Look-Back Effort Accounting (public draft)

Measure a completed git range or finished run. This is a retrospective

activity-volume model: it estimates how much implementation work the delivered

change represents under a consistent set of coefficients.

It does not measure business value, code quality, developer worth, dollars

saved, or what a team “should” have taken. Lines changed are a size proxy, not

an outcome.

Credit and adaptation

This draft descends from

Todd Saunders’s public `/cost-estimate` prompt:

lines of code plus complexity translated into senior-developer hours. I first

used it publicly on March 5, 2026 with both hours and dollar

return-on-investment framing.

This version changes the purpose and mechanics:

• retrospective activity accounting rather than replacement-cost valuation;
• hours only, with no dollar or return-on-investment claim;
• a small five-tier file model;
• deletions reported as separate cleanup credit;
• attended wall-clock kept separate from summed agent labor;
• anonymized ledger rows feeding a separate forward-estimation draft.

The current fork retires the dollar layer and keeps the hours-only accounting

skeleton. Julien Barbier’s later open-source

`/cost-estimate` is a

parallel expansion of Todd’s idea, not the direct parent of this fork. The

adaptations and any mistakes here are mine.

Inputs

Collect:

1. a closed git range;
2. per-file insertions and deletions with rename detection;
3. session start and verified finish;
4. summed worker durations, if the harness exposes them;
5. completed task count and task types;
6. exclusions for generated, vendored, lock, snapshot, and minified files.

Do not publish repository names, branches, home paths, emails, account names,

customer data, or raw agent transcripts.

Real coefficients used by this draft

These are the current coefficients from one personal workflow. They are knobs,

not validated industry constants.

Deletion-only cleanup is credited separately at 120 deleted lines/hour.

For the companion forward forecast, the current anonymized trace calibration

uses an overall human-equivalent → attended-agent coefficient of 43.3× for

the window 2026-06-17 through 2026-07-14. Do not apply that coefficient to

someone else’s workflow without collecting local actuals.

File classification

Use the file’s responsibility, not merely its extension.

When uncertain, round up one tier and record the judgment.

Calculation

For each included file:

creation_h = inserted_lines / tier_rate

Across the range:

human_equivalent_h = Σ creation_h
cleanup_credit_h = total_included_deletions / 120
attended_wall_h = verified_finish - attended_start
agent_labor_h = Σ worker durations  # only when measured

Keep all four values separate. In particular, do not blend cleanup credit into

the insertion-derived headline and do not call summed parallel labor

“wall-clock.”

Optional descriptive ratios:

attended_multiplier = human_equivalent_h / attended_wall_h
labor_multiplier = human_equivalent_h / agent_labor_h

These ratios are diagnostics for the observed run. They are not general claims

about agent productivity.

Required output

## Look-back: [anonymized run description]

Range: [start]..[end]
Tasks completed: N
Commits: N | +X inserted | -Y deleted | Z files

| Tier | Files | Insertions | Rate | Human-eq h |
|------|------:|-----------:|-----:|-----------:|
| T1 | ... | ... | 60 | ... |
| ... | ... | ... | ... | ... |
| **Total** | **N** | **X** | | **H.H** |

Cleanup credit: D / 120 = C.C h (reported separately)
Attended wall-clock: W.W h (measured | reconstructed | assumed)
Agent labor: A.A h (measured | unavailable)

Interpretation: activity-volume proxy only; not value, quality, savings, or a
universal speed claim.

Ledger row

Append an anonymized row to a private ledger:

{
  "id": "anon-001",
  "work_type": "chore",
  "tasks_completed": 4,
  "insertions": 1100,
  "deletions": 40,
  "human_equivalent_h": 36.2,
  "cleanup_credit_h": 0.33,
  "attended_wall_h": 0.42,
  "agent_labor_h": 0.90,
  "walltime_source": "measured",
  "rates_version": "personal-v1"
}

The public artifact may contain rounded aggregates. The private ledger should

retain enough provenance to recompute the result.

Guardrails

• Exclude generated and vendored material, but retain an auditable exclusion

count.

• Use rename-aware git statistics so moves are not counted twice.
• Do not infer active human attention from the first and last commit alone.
• Record failed attempts and rework when the trace supports it.
• Treat zero-line work items as missing size data, not zero effort.
• Label reconstructed or assumed clocks; do not present them as measured.
• Keep forecasting in the companion forward skill so hindsight does not leak

into a supposedly prospective estimate.

• Revisit the coefficients as the model, harness, repository, and working style

change.

Closing the loop

Compare the completed result with the forecast recorded before execution:

schedule_error = actual_attended_wall_h / forecast_schedule_wall_h
labor_error = actual_agent_labor_h / forecast_agent_labor_h
human_eq_error = actual_human_equivalent_h / forecast_human_equivalent_h

Keep the misses. A calibration that remembers only favorable runs is a story,

not an estimate.

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*Portable draft · real coefficients from one anonymized personal workflow ·

retrospective activity accounting, not valuation*