WEBVTT

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A repeated procedure becomes
easier to reuse when its inputs,

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steps, and output are explicit.

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In this lesson, we will package the
source-checking workflow as a skill.

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The result is a focused directory
containing metadata, instructions,

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and a short supporting reference.
Start with the source discipline

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from Module Four and a preserved
checkpoint-three project.

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We will test runtime
behavior in the next lesson.

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First decide whether a skill
is the right form of reuse.

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A one-off question can stay a prompt.

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General project expectations
belong in AGENTS dot md.

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A deterministic transformation
may belong in a script.

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A skill is useful when a recurring
task needs judgment and a recognizable

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sequence, such as identifying
the exact hardware source,

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extracting relevant constraints,
and explaining missing information.

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Our task is datasheet-to-constraints.

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It should derive interface or
operating constraints for an identified

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board or component using
primary technical material.

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It should not become a universal
embedded-engineering assistant

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that activates for every code
edit and documentation change.

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A narrow purpose makes both the input
contract and the evaluation much clearer.

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Create the dot agents
folder at the project root,

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then skills, then
datasheet-to-constraints.

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CP03 does not yet supply this skill.

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Create the required
file named SKILL dot md.

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The shared Agent Skills specification
describes the package format.

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Codex has its own documented
discovery and invocation behavior.

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Keep those two ideas separate:
a package can be well

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formed while the current host has
not discovered or selected it.

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At the top of the file, YAML frontmatter
sits between delimiter lines.

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The required name should
match the directory,

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using the specification's
lowercase naming form.

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The description should say what task this
skill handles and when it is relevant.

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A phrase such as helps
with hardware is too broad.

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It does not tell the host whether a
README typo or a firmware timing review

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belongs here. Write the
description around the actual task:

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derive constraints for an exact board or
component from supplied primary documents.

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Include a short boundary for unrelated
prose and general coding work.

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Put the useful task words early.
The description is a selection aid,

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not a place for a long sales pitch
or every detail of the procedure.

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Below the metadata, define the inputs.

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We need the exact part or board
identity, the source material,

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and the question the user wants
answered. Preserve the document title,

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publisher, revision when
available, and relevant sections.

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If the revision is absent, the procedure
should say that it is not established.

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A required field must
not pressure the agent

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into inventing a value
just to fill a table.

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Now write the steps as actions an
engineer could perform manually.

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Confirm the identity. Separate chip-level
facts from board-level connections.

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Extract only the constraints
relevant to the request.

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Retain units and conditions.

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Attach a source location
to every supported claim.

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Label any inference and explain its basis.

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Mark unavailable or conflicting
information explicitly,

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then explain what it
means for the project.

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The output contract makes
the result reviewable.

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Use columns for claim, value and
unit, source section or link,

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confidence or missing information,
and design consequence.

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A reviewer should be able to
pick a row, open its source,

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and decide whether the
source supports the value.

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A beautifully formatted row
with an unsupported pin number

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is a failure, even when the
rest of the table is correct.

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Be careful with confidence.

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A numerical percentage can suggest
precision without evidence.

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Phrases such as explicitly documented,
inferred from named facts,

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or not established by the supplied
excerpt are more useful here.

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They explain the basis of the statement.

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An absent pin mapping
should remain absent,

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accompanied by the exact source
or variant needed to resolve it.

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Add a focused supporting reference under
references slash extraction-rules dot md.

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Checkpoint four supplies an
authored example for comparison.

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Your new reference should explain
identity, units, conditions,

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and missing-data handling. Link to it
relatively from the skill directory.

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Check that the file exists
and that the link works.

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A reference that cannot be found
is a defect in the package,

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not useful extra context. Keep
the reference small and relevant.

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Do not copy an entire
manufacturer manual into it.

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Link to primary material and preserve only

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content that the project
has rights to distribute.

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Do not add scripts merely to
make the skill look substantial.

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A deterministic helper can be valuable
later if a repeated check earns

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its maintenance cost, but the first
version can be instruction-only.

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Include one positive example
of uncertainty handling.

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If a source establishes the board family
but not its exact pin mapping, the output

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should mark the mapping unresolved and
identify the missing board reference.

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Also explain the failure case: inserting
a familiar ESP32 pin from memory.

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Even a lucky guess fails the evidence
rule because its claimed support

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does not exist. Review the
finished file in two passes.

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The first checks packaging:
filename, name match,

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YAML delimiters, description,
and relative reference.

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The second checks the procedure:
clear inputs, bounded steps,

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useful output, and honest
missing-data behavior.

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A format validator can
assist the first pass.

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It cannot decide whether a
manufacturer section supports

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a claim or whether the host selected
the skill at the right time.

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Your exercise is to create the
skill or improve one demonstrated

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weakness in a disposable
copy of the supplied version.

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Submit the file, focused reference,
and two anticipated failure cases.

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Preserve earlier work.

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Explain why each proposed step
belongs to this specific procedure

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and which output condition would
make the result unacceptable.

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If you cannot describe failure, narrow
the task before adding more instructions.

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In the next lesson, we will run relevant,
unrelated, and incomplete-input requests.

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That evaluation is what turns a plausible
package into a tested reusable procedure.

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For now, the useful outcome is a small
skill whose purpose and evidence contract

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can be understood without the old
conversation. The structure supports

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reuse while leaving the engineering
judgment visible for review.