. A fifth article repeating the official reference adds no evidence.

Do not use this skill as a reason to delay reversible work indefinitely. If a primary source is unavailable, name the uncertainty, choose the safest reversible option, add a proof/guard, and state what would trigger revisiting it.

Anti-patterns

| Smell | Correction |

|---|---|

| A reproduced bug is replaced by a docs tour | debug owns diagnosis; use this only for the disputed versioned claim. |

| A broad open question is forced into implementation | Route the cited memo to research-ops. |

| A lasting architecture choice disappears into a task summary | Preserve it in decision-records with this ledger as evidence. |

| A search result or secondary article is presented as official | Follow it to the primary source or mark the claim unverified. |

| “Latest docs” are read before the lockfile | Detect the local version and mode first; then choose applicable docs. |

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?”.)