book-mirror — Personalized Chapter-by-Chapter Book Analysis

Convention: see _brain-filing-rules.md for the sanctioned media/<format>/<slug> exception this skill files under.

Convention: see conventions/quality.md for citation rules, back-link enforcement, and output quality bars.

Convention: see conventions/brain-first.md for the lookup chain (brain → search → external) the context-gathering phase follows.

What this does

Given a book (EPUB or PDF), produce a brain page where every chapter is summarized in detail on one side ("The Chapter") and mirrored back to the reader's actual life on the other ("The Mirror"), using their own words, situations, people, and patterns from the brain. Output is a brain page at media/books/<slug>-personalized.md.

This is NOT a generic book summary. The mirror is the value: it makes the book read like a smart friend who happens to know the reader's life deeply is pointing things out in the margins. The mirror's job is recognition — "that's exactly me" — and then getting out of the way. If the user wants a flat summary instead, route them to a different skill.

Trust contract (read this before running)

book-mirror runs as a CLI command (gbrain book-mirror), NOT as a pure markdown skill that the agent dispatches via tools. The CLI is the trusted runtime; the skill is the orchestration prose around it.

What this means for the agent:

• The CLI submits N read-only subagent jobs (one per chapter). Each subagent has allowed_tools: ['get_page', 'search'] only. They CANNOT call put_page or any mutating op. They produce markdown analysis via their final message.
• The CLI reads each child's job.result, assembles the final page, and writes it via a single operator-trust put_page.
• This means untrusted EPUB/PDF content cannot prompt-inject any people/* page. The trust narrowing happens at the tool allowlist, not at the slug-prefix layer.

The pipeline

1. ACQUIRE   → User has the EPUB/PDF locally (manual; book-acquisition is
               not currently shipped — see "Acquiring the book" below).
2. EXTRACT   → Pull chapter text from EPUB/PDF into one .txt per chapter.
3. CONTEXT   → Gather everything the brain knows about the reader.
4. ANALYZE   → `gbrain book-mirror` fans out N read-only subagents.
5. ASSEMBLE  → CLI reads each child result and writes one put_page.
6. PDF       → Optional: render via skills/brain-pdf for delivery.

1. Acquiring the book

book-acquisition (legal-grey-area downloader) was deliberately not shipped in this skill wave. The user drops the EPUB/PDF manually. Common paths the user might use:

# User-supplied path
ls path/to/book.epub
ls path/to/book.pdf

# Or already in the brain repo (recommended for tracking)
ls $BRAIN_DIR/media/books/

Resolve $BRAIN_DIR from the gbrain config (gbrain config get sync.repo_path) or accept it from the user.

2. Text extraction

Goal: one .txt file per chapter under a temp directory. The agent has shell + python access; the CLI is downstream of this and takes the extracted directory as input.

EPUB

SLUG="this-book"                                # kebab-case
WORK="$(mktemp -d)/$SLUG"
mkdir -p "$WORK/chapters"
unzip -o path/to/book.epub -d "$WORK/unpacked"

# Find content files (XHTML/HTML), sorted (chapter order = sort order)
find "$WORK/unpacked" -name "*.xhtml" -o -name "*.html" | sort > "$WORK/files.txt"

# Strip HTML to text per chapter
python3 - <<'PY'
from bs4 import BeautifulSoup
import os, sys
work = os.environ['WORK']
files = open(f'{work}/files.txt').read().splitlines()
for i, path in enumerate(files, 1):
    html = open(path, encoding='utf-8', errors='replace').read()
    text = BeautifulSoup(html, 'html.parser').get_text('\n')
    text = '\n'.join(line.strip() for line in text.splitlines() if line.strip())
    with open(f'{work}/chapters/{i:02d}.txt', 'w') as f:
        f.write(text)
PY

If bs4 is missing: pip3 install beautifulsoup4 lxml.

Inspect the chapter files to identify which are real chapters vs front matter (TOC, copyright, acknowledgments). Often the EPUB ships one file per chapter; sometimes multiple chapters per file. Use head -5 "$WORK/chapters/"*.txt to spot-check.

PDF

pdftotext -layout path/to/book.pdf "$WORK/full.txt"

Then split by chapter heading (look for "Chapter N", "CHAPTER N", or all-caps title lines) using awk or python. If the PDF is a scan with no embedded text, fall back to OCR via skills/brain-pdf or another vision tool.

Quality check

For each chapter file:

• Word count > 1500 (typical chapter range 2k–8k words).
• No HTML tags.
• Paragraphs preserved with \n\n.

