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Carlos Scheidegger

@cscheid.net

the thing is I'm a scrub, and topped out at Fear 14 or so :(

January 12, 2026 at 1:59 PM

Carlos Scheidegger

@cscheid.net

> 33h -> 8h

What's really going to bake your noodle is to wonder what you can now do with those 25 hours, and what _that_ will enable, etc.

January 12, 2026 at 1:54 PM

Carlos Scheidegger

@cscheid.net

We're now actually running the thing through, and the best bug so far is that Claude Vision reads chords that say "F#7 Bm" and tells me that it's seeing a chord "V7", and then a chord "Bm". yes, "V7" as a string. This is too funny if you know what's up.

January 12, 2026 at 2:59 AM

Carlos Scheidegger

@cscheid.net

it's not really bespoke, it's pretty simple, and a music teacher taught it to me! Looks like this:

January 12, 2026 at 1:45 AM

Carlos Scheidegger

@cscheid.net

I have the smallest of all intersectional identities (since i pass as a white dude in the us right until i open my mouth), and what that first screenshot made me think of was the anecdote going around about the bear q followup, where some Black women choose the bear over white women.

January 11, 2026 at 9:10 PM

Carlos Scheidegger

@cscheid.net

I genuinely don't think we're ready for what this does to software engineering.

It's very cool and already absurdly useful. But boy can I think of many "monkey paw curls" scenarios!

January 11, 2026 at 9:08 PM

Carlos Scheidegger

@cscheid.net

Weird world, huh?

January 11, 2026 at 8:59 PM

Carlos Scheidegger

@cscheid.net

We're back, and Claude split my songbooks into ~300 pdfs for me, for a grand total of ~$5 in Anthropic credits. Now we're going to teach it to create the CSV files I ultimately want.

❯ We just finished extracting 300 tune PDFs to sheet-music/. Now, we will continue working on claude-notes/plans/2026-01-11-stage2-tonal-analysis-and-export.md . The
idea here is that we will send these PDFs to Claude Vision with the tooling in stage 1, and we need to write a followup program that will take that structured output,
perform some corrections, and then generate a CSV of the right format (which you can see in reference-exports/*.csv).

In order for you to understand how the CSV format is ultimately used, it might be worth it for you to analyze the source code of the React app we've built to render
these grids. You have that available in external-sources/automerge-music-grid. I mention this for two reasons.

1. we have so far not handled any tunes in 3/4 in automerge-music-grid, and you will see a number of them in your extraction. We need to decide what the CSV structure
will be. My idea is to continue using one beat per spreadsheet cell. In the 2/4 tunes we've had so far, we've attempted to fit 4 measures per CSV line in the parts. I
think we should stick to 4 measures per CSV line. However:

2. there are a few tunes which whose harmonic structure doesn't really fit this 4-measure-per-line strategy. You should make a note, explicitly, of two tunes that I
know will exhibit this phenomenon, so we can plan for how to denote them.

- The first tune is "Um Chorinho Pra Voce" by Severino Araujo, where you will find that part A has "two excess bars". The part is in Am, and has 18 bars instead of
16. The relevant part for this discussion is that:
- part A goes back to the tonic after 9 bars, and each "subpart" goes to the diatonic mediant C on bars 5 and 14. That means that in terms of creating the grid,
it's much nicer to have the lines start on the chords Am and C (splitting the part in lines of 4,5,4,5 measures respectively) than if we split them into 4 bars each,
where the excess bar would make each line shift.
- f…

January 11, 2026 at 8:35 PM

Carlos Scheidegger

@cscheid.net

It's going

Claude Code analyzing the choro songbook for tune boundaries. It says "Tune #3, Alma brasileira"

January 11, 2026 at 7:06 PM

Carlos Scheidegger

@cscheid.net

We've taken a detour to create a separate utility to split my big songbook PDF into smaller pieces:

The plan:

┌───────────────────┬──────────────────────────────────────────────────────┬────────────────────────────┐
│ Phase │ What │ Cost │
├───────────────────┼──────────────────────────────────────────────────────┼────────────────────────────┤
│ Phase 1: Analysis │ Vision API detects tune boundaries, generates │ ~$12.64 (632 pages × │
│ │ manifest │ $0.02) │
├───────────────────┼──────────────────────────────────────────────────────┼────────────────────────────┤
│ Phase 2: │ Python splits PDFs based on reviewed manifest │ Free │
│ Splitting │ │ │
└───────────────────┴──────────────────────────────────────────────────────┴────────────────────────────┘
Key insight: The title list gives us the names (in order), vision gives us the page boundaries. We match positionally and validate with fuzzy title matching.

