Benchmark AI_TRUECOST_

real AI cost, not vanity metrics

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gpt-5.6-terra

Running gpt-5.6-terra inside devin.

FastAPI: Add POST /api/v1/projects/{project_id}/tasks endpoint Plan → Review plan → Execute → Review & fix → Open PR → Verify PR → Verify e2e

All steps run as one workflow, inside a single Docker container.

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5 of the 10 steps are agent sessions, each started fresh: only the repository working tree and the previous step's output carry over. Host steps orchestrate and verify, and cost nothing.
# Step Kind What happens
1 pullIssue host Fetches the GitHub issue and creates a branch
2 plan agent Drafts a plan from the ticket, including tests
3 reviewPlan agent Always runs; returns the full final plan
4 execute agent Implements the landing page; may run repeated preview captures; no harness step timeout
5 reviewAndCorrect agent Visual review against the brief and reference render; fixes layout and copy; no harness step timeout
6 openPullRequest agent Commits, pushes, opens a pull request into main
7 verifyPullRequest host Checks that the exact pull request is open
8 verifyPullRequestCheck host Waits for the required end-to-end check to pass
9 summarizeUsage host Totals tokens and cost
10 score host Records the final result
Speed
Reasoning
Run 1 2026-09-14 · standard · default $0.75 PASS

Steps

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Agent steps start a fresh session. Host steps are included in the run cost.
Step Status Cost Time In tok Out tok Tools
pullIssue succeeded $0.00 — 0 0 0
plan succeeded $0.15 0m 58s 24 4,122 34
reviewPlan succeeded $0.10 0m 54s 12 4,709 28
execute succeeded $0.22 1m 30s 45 6,991 42
reviewAndCorrect succeeded $0.13 0m 48s 30 3,035 34
openPullRequest succeeded $0.16 1m 02s 36 4,120 39
verifyPullRequest succeeded $0.00 0m 01s 0 0 0
verifyPullRequestCheck succeeded $0.00 0m 21s 0 0 0
summarizeUsage succeeded $0.00 — 0 0 0
score succeeded $0.00 — 0 0 0

Run totals

Cost
$0.75
Agent time
5m 12s
Input tokens
147
Output tokens
22,977
Cache-read tokens
1,000,105
Tool calls
177

Tool call mix

read
84
exec
43
find_file_by_name
20
todo_write
19
edit
7
grep
3
skill
1