Save a chapters/INDEX.md mapping chapter number → title → file → word count for reference.

3. Context gathering

This is the most critical step. The mirror is only as good as the context fed to each chapter subagent.

What to pull

1. Templates: USER.md and SOUL.md if the user maintains them (gbrain ships templates at templates/USER.md and templates/SOUL.md; they live in the brain repo when populated). Read full.
2. Recent daily memory — last 14 days of brain pages under wiki/personal/reflections/ or wherever the user files daily notes.
3. Topic-relevant brain searches tuned to the book's themes:
   • gbrain query "marriage", gbrain query "couples therapy" for a marriage book.
   • gbrain query "founders", gbrain query "fundraising" for a business book.
   • gbrain query "shame", gbrain query "anger" for a psychology book.
4. Brain pages for relevant entities — gbrain query "<name>" for people who will likely come up.
5. Standing patterns — anything in the user's reflections or originals that's been recurring.

Deep retrieval (DEFAULT — not optional)

A thin static context pack is the #1 cause of a generic mirror. The quality ceiling is the brain itself, not whatever got manually stuffed into one file. Do per-section retrieval before invoking the CLI:

1. Split the book into sections (chapters, parts, or thematic units).
2. For EACH section, generate 15–20 targeted brain searches based on what the author is saying in that section.
3. Fetch the top brain pages from those searches.
4. Fold the retrieved material into the context pack, grouped by chapter, so each chapter subagent sees the pages that map to ITS section.

Query generation strategy (per section):

• Literal theme match — what is the author literally talking about?
• Psychological parallel — what pattern does this map to in the reader's life?
• Specific incident hunt — what dated events would the author be describing?
• Relationship/people parallel — who in the reader's life maps to this?
• Temporal parallel — what period of the reader's life is closest?

Execution:

gbrain query "QUERY" --limit 3
gbrain get "PAGE_SLUG"

Budget: 15–20 searches per section × N sections, plus 40–60 full page fetches. All local DB queries — essentially free. Target 50–80K chars of retrieved brain context total. The chapter subagents also carry read-only search + get_page tools at run time, so the context pack is the floor, not the ceiling — but do not rely on subagents to rediscover what the orchestrating pass already found.

Minimum retrieved material for a high-stakes mirror:

• 40+ brain pages retrieved across all sections.
• 10+ direct quotes from the reader (verbatim from brain pages).
• Dated incidents and recurring patterns where available.
• Coverage across life domains: journal entries and reflections, work and creative output, relationships, public/civic life, specific joyful moments, cultural identity — not just the heaviest material.

Assemble a context pack

Write everything to a single file the CLI can read:

CONTEXT="$WORK/context.md"
{
  echo "## USER.md (if any)"
  [ -f "$BRAIN_DIR/USER.md" ] && cat "$BRAIN_DIR/USER.md"
  echo
  echo "## SOUL.md (if any)"
  [ -f "$BRAIN_DIR/SOUL.md" ] && cat "$BRAIN_DIR/SOUL.md"
  echo
  echo "## Recent reflections (last 14 days)"
  # Pull recent daily reflections — adapt to the user's filing scheme
  # ...
  echo
  echo "## Topic-relevant brain pages (grouped per chapter)"
  # Deep-retrieval results from above, grouped by the chapter they serve
  # ...
  echo
  echo "## Themes & cruxes"
  # A 1-page summary, written by the agent, calling out:
  # - What's currently active in the user's life that this book intersects
  # - Specific quotes from the user that map to book themes
  # - People and dates that should appear in the mirror
  # - The anti-repetition constraints (domain map + phrase caps, below)
} > "$CONTEXT"

Make this dense. It's read by every chapter subagent. Encode the anti-repetition constraints (next section) here — the per-chapter domain assignment and phrase caps only work if every subagent can see them.

Quality system (hard rules)

These rules were earned through iteration with cross-modal eval. They are mandatory for every book-mirror.

Principle: the Chapter half IS the variety engine

The single most important lesson: rich chapter summaries drive varied mirrors. When you compress the source material, the mirror has nothing to respond to except its own greatest hits. The two halves are symbiotic, not competing for space.

Rule: Every distinct idea, story, framework, numbered list item, and memorable phrase the author presents gets its own section. If the author lists six kinds of loneliness, that's six sections. If they tell three stories, that's three sections. The Chapter half should be detailed enough that someone could skip the book and not lose much. The Mirror half responds to EACH specific idea with a DIFFERENT personal mapping.