Workflow:
Vol PDF → Vision analysis → Manifest JSON → Human review → Split → Individual PDFs

Open questions for you:

1. Front matter: Do the PDFs have intro pages (table of contents, preface) before the first tune? I need to know so I can skip them.
2. Multi-line OCR entries: I noticed lines 39-40 in vol-2-titles.md are split:
Este choro é o meu pranto Claudionor Cruz e
Pedro Caetano ..
2. Should I try to auto-detect these, or would you prefer to clean up the title files first?
3. Existing sheet-music/ files: You already have 5 PDFs there from earlier. Should I:
- Overwrite if regenerated?
- Skip existing files?
- Use a different output directory?
4. Run order: Should I do all 3 volumes at once (~$12.64), or one at a time so you can review the first manifest before spending more?

January 11, 2026 at 7:05 PM

Carlos Scheidegger

@cscheid.net

Now we're getting ready to convert this into the format I currently use in actual chord grid app.

Output files created:
output/
├── _extraction_summary.json
├── 01-01-a-ginga-do-mane.json
├── 01-02-aguenta-seu-fulgencio.json
├── 01-03-alma-brasileira.json
├── 01-04-alvorada.json
└── 01-05-amigo-bandolim.json

Would you like me to show you one of the other extracted JSONs for you to review? Or shall we proceed to the next step (refining prompts, or starting on Stage 2 tonal analysis)?

✻ Cogitated for 4m 5s

❯ Let's start on stage 2. Let's create a new plan document. In my current workflow, I have a set of
Google Spreadsheets with the music grids stored as values on a spreadsheet (plus conventions of how
parts are encoded). I want stage 2 to be a Python program that

- reads the information from the JSON object
- runs a Claude API session prompted to detect key change discrepancies
- then a script that converts the beat information into a CSV file that can be imported as a Google
Spreadsheet (we'll need to set up the Python google docs APIs accordingly, and I'll want some help
on the UI for that)

I have a number of CSV exports of actual music grids as CSV exports, alongside the sheet music you
would be importing from. We can use this both as a demonstration of the required format and as a
validation set for your own workflow. Do you think this would be a workable mechanism for arriving
at a stage 2 that, when combined with stage 1, produces a workflow that imports PDFs directly into
google sheets with the right format?

January 11, 2026 at 6:20 PM

Carlos Scheidegger

@cscheid.net

We're now at the point that Claude is refining its own instructions for extracting information from the sheet music:

⏺ Excellent results! The extraction cost ~$0.014 per page. Here's my analysis:

What worked well:
- Metadata extracted correctly (title, composer, tempo, time signature)
- Part markers identified (A at measure 5, B at measure 20)
- Chord symbols captured in reading order
- Navigation markers found (Segno, Coda, repeat signs, endings)

Issues to refine:
1. Beat positions missing - We need chords with measure AND beat location
2. Chord grouping - "Gm6, A7" should be two separate entries with positions
3. The "/" symbol - That's actually a slash indicating continuation, not a chord
4. Incomplete B section - Only first page, need page 2 for full picture

Let me run a second test with a more structured prompt that asks for JSON output with beat positions:

January 11, 2026 at 5:55 PM

Carlos Scheidegger

@cscheid.net

Now I'm admittedly playing with fire, but it's cute that this works (we're setting up API keys for the visual models. It previously told me to copy the key to the clipboard)

$⏺ Now edit the .env file to add your key: # Open in your editor open .env # Or use: nano .env, vim .env, code .env, etc. Replace PASTE_YOUR_KEY_HERE with your actual key (the sk-ant-api03-... value). Once you've saved the file, let me create a quick test script: ⏺ Write(test_api.py) ⎿ Wrote 28 lines to test_api.py """Quick test to verify Anthropic API key is working.""" from dotenv import load_dotenv load_dotenv() from anthropic import Anthropic def main(): client = Anthropic() … +18 lines (ctrl+o to expand) ❯ We're on a mac. I think you can use pbpaste. ⏺ Good idea! Let me grab it from your clipboard directly: ⏺ Bash(KEY=$(pbpaste) && echo "ANTHROPIC_API_KEY=$KEY" > .env && echo "Key written to .env (${#KEY} characters)") ⎿ Key written to .env (108 characters) ⏺ Key saved (108 chars looks correct). Now let's test it:$

January 11, 2026 at 5:46 PM

Carlos Scheidegger

@cscheid.net

Not disputing that, have you been to r/musictheory lol?

