| name | idg-section-parallel |
| description | Operationalizes the G5 gated parallel doc-section synthesis mode for IDG. Use when composing a large document (six or more independent sections) routed at the TRANCE tier; fires dependency-layering, bounded per-layer fan-out (up to five subagents), per-section CHT mini-gate, topological-order parent assembly, and provenance merge. Do NOT use for standard-tier or small documents — sequential composition is always the default. |
| metadata | {"methodology":"IDG"} |
Section-Parallel Synthesis (G5)
Operationalizes the G5 form named in the cortex matrix: gated parallel doc-section
synthesis. This is the runnable mode behind the sequential "topological section
order" rule in skills/composition.md. It is TRANCE-gated and never the default —
standard tier always composes sequentially.
Load this skill only when the gate below fires. For small documents it is a no-op.
When to use (gate)
Activate section-parallel synthesis only when all of these hold:
- The document has six or more sections that the skeleton marks as independent
within a topological layer (no section depends on a sibling in the same layer).
- The composition is read-only — IDG never writes source files, so fan-out carries
no write-conflict risk and needs no worktree isolation.
- The caller (cortex/host) routed the task at the TRANCE tier.
Otherwise compose sequentially per skills/composition.md. Small ADRs, runbooks, and
any document with fewer than six independent sections are an explicit no-op — do not
fan out; the coordination overhead is not repaid.
The five steps
1. Dependency-layering
Build the section dependency graph from the skeleton (as in the Draft phase), then
topologically layer it: layer 0 is every section with no unmet dependency; layer 1
is every section whose dependencies are all in layer 0; and so on. Sections within a
layer are mutually independent by construction and may be drafted concurrently.
Record the layering in working memory so the parent can assemble in topological order
later.
2. Bounded per-layer fan-out
For each layer, in layer order, dispatch at most five clean-context per-section
subagents — one section per subagent. Each subagent receives only the source
material relevant to its section (the per-section context budget of
skills/composition.md still applies: ≤ ~2,000 tokens; summarize and cite beyond that).
A subagent runs in a clean context — it sees its section scope, its selected source
slice, and the already-assembled prior layers as read-only reference. It never sees
sibling drafts in its own layer (that is what prevents trajectory cross-contamination).
If a layer has more than five independent sections, batch them: drain five, then the
next five, preserving the per-layer cap. Fan-out is read-only; no subagent writes to
disk and no worktree is created.
3. Per-section CHT mini-gate (one revision max)
Each subagent runs a per-section CHT mini-gate on its own draft before returning it
(see skills/verification.md — two-granularity CHT). Score the section on Completeness,
Helpfulness, and Truthfulness:
- All three ≥ 4 → return the section.
- Any 2–3 → one targeted revision pass on the failing dimension, then return with a
per-section flag note.
- Any 1 → return the section stub with an explicit
[GAP] and the missing-context note;
do not loop.
Hard cap: one revision per section. No subagent re-drafts more than once.
4. Parent assembly (topological-order selection, not averaging)
The parent collects all returned sections and assembles the document in topological
order (layer 0 first, then layer 1, …). Assembly is selection, not averaging: the
parent takes each section as drafted by its subagent — it does not merge or blend two
candidate prose variants into a mean. (IDG drafts each section once per branch; there is
no multi-candidate vote to average. If the host ever supplies redundant drafts of the
same section, the parent selects the higher per-section CHT score and discards the
other; it never concatenates or averages prose.)
Where two sections make claims that conflict, the parent does not silently pick a winner:
it emits a [DISPUTED] marker presenting both, per skills/composition.md.
5. One document-level coherence pass + provenance merge
After assembly the parent runs exactly one document-level coherence check (the
second granularity of the CHT gate): cross-section terminology consistency, transition
bridges between layers, no duplicated or contradictory claims, single provenance block.
The parent then merges provenance: it unions every subagent's per-section source
citations, ECL envelope outcomes, and [GAP]/[DISPUTED] flags into the single
document-level provenance block. Per-section CHT scores roll up to a document-level CHT
line; the coherence pass contributes the document-level Completeness/Helpfulness check.
Stop condition (D5): at most five branches per layer, at most one revision per
section, exactly one parent coherence pass. No further iteration. Deliver with flags.
What this mode does NOT change
- No new write surface. IDG remains read-only; fan-out is concurrent reads +
in-context drafting. No worktree, no file writes by subagents.
- No averaging of prose. Assembly is topological selection; conflicts become
[DISPUTED], never a blended mean.
- No unbounded loops. The per-section one-revision cap and the single coherence pass
preserve IDG's "one gate, one revision max" guarantee at both granularities.
- No default change. Sequential composition stays the standard-tier default; this
mode is gated behind the six-independent-section + TRANCE threshold.
Scribe — Section-Parallel Skill