Layout: top-aligned HTML tables OR stacked sections (hard rule)

Do NOT emit a bare | The Chapter | The Mirror | markdown pipe table. GitHub (and most renderers) pad a table row's cells to equal height and vertically center the shorter cell's text — so when the two halves differ in length (they always do), one column floats down with a block of whitespace above it. Plain markdown has no per-cell vertical-align. That is the root cause, not a styling nit.

Two valid containers — both are correct, pick by destination:

1. Top-aligned HTML table (the CLI default). The gbrain book-mirror chapter prompt already mandates an HTML <table> with valign="top" on EVERY <td> — this is baked into the trusted runtime. Facts worth knowing when hand-writing or repairing a mirror: GitHub KEEPS valign="top" but STRIPS inline style="vertical-align", and does NOT render markdown emphasis inside a raw <td> — pre-convert emphasis to <em>/<strong>, and use <br><br> for paragraph breaks within a cell.

2. Stacked sections — best for mobile and chat delivery, and the right choice for any hand-assembled mirror (children's variant, retro-fixes of legacy pages):

   ### Chapter N: <title>
   
   **The Chapter**
   
   <chapter prose, normal paragraphs separated by blank lines>
   
   **The Mirror**
   
   <mirror prose, normal paragraphs separated by blank lines>
   

   Use real blank-line paragraph breaks, never <br><br> outside a table cell. Reads top-to-top every time, zero alignment bug. The Chapter/Mirror naming and the one-section-per-idea richness rule are unchanged — only the container changes.

Anti-repetition (hard constraints, not vibes)

"Be more varied" doesn't work as an instruction. LLMs remix the deck they're given — if the deck is 6 cards, you get 6 cards N times. Use hard constraints, written into the context pack's "Themes & cruxes" section:

1. Domain mapping: Before writing, assign each chapter a PRIMARY life domain (career, family, civic work, creative life, a specific relationship, childhood, intellectual life, spiritual practice, etc.). No two adjacent chapters should share the same primary domain.

2. Phrase caps: No word or phrase may appear as a thematic anchor in more than 3 chapters. Identify the reader's "greatest hits" (the 5–6 themes that would dominate without constraints) and set explicit limits or bans.

3. Story deduplication: Before writing each mirror, check: "Have I already used this story/incident/quote in a previous chapter?" If yes, find a different one.

4. Emotional range requirement: At least 25% of chapters must map to JOY, HUMOR, CREATIVE EXCITEMENT, or VICTORY — not only wounds and struggle. When the author describes something beautiful, the mirror should find something beautiful in the reader's life.

The editorial rule (THE MOST IMPORTANT RULE)

Deep retrieval is the engine, not the product. The reader should never feel like they're reading a research paper or a search results page. The mirror must read like a brilliant essay by someone who knows the reader deeply — not a report proving it did homework.

The test: If you remove all citations and source attributions, does the mirror still make the reader feel seen? Does it still produce epiphanies? Does it still work as standalone writing? If yes, the retrieval served its purpose. If the mirror only works because of its citations, the retrieval failed.

Citations: Optional. Use sparingly as footnotes when the source adds genuine value ("you wrote this at 19" lands differently when the reader knows you actually read the journal entry). But never let citations become the point. Never let the mirror read like it's performing thoroughness.

Cross-modal eval gate (recommended for high-stakes mirrors)

After generating a mirror, run gbrain eval cross-modal (or the manual gate in skills/cross-modal-review/SKILL.md) with these custom dimensions:

• VARIETY (fresh each chapter?)
• SPECIFICITY (real stories/dates/quotes?)
• DEPTH (new insight vs restating profile?)
• LEFT_COLUMN_FIDELITY (preserves the book?)
• EMOTIONAL_RANGE (joy as well as struggle?)

gbrain eval cross-modal --slug <slug>-personalized \
  --dimensions VARIETY,SPECIFICITY,DEPTH,LEFT_COLUMN_FIDELITY,EMOTIONAL_RANGE

Pass threshold: all dimensions average 7+ across models. If any dimension is below 6, rebuild with targeted fixes. The eval→fix→re-eval cycle is the quality multiplier. Evaluator model pairs and refusal routing follow conventions/cross-modal.yaml.

Children's book variant

For picture books and children's books (under ~5K words), use a Parent's Reading Guide format instead of the standard mirror:

• The Chapter half: what the book says on each page/spread.
• The Mirror half: written FOR THE PARENT reading aloud — what each page will feel like, what the child might ask at each age, what to say if they do, and what the book is really teaching underneath the simple words.
• Include: when to read it, how to handle specific reactions, and the book's deeper structure mapped to developmental psychology research.
• Tone: warm, practical, specific to the reader's children by name and age (from brain context).

