Overcast event bisect

Skill kdr/overcast/skills/overcast-event-bisect

Localize the exact instant of a one-way state change (light on, door opens, poster removed) by binary-searching frames — ~log2(N) VLM calls.From its SKILL.md

Install

npx -y skills add kdr/overcast --skill overcast-event-bisect

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

2 things to look at

12 stars12 stars. Stars are a popularity signal and not a quality one, but at this level it is likely that nobody has read this closely except its author, and you would be relying on your own review.
runs commandsInstructs the agent to run 8 commands, including `overcast doctor --json` and 7 more.

SKILL.md

2.4 KB, 598 tokens by cl100k_base, as published. Nobody here has run it

overcast-event-bisect

Use this skill when a video contains a single MONOTONE transition — a condition that is false before some instant and true after it (or vice versa), and does not flip back. Binary search finds it in about log2(window/precision) vision calls (~12 calls localizes to ~1s inside an hour). Use the broad overcast skill and overcast/reference/verbs.md for exact flags.

Workflow

Local clip + record id (see frame:// needs media on disk):

overcast doctor --json
overcast case init --json
overcast watch ./clip.mp4 --json        # -> record id REC (also gives shot context)

Confirm the transition is bracketed AND monotone — the two endpoints must disagree on the predicate:

overcast see frame://REC@<lo> --prompt "Is <predicate> true? answer only yes or no" --json
overcast see frame://REC@<hi> --prompt "Is <predicate> true? answer only yes or no" --json

If both give the same answer, the flip isn't in [lo,hi]. If the predicate toggles more than once, it isn't monotone — use overcast-pinpoint instead.

Bisect: test the midpoint, keep the half that still straddles the flip, repeat until hi - lo is within your precision:

overcast see frame://REC@<mid> --prompt "Is <predicate> true? answer only yes or no" --json
# keep the straddling half: if mid's answer == lo's answer, set lo=mid; else hi=mid
# (correct whichever way it flips — false->true OR true->false)

Report the transition window and show it:

overcast note "<predicate> flips" --ref REC --at <lo-hi> --confidence high --json
overcast view REC --at <lo-hi> --json
overcast brief --export ./transition.md --json

Output

The converged [lo, hi] bracket — the two adjacent see frames that straddle the flip (their record.ids + media.at) — and the call count. That bracket IS the answer window — don't over-claim a single frame.

Caveats

Bisection is only valid for a one-way change; a light that blinks or a person who comes and goes will mislead it — verify monotonicity at step 2, and fall back to overcast-pinpoint (peak search) or overcast-presence-window for recurring or interval events. Needs the video local.

What ships with it

Read from the repository

Just SKILL.md. No reference files, no scripts.

Gives 0 of the 12 instructions most root cause skills give in 598 tokens

Counted across 120 of the 151 authors here whose files we hold, read 2026-09-06

Add stack trace instrumentation when manual tracing failsin 8 of 120, across 5 files
Trace backward through the call chainin 8 of 120, across 5 files
Use console.error in tests instead of loggerin 8 of 120, across 5 files
Capture the full call chain with new Error().stackin 8 of 120, across 5 files
Fix the root cause, not the symptomin 7 of 120
Log before the dangerous operation, not after it failsin 7 of 120, across 4 files
Log directory, cwd, environment variables, and stackin 7 of 120, across 4 files
Add validation at each layer as defense-in-depthin 6 of 120, across 3 files
Run tests and grep for the debug outputin 6 of 120, across 3 files
Analyze stack traces for test file names and line numbersin 6 of 120, across 3 files
Fix at the source, not the symptomin 5 of 120, across 2 files
Assign every action item an ownerin 5 of 120

Said here and by no other author read

Copy the video clip locally
Watch the clip to get a record id
Query both endpoints with a yes-or-no predicate prompt
Verify the predicate flips only once
Test the midpoint each iteration
Keep the half that straddles the flip

Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once. Length counted with cl100k_base; the agent that loads this file may tokenize it differently.