January 11, 2026 at 5:40 PM

Carlos Scheidegger

@cscheid.net

More back-and-forth before hitting "go"

❯ responding to your design document questions:

- **Fermatas**: May need a flag for held chords

Since we'll be using LLMs and your visual reasoning capabilities, we're going to need a prompt of some
sort, right? I ask because relatively few songs have fermatas and in my experience playing in rodas,
they're not so important to record. (my current music grids all lack them, for example). So I would
like the LLM part of this pipeline to be able to flag fermatas when it sees them, but not have the
output representation store them just yet (we'll do it if we find there's enough of them)

The same thing goes for tempo changes and dynamics: I'd like the LLM parts of the pipeline to report
any unusual findings (maybe even in a natural language field so that you can inspect your own findings
in the future)

slash notation duration: Slash notation *is* important, and should be captured as is. The slash chords
in this set of sheet mostly music denote inversions (but not all of them). Nevertheless, the difference
between a regular inversion notated as slash and a "real" slash chord (like a G/C) is not important
for the purposes of this app. I trust the denoted chord in these sheets well enough to let them through
as is, and I'll fix whatever issues happen at the later UI stage

January 11, 2026 at 5:34 PM

Carlos Scheidegger

@cscheid.net

This is cute, and makes me estimate Opus 4.5 to be at the > 90% percentile of music theory knowledge in r/musictheory posters:

Regarding question 3: Yes, I can distinguish C major from A minor based on chord progressions. In choro especially, the tonic is usually clear from:
- Where phrases resolve (the "home" chord)
- Dominant-tonic relationships (G7→C vs E7→Am)
- Section endings

So we'll store the implied tonic (e.g., "Dm" not "1 flat").

January 11, 2026 at 5:16 PM

Carlos Scheidegger

@cscheid.net

More questions, more responses of mine. I think people tend to be surprised by the length of planning discussions, so I'm trying to show the "nuts and bolts" of a real CC session here.

$Transcript (including some stuff missed in the screenshot) Open Questions for You: ... Would you like to iterate on the schema design, or shall we proceed to implementing the foundation (Pydantic models, PDF conversion, CLI skeleton)? ✻ Worked for 2m 39s ❯ 1. Some tunes have a small anacrusis, and some tunes have a longer intro. For the purposes of this project, let's consider the distinction between intro and pickup bars to be a distinction in engraving rather than a distinction in the structure of the music. So for the structured representation, let's use "intro" as the general term. (You probably want to write these decisions into a "claude-notes/designs/output-representation.md" file or similar. Please do that) 2. Sub-beat precision: Let's attempt to extract this as _fractions_ instead of real numbers (since then we don't have to worry about 2.3 vs 2.33, etc when it's likely that what you meant was a 1/3 beat offset into the 3rd beat, or 7/3). I think it will be easier for you to not make arithmetic mistakes by us creating a representation that always has an integer beat, and might have a fractional sub-beat offset. Something like '{ location: {beat: 1} }', but '{ location: { beat: 2, offset: '1/3' } }'. 3. Key representation: Do you think your AI capabilities can distinguish between recognizing a key of C and key of Am from the tonal properties of the chord structure? If so, then let's store the key representation as the implied 1 chord ('C' vs 'Am'). Otherwise, let's not store keys at all. 4. Coda/Segno: Let's try to store the marker positions (though that will also require our representation to know about which measure ranges represents which ends of which parts) Ultrathink.$

January 11, 2026 at 5:14 PM

Carlos Scheidegger

@cscheid.net

From here, it presented a plan and asked me questions. You can see some of my answers as I'm typing them (right now, in fact)

CC transcript (including a part that was clipped from the screenshot)

Open questions for you:

1. Do you have a preference for which AI API to use (Claude, OpenAI, or local)?
2. Is there a cost budget consideration for processing 300 files?
3. How accurate does the chord extraction need to be? (Perfect, or acceptable with some manual fixes?)
4. Would you like a review/correction UI, or is JSON output sufficient?

Would you like to iterate on any aspect of this plan before we proceed?

✻ Baked for 2m 25s

───────────────────────────────────────────────────────────────────────────────────────────────────────────
❯ > 1. Do you have a preference for which AI API to use (Claude, OpenAI, or local)?

I strongly prefer Claude. We're on a max plan here and we should use that if available, but I am
willing to spend credits if the functionality you need is only behind token-based pricing. I will need
some help setting up those APIs for Python, though.

> 2. Is there a cost budget consideration for processing 300 files?

What's your estimate for cost per document

> 3. How accurate does the chord extraction need to be? (Perfect, or acceptable with some manual
fixes?)

Manual fixes are acceptable if the baseline is sufficiently good (I don't know what I mean by
sufficiently, but this app is kind of the experiment I'm doing to see if the quality we get is
"sufficient")

> 4. Would you like a review/correction UI, or is JSON output sufficient?