Hand-assembled variants like this use the stacked-sections container.

4. Analysis: invoke gbrain book-mirror

gbrain book-mirror \
  --chapters-dir "$WORK/chapters" \
  --context-file "$CONTEXT" \
  --slug "$SLUG" \
  --title "Book Title Goes Here" \
  --author "Author Name" \
  --model claude-opus-4-7

The CLI:

• Validates inputs and loads chapter files.
• Prints a cost estimate (~$0.30/chapter at Opus) and prompts to confirm.
• Submits N child subagent jobs with read-only allowed_tools.
• Waits for every child to complete.
• Reads each child's job.result (the markdown analysis text).
• Assembles all chapters into one page with frontmatter + intro + per-chapter sections + closing.
• Writes ONE put_page to media/books/<slug>-personalized.md.
• Reports a JSON envelope on stdout: {"slug": "...", "chapters_total": N, "chapters_completed": N, "chapters_failed": 0}.

If any chapter failed, the CLI exits 1 and the user can re-run — idempotency keys (book-mirror:<slug>:ch-<N>) deduplicate completed chapters at the queue level, so retry is cheap. Note that reproducing verbatim book quotes plus the reader's verbatim words can occasionally trip a provider output filter; a chapter blocked that way is just a failed chapter — re-run, or retry with a different --model.

Model: Opus by default

The default model is claude-opus-4-7. Sonnet works (use --model claude-sonnet-4-6) but the mirror quality drops noticeably — the texture that makes the analysis feel like it was written by someone who knows the reader needs Opus-grade reasoning.

Cost gate

The CLI refuses to spend in a non-TTY context without --yes. CI / scripted invocations must pass --yes explicitly. TTY users get a [y/N] prompt before submission.

Deep retrieval raises total cost meaningfully versus a thin static context pack (roughly an order of magnitude at Opus rates). The quality jump is worth it for a book the reader cares about; use a static pack only for low-stakes runs.

5. PDF (optional)

After the brain page is written (the CLI already did the put_page), render to PDF using skills/brain-pdf:

# See skills/brain-pdf/SKILL.md for the invocation.

If the user asked for a deliverable, prefer the PDF over sending raw markdown — the brain page is the source of truth; the PDF is the artifact that travels.

6. Fact-check and cross-link

After the page lands, run a fact-check pass on factual claims about the reader (parents, siblings, marriage history, jobs, heritage). Common error patterns to look for:

• Conflating the reader's parents' relationship with patterns in extended family.
• Inventing backstory ("after his parents' divorce…") when the reader's parents are still together.
• Wrong number/age of children, wrong spouse / kid / sibling names.

If you can't verify a claim, remove it. Better to lose texture than to introduce a falsehood.

Cross-link entities mentioned in the analysis:

• For every person the mirror references with a brain page, add a back-link from people/<slug> to the new media/books/<slug>-personalized page (per conventions/quality.md Iron Law).

Quality bar (the bar)

The Chapter half should:

• Preserve the author's actual stories, statistics, frameworks, examples.
• Quote memorable phrases verbatim.
• Be detailed enough that the reader could skip the book and not lose much.

The Mirror half should:

• Use the reader's actual quoted words from the context pack.
• Reference specific dates, situations, people by name.
• Read like a smart friend who happens to know the reader's life deeply — pointing things out, not giving instructions.
• OBSERVE, never PRESCRIBE. The mirror holds up a reflection. The reader decides what to do about it. No directives, no action items, no "you should," no "consider whether," no rearranging of the reader's life.
• Frame connections as observations or gentle nudges: "This is the same pattern as…" or "Hard not to hear echoes of…" — NOT "You need to address this" or "Apply this framework to your Q3 planning."
• Be plain about direct hits ("This is exactly the [name a real situation]").
• Be honest about misses ("This chapter is less directly relevant because…"). Don't force connections.
• Resonant, not actionable. The mirror's job is recognition, not instruction. "That's exactly what we're doing" is the win. "Here's a 7-point plan to fix it" is overstepping.
• For team mirrors: Name team members for context ("this connects to what a teammate does"), NEVER for task assignment ("teammate: do X by Friday"). Don't invent organizational policies, veto chains, checklists, or structural decisions the team hasn't made. Only reference decisions that are in the team's actual documents. Frame everything else as questions or observations.

The whole document should feel like one coherent voice, calibrated to the reader's actual life rather than a generic profile, and honest about where the book's framing breaks down for this specific reader. It should make the reader feel SEEN, not studied — and work as good standalone writing even with every citation stripped.

