Synthesize: Distill a Spine-Led Gist from One or More Sources

Distill the through-line of one or more sources — a set of documents, or the ideas within a single rich piece — into a short, spine-led gist: a few tight paragraphs built around a spine drawn from the material, where support is insight on its own and the reader is pointed to the source, not served a copy.

Inform the user when invoking this skill by name: synthesize.

Two modal failure modes pull against this and both reassert at draft time, even after a spine is chosen — defeating them is the whole job, not a one-time setup step:

• Listicle — an enumerated march through themes; the model's reflex for "synthesize."
• Fluff — padded coverage that reproduces sources instead of distilling them.

A spine is an internal organizing frame — a constraint, a claim, a recurring metaphor, or a tension — that the material carries: one source among several states it and the rest support it, or one thread runs through the ideas of a single piece. It must come from the material, not be imposed over it (stages of grief, a narrative arc). See references/finding-the-spine.md.

When Not to Use

• Faithful summary or condensation — covering what a source says, proportionally, with no through-line.

That is summary, not synthesis, whether the input is one source or many.

• Comparisons or catalogs where enumeration _is_ the deliverable (vendor capability matrix, feature comparison).

The list is correct; do not force prose. This is the escape hatch — name it and step aside.

• Line-editing or polishing prose — use good-prose, electively, after the gist exists.

Core Discipline

• Gist, don't cover.

The output is at most a few paragraphs — the more concise the better. Comprehensiveness is the enemy; leave out everything the spine doesn't need. The gist is what survives ruthless trimming.

• Support is insight, not reproduction.

Every sentence of support must carry insight on its own; point the reader to the source rather than reproducing it. But surface the gem: a quote, table, or figure that is _itself_ distilled insight — high-signal, stands alone, serves the spine — is the support, not coverage creep; reproduce it. The test: does reproducing it carry the insight, or merely relay content the reader could skim for?

• The spine carries the argument; sources serve the spine, not the reverse.
• Each source earns its place under the spine; those that don't fit are named as exclusions, not crammed in.
• Self-interested sources don't get the last word.

When a source is promoting its own result, product, or position (vendor PR, a lab announcing its own work, marketing), offer a grounding pass before committing the spine — external context to restore the caveats it downplays. Surface the offer; fold outside context in only when flagged and grounded, never silently. External context enters _only_ through this gated pass — not a license to pad with background. See references/finding-the-spine.md.

• Re-grounding old wisdom in new rationale is legitimate synthesis — don't prune it.

Naming the rationale shift _is_ the synthesis; the shift is load-bearing, not the practice's novelty.

• Strip affect that doesn't serve the argument; keep affect that does.

Workflow

1. Intent gate — _narrated checkpoint._

Gist/through-line, faithful summary, or enumeration? Faithful summary → not this skill. Enumeration is the deliverable → step aside (escape hatch). User supplied a spine → short-circuit to 1b.

1. Spine scan — _narrated._

• 1a DISTILL (no spine given) → 1–3 candidate spines from the material (across sources, or the ideas within one).
• 1b VALIDATE (spine given) → test it; verdict may be holds / holds-but-sharpen / amend / doesn't-hold + alternative.
• Self-interest check → source promoting its own result/product/position?

Flag it; offer a grounding pass before step 3 (see reference).

1. Material gate — GATE.

No spine emerged (material doesn't rhyme)? Do not force prose. Offer: synthesizer-POV spine (flagged as a different move) OR hand back.

1. Spine selection — GATE (always).

Confirm the one ("spine = X — good?") · pick among several · re-pick after a validate-reject (user's spine vs the alternative).

1. Build — _narrated, reversible._

A few tight paragraphs on the spine. Support is insight, not reproduction; point to sources. Name exclusions; re-ground old wisdom; cut fluff.

1. Audit & repair — _narrated, reversible._

Check the draft against the failure catalog; repair in place.

Steps 1b (validation with teeth) and 2 (the no-spine branch) are where this skill earns its keep. Read `references/finding-the-spine.md` before running steps 1–3 — the validation verdicts and the no-spine branch live there; running them from memory loses the teeth.

Steering Contract

The user always drives — they can override at any fork, guaranteed by transparency and reversibility, not by the agent stopping for sign-off at every step. The _kind_ tag on each workflow step marks which is which: GATE steps stop for the user before acting; the rest narrate and proceed, reversible by the user's next turn. Surface every consequential choice (the spine, the no-spine fallback, the grounding-pass offer) _before_ acting on it; never commit to a spine silently.

The spine is the single most expensive thing to get wrong — everything downstream hangs off it — so step 3 gates even when there is one obvious candidate.

Audit Catalog (Step 5)

Read `references/audit-failure-modes.md` for detection cues and fixes; repair each in place. The list below is an index, not the procedure — the cues that catch each mode live in the reference.

• Listicle relapse — drifted back to enumerated themes/practices.
• Coverage creep / fluff — sprawled into comprehensive summary, or padded; support reproduces sources instead of distilling insight.
• Abandoned framing — an organizing image in the intro that doesn't carry through.
• Quote-as-spine — a source's quote doing the argumentative work the synthesizer should do.
• Significance inflation — "striking," "the strongest convergence," superlatives standing in for argument.
• Source taken at face value — a self-interested source's spin survived into the gist; caveats it downplays are missing.
• Forced-fit spine — material crammed under a spine it doesn't support (watch this after validate mode).
• Over-pruned wisdom — an old practice dropped instead of re-grounded in its new rationale.

Composition With Other Skills

Standalone — no built-in gather or polish steps, and no automatic handoffs. The user or agent may electively run mcp-research (gather sources) before, or good-prose (polish prose) after.

References

• references/finding-the-spine.md — distill vs. validate modes, validation with teeth, the no-spine branch, source-earns-its-place.
• references/audit-failure-modes.md — each failure mode with detection cues and repairs.