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<background_information> Implements WORKFLOW §4 + §5 end-to-end as one research pass. The four sources are joined by AND, not OR — every non-trivial change runs the full research pass, then synthesizes a happy path, then justifies any deviation. Output is the input to whatever skill or freeform turn produces the implementation plan; this skill does not write code.

Codex auto-trigger on description keywords is less mature than Claude Code's. If auto-invocation does not fire on a non-trivial change, invoke this skill manually before implementing. </background_information>

Step 1 — four-source research pass, all four required:

Source A — official documentation. For each language and library in scope, cite the canonical doc URL and version. Read the relevant section. Ask the user for a known-good link rather than fabricating one. Output: bulleted citations, one per language/library, each with URL plus a one-line summary.

Source B — validated implementation references. ≥1 (prefer 2–3) public reference (open-source repo, Stack Overflow / forum answer, blog post, gist) solving the same technical research scope with similar techniques. Match is technical, not domain. Cite <source>:<locator> — <repo>:<path>:<line-range> for repos, <URL> for Stack Overflow / forum / blog / gist — and quote the relevant block. Never paraphrase from training memory. If search is inconclusive, ask the user for a known reference.

Source C — in-repo examples. Grep / glob for analogous patterns. Cite <file>:<line> plus a one-line description of how the existing example handles the same shape. If the codebase has no analog, state that explicitly.

Source D — git history. Run git log --all --oneline -- <relevant-paths>, git log --all --grep=<keyword>, sweep sibling active branches. Cite <commit-sha> plus touching file path and a one-line description. If empty, state "no prior attempt found." Narrow with --grep or -S on multi-thousand-commit repos.

Step 2 — happy path synthesis. In one paragraph, name the most-grounded approach for the research scope and cite at least one source per Source A / B / C. Source D included when it produced a hit; otherwise mark "no prior attempt found." The paragraph is the canonical answer to "what is the canonical, idiomatic way to solve this here?"

Step 3 — deviation gate. If the implementation about to be written deviates from the happy path, write the justification first. Must name the specific constraint, evidence, or trade-off forcing the deviation — generic "we want it differently" is insufficient. If the justification cannot be written confidently, loop back to Step 1 and look harder; do not deviate without it. Prescriptive gate, not descriptive — write the answer down.

Step 4 — confidence checkpoint. Soft verdict on:

• A consulted (≥1 official-doc citation per language/library)
• B consulted (≥1 implementation-reference citation, with cite-and-fetched code)
• C consulted (in-repo analog cited or "no analog found" stated)
• D checked (commits / branches surveyed; hit cited or "no prior attempt found")
• Happy path declared (Step 2)
• Deviation, if any, justified (Step 3)

If any check fails, surface the gap to the user and ask before proceeding. Do not block. The user retains authority to skip; the discipline is in surfacing.

<output_contract> A single message structured as:

## Recortte
<one sentence>

## Source A — official documentation
- <lang/lib>: <URL@version> — <one-line summary>

## Source B — validated implementation references
- <repo>:<path>:<line-range> — <one-line summary>   # repo form

Source C — in-repo examples

• : —
• (or: "no analog found in the codebase")

Source D — git history

• —
• (or: "no prior attempt found")

Happy path

<one paragraph synthesizing A + B + C + D, with citations>

Proposed implementation vs happy path

• aligned:
• deviates:
  • :

Confidence checkpoint

• A consulted: yes / no —
• B consulted: yes / no —
• C consulted: yes / no —
• D checked: yes / no —
• happy path declared: yes
• deviations justified: yes / no / n.a.