Skillscript

Two pure-language additions per Perry's 98d6b60b directive. Both
small, both high author-UX value, both no design tension with existing
carve-outs.

1. |contains:"X" filter

Boolean substring/membership check for use in conditionals. Returns
"true" on match, "" (empty string) on miss — matches the
isTruthy convention in runtime so if ${R|contains:"X"}: evaluates
the way the syntax suggests.

Type-aware with JSON-string tolerance. Mirrors the in / not in
conditional operators per Perry's 4235ef2b pushback during checkpoint:

• LHS resolves to a JSON-parseable array → element membership (each
  element stringified, compared against arg)
• LHS resolves to anything else → substring match on the resolved
  string form

Without type-awareness, ${LIST|contains:"a"} against ["alphabet"]
would silently match (substring "a" inside the stringified
'["alphabet"]') — the discipline-only-contracts shape we've been
closing. Type-aware semantics catch the structural mismatch instead.

Cognitive symmetry: if ${A} in ${L}: and if ${L|contains:"a"}:
return the same answer when ${A} resolves to "a". First filter
to operate on structured types because the conditional primitives
already do; filter-as-conditional-primitive is the design line.
Other filters (|trim, |json, |fallback, etc.) stay string-only.

Common authoring pattern:

$ llm prompt="Reply with 'urgent' if any items are urgent" -> VERDICT
if ${VERDICT|contains:"urgent"}:
    notify(agent="oncall", message="paged")

Replaces the today-fragile shape if ${VERDICT|trim} == "urgent":
which forces the prompt to over-constrain ("EXACTLY one word") just
to fit the equality grammar.

2. Triple-quote textwrap.dedent pattern

Triple-quote literal extraction (parse, escape interpretation,
multi-line spanning, embedded single quotes, ${VAR} interpolation
preservation) was already shipped in the earlier triple-quote work.
This ring adds the missing piece: Python textwrap.dedent whitespace
discipline.

What changes: authors writing multi-line bodies indented inside
the call site (the natural shape) get the common leading whitespace
stripped automatically:

deliver:
    emit(text="""
    Follow these directions exactly,
    step by step,
    without skipping any steps.
    """)

Renders as:

Follow these directions exactly,
step by step,
without skipping any steps.

Three passes:

1. Strip a leading whitespace-only line (the natural """\n body\n """
   shape leaves one immediately after the opening delimiter)
2. Strip a trailing whitespace-only line (same shape leaves one before
   the closing delimiter)
3. Compute the common leading-whitespace prefix across non-empty lines,
   then strip that prefix from each line. Blank-or-whitespace-only lines
   don't constrain the calculation — their indentation is flexible.

Dedent runs BEFORE ${VAR} substitution per the directive's Q1
answer. Authors who substitute multi-line values into a triple-quote
template keep the substituted value's own whitespace; only the
template's literal-body indent gets stripped.

Single-line triple-quote literals pass through unchanged — dedent
only fires when there's actually a newline in the body.

Internal

• src/filters.ts: contains added to KNOWN_FILTERS. applyFilter
  signature extended with optional arg parameter (the existing
  fallback filter consumes its arg upstream, so no other filter
  needed it before).
• src/runtime.ts, src/compile.ts: call-site updates to thread
  spec.arg through to applyFilter. Compile-time substitute regex
  extended to capture the arg.
• src/parser.ts: dedentTripleQuoteBody helper added; applied in the
  triple-quote literal extract branch of processSetValue. Exported
  for direct testing.
• src/help-content.ts: contains: row added to Pipe filters table;
  triple-quote multi-line row added to Kwarg value grammar table;
  dedent semantics example added.
• LOC ceiling nudged 9900 → 10000 to absorb the v0.16 series cumulative
  additions (kwarg lints, manifest exposure, |contains: filter, dedent
  helper, bare-form detection branches). Per Scott's "LOC ceiling is a
  signal not a budget" rule.
• +14 tests in tests/v0.16.6-contains-filter.test.ts (unit + condition
  context + lint integration). +13 tests in
  tests/v0.16.6-triple-quote-dedent.test.ts (unit on the helper +
  end-to-end via emit(text=...) + backward-compat with single-line).
  1511 passing total (was 1484).

Docs

Atom-level updates to the language reference happen separately (owned
by Perry: c6224b7d Ops atom, the Pipe Filters atom, the Planned
section). This ring touches only src/help-content.ts on the runtime
side per agreed split.