204 Runs, 100M Tokens: Which Agent Can Keep a Knowledge Base?

30 models & 13 harnesses put to the test · Jul–Oct 2026

For some years I have used an Obsidian vault as my knowledge base: insights, decisions, people, tasks, ideas. Can an agent keep it up to date? I recorded a real meeting (the other participant agreed beforehand to the recording and the AI processing) and let agents update my vault, putting the right insights in the right files and folders.

Vault
~200 files, ~15K lines
Transcript
46 min of ambiguous, garbled French speech-to-text, ~30K tokens
Instructions
a one-line prompt, but a 145-line vault guide and a skill to file the insights
Context
agents search the vault, working context 50–95K tokens
Expected
4 destinations: a Journal entry, a meeting note, idea notes, a contact profile: right folder, frontmatter, tags, links
Score
out of 100: half note quality, half judgment, minus penalties (details)

Verdict: local works, if you give it time

Some frontier cloud models get it right in 1–6 minutes, but many other cloud models fall short. Locally, only one setup gets it right reliably, in about 15 minutes: the plain Qwen3.8 27B, 4-bit, extra-high effort, on Pi. Fine-tunes hit the top once, then fall back.

    Why it's a difficult bench

    What I would use today

    OptionConfigurationScoresTimeCost/run
    Cloud: when privacy allows
    Best qualityClaude Opus 5.5 on Pi, or GPT-6.1 Sol at medium effort. One run each.992–5.5 min$0.25–0.86
    Best valueGPT-6 Luna, max effort. Any harness.80–971–6 min~$0.04
    Local: when it must stay private
    UseQwen3.8 27B, plain model, 4-bit, extra-high effort, 65K output limit, on Pi86–9714–19 min$0
    Runner-upSwift, a Qwen3.8 27B fine-tune, same setup. Faster, less steady.40–939–11 min$0

    Every model, ranked

    One run proves little. The same Swift setup scored 93, 93, 57, 40, then 92. Models are ranked by their median run, with the worst run beside it.

    Median · Worst

    The middle and the lowest score of a model's runs. Q · J = median quality and judgment, out of 50 each.

    Harness

    The agent program that drives the model. Pi and OpenCode were used most; Pi + custom prompt: Pi with my own system prompt.

    Where it ran

    Self-hosted: my laptop or home server. Splash is a faster inference runtime on the same home server. Cloud: a provider's API.

    Runs counted

    PiOpenCode 1OpenCode 2other harness

    Gaps under about 20 points are noise. Quantization and packaging variants are merged into one row; fine-tuned derivatives keep their own. Gray edge: cloud. Green edge: my local pick.

    Score, cost and speed

    One dot per model: its median run. Up is better, left is cheaper. Self-hosted models have no per-run bill and sit in the $0 column. Color shows how long the run took, from green (fast) to red (slow).

    Logarithmic cost axis. Cost is what the provider reported for the run; cloud runs without a reported cost are left out. Only the top models are named; hover any dot for its details.


    Other learnings

    Harnesses do matter

    The harness is the program around the model: its prompt, tools and limits. It decides whether a run finishes, and the same model can score 30 points apart on two harnesses. Which harness works best depends on the model.

    No harness wins everywhere. Pi was best for Claude Sonnet 5.5 and the self-hosted models, OpenCode 2 for Qwen3.8 Flash Next; GPT-6 Luna and DeepSeek did well on all of them. The other harnesses mostly stalled or failed their tool checks.

    Thinking effort matters

    For self-hosted models, more than anything else. The same model, server and harness, at two effort levels:

    Score in detail

    The agent had to read the meeting transcript and update the vault. A grader then checked every file it wrote, item by item:

    PartWhat was checkedPoints
    Quality of the notes: 50
    Right filesFour outputs, each in the right folder with real content: a Journal entry, a meeting note, an insight note (one idea per note), a profile of the other participant15
    Main contentThe framework the other participant explained during the call. Points for each of its ideas captured accurately.20
    House styleThe vault guide's conventions: frontmatter, dated file names, links to existing notes, a takeaway and a "so what" in the insight, no text copied across notes10
    ExtrasConnecting anecdotes to notes already in the vault, and listing concrete next steps5
    Judgment: 50
    Who does whatThree follow-ups agreed in the call, each with the right sender: the participant sends me a short profile to forward to one of my contacts (12); I help with an introduction (5); I send them an article (3)20
    RelationshipDescribes the participant as a peer and connector10
    BiographyThe participant's background, not mine: right past employers and current independent work, no invented roles (9); right family origin (6)15
    RestraintLeaves the vault's reference files about me untouched5
    Penalties
    History lostErasing existing content such as the Journal's past entries (−10 for a single line)−40
    Invented biographyA false professional identity for the participant (−10 if isolated)−20

    A score can go below zero. A hand-written reference answer scores 100.

    How the runs were launched and graded, and the problems met · all 204 runs (CSV)

    About me: I work in AI transformation by day, at a large corporation. At night I write and run experiments like this one. More on my Substack, The Intelligence Fabric.