Anti-patterns (do not do these)

• ❌ Skimming chapters. Standing instruction: preserve detail.
• ❌ Generic mirror. "This might apply if you've ever felt…" → kill on sight.
• ❌ Factual errors about the reader's life. Always fact-check after assembly.
• ❌ Giving the subagent put_page access. Trust contract is read-only; the CLI does the writing.
• ❌ Forcing connections. If a chapter doesn't apply, say so plainly.
• ❌ Sycophancy or moralizing in the mirror. No "you should…", no "consider…", no "perhaps it's time to…".
• ❌ Consultant mode. The mirror is not a strategy deck. No action items, no task assignments to named people, no invented policies or org structures, no "audit this quarterly," no numbered implementation checklists. The mirror OBSERVES and RESONATES. It's a friend at a bar saying "this part is so us" — not a consulting engagement. If the reader wants to turn an observation into a plan, that's their move. Not ours.
• ❌ Inventing rules the reader never said. Veto chains, editorial/ marketing separations, ombudsperson structures, campaign checklists — if the reader didn't establish it, the mirror can't declare it. Frame it as a question the author would ask ("who has the veto here?") or don't include it.
• ❌ Truncating the Chapter half. The book's actual content needs to survive. This is the #1 quality failure — rich chapter = varied mirror.
• ❌ Bare markdown pipe tables. They center-misalign uneven cells on GitHub and most renderers. HTML <table> with valign="top" on every <td>, or stacked sections. See the layout hard rule above.
• ❌ Repeating the same 5–6 themes across all chapters. Use the domain mapping and phrase caps from the quality system.
• ❌ Thin context pack. If the context pack is just USER.md bullets, the mirror will be generic. Invest in deep retrieval.
• ❌ Skipping the eval gate on high-stakes mirrors. At minimum, run a self-check: count mentions of key themes across chapters. If any theme appears in more than 3 chapters, fix before delivering.

Output checklist

• Book file exists locally (path known).
• Chapter texts under $WORK/chapters/*.txt with sane word counts.
• Context pack at $WORK/context.md is dense: deep-retrieval results grouped per chapter + domain map + phrase caps.
• gbrain book-mirror --chapters-dir … --context-file … --slug … --title … returned exit 0.
• media/books/<slug>-personalized.md exists in the brain.
• Layout check: no bare markdown pipe tables in the page.
• Anti-repetition self-check: no theme anchors more than 3 chapters.
• Fact-check pass complete (no errors against USER.md or other source-of-truth pages).
• Cross-links added from referenced people/companies.
• Optional: cross-modal eval gate passed (all dimensions 7+).
• Optional: PDF rendered via brain-pdf and delivered.

Related skills

• skills/brain-pdf/SKILL.md — render the personalized page to PDF.
• skills/strategic-reading/SKILL.md — read a book through a specific problem-lens instead of personalizing to the whole reader.
• skills/article-enrichment/SKILL.md — same shape applied to articles rather than books.
• skills/cross-modal-review/SKILL.md — the manual second-model quality gate; gbrain eval cross-modal is the scripted sibling surface.

Contract

This skill guarantees:

• Routing matches the canonical triggers in the frontmatter.
• Output written under the directories listed in writes_to: (when applicable).
• Conventions referenced (quality.md, brain-first.md, _brain-filing-rules.md) are followed.
• Privacy contract preserved: no real names, no fork-specific filesystem path literals, no upstream-fork references.

The full behavior contract is documented in the body sections above; this section exists for the conformance test.

Output Format

The skill's output shape is documented inline in the body sections above (see "Output", "Brain page format", or equivalent). The literal section header here exists for the conformance test (test/skills-conformance.test.ts).

When it fails

Follow the agent operator protocol for any gbrain error code, exit code, [AGENT] block or notice block. Specific to this skill:

• The CLI stops for cost confirmation (exit 3, or a non-TTY refusal without --yes): relay the per-chapter estimate and wait for the user's agreement before adding --yes.
• A paid run stops with no_pricing under a user cost cap: look up the model's per-token rate, tell the user, and after they agree ask the brain host's operator to run gbrain pricing set <model> --input <usd-per-1M> --output <usd-per-1M>; then retry.
• Exit 1 with chapters_failed > 0: the finished chapters are kept; re-run the same command to retry only the failed ones and tell the user how many chapters are still missing.

Anti-Patterns

The full anti-pattern list is in the body sections above; this header exists for the conformance test if the body uses a different casing.