A review/correction UI would be excellent on for a second phase, especially since both UI and CLI
factor nicely through the JSON representation. So maybe what this means is that we should first define
the JSON output well enough that we can split up the work on the abstraction boundary of the output
representation.

January 11, 2026 at 4:56 PM

Carlos Scheidegger

@cscheid.net

skipping a bit now to get to the end of this response:

⏺ Now let me create the CLAUDE.md file with comprehensive project information.

⏺ Write(CLAUDE.md)
⎿ Wrote 106 lines to CLAUDE.md
# PDF to Music Grid Importer
## Project Overview
This is a command-line application for converting scanned choro sheet music PDFs to structured
JSON representations. The target is approximately 300 pieces of sheet music with consistent
engraving conventions.
## Development Environment
- **Python package manager**: uv
- **Python version**: 3.13+
… +96 lines (ctrl+o to expand)

⏺ Now let me create the initial overall plan document.

⏺ Write(claude-notes/plans/2026-01-11-overall-architecture.md)
⎿ Wrote 153 lines to claude-notes/plans/2026-01-11-overall-architecture.md
# Overall Architecture Plan
**Created**: 2026-01-11
**Status**: Draft - awaiting review
## Goal
Build a CLI tool that converts ~300 scanned choro sheet music PDFs into structured JSON
representations capturing chord progressions, part structure, and form.
## Approach Options
… +143 lines (ctrl+o to expand)

⏺ I've set up the project scaffolding. Here's what was created:

January 11, 2026 at 4:50 PM

Carlos Scheidegger

@cscheid.net

Its response:

Claude Code transcript:

⏺ I'll help you set up this project for converting sheet music PDFs to structured music grids. Let me start by exploring what's already in place and understanding the sheet music files you have.

⏺ Bash(ls -la)
⎿ total 16
drwxr-xr-x 5 cscheid staff 160 Jan 11 10:14 .
drwxr-xr-x 80 cscheid staff 2560 Jan 11 10:04 ..
… +3 lines (ctrl+o to expand)

⏺ Bash(ls -la sheet-music/ 2>/dev/null || echo "Directory not found")
⎿ total 10768
drwxr-xr-x 7 cscheid staff 224 Jan 11 10:20 .
drwxr-xr-x 5 cscheid staff 160 Jan 11 10:14 ..
… +5 lines (ctrl+o to expand)

⏺ Let me examine one of the PDFs to understand the sheet music format better.

⏺ Read(sheet-music/01-01-a-ginga-do-mane.pdf)
⎿ Read PDF (544.5KB)

⏺ Excellent! This is choro music - Brazilian instrumental music. I can see the structure clearly:
- Parts labeled A, B, C in boxes
- Chord symbols below the bass clef (Gm6, A7, Dm, Em7(b5), etc.)
- 2/4 time signature
- Repeat signs with 1st/2nd endings
- Navigation symbols (Segno 𝄋, Coda ⊕, D.S. al Coda)
- Key signature changes between sections

Let me look at another PDF to confirm the patterns are consistent, then I'll set up the project.

January 11, 2026 at 4:49 PM

Carlos Scheidegger

@cscheid.net

In a fresh git repo, I start with a 2-4 para description of what I want.

A request to Claude Code:

I want to create a command-line application for converting scans of sheet music to music grids. The
scans I have all follow the same engraving conventions. They have a treble and bass clef and chord
music symbols throughout. The tunes in the genre of music that's transcribed there tend to have a
fairly rigid form with a fixed number of parts that are repeated in a semi-regular (the same way
that a rondo is sometimes played ABACA, sometimes ABACBA, etc). I want an app to convert a PDF in
these forms to a structured representation of each part (like a JSON object), together with a
representation of where each chord symbol lies in terms of the number of beats from the beginning of
the part. For the purposes of this app, the tunes in this genre are written in either 2/4 or 3/4.

I have about 300 such pieces of sheet music in PDF format to convert; I've added the first five of
them to the sheet-music/ directory.

We will be building this app over a number of sessions, and so I want to start with setting up
CLAUDE.md for this project. I don't care what tools we use to build this; I expect the Python
ecosystem to be adequate for this. You have a recent version of uv in your path, and I would like us
to use it to set up a self-contained development environment for the project. I also want us to use
written markdown plans to coordinate and record the development. For this, please create a
'claude-notes/plans' directory, and add to CLAUDE.md that all plans we work on should be written to
'claude-notes/plans/YYYY-MM-DD-<description>.md'.

Please set up the project scaffolding as above, an overall summary plan, and then let's iterate on
that plan. Ultrathink.

January 11, 2026 at 4:48 PM

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