antigravity cli/gemini-3.8-flash-high

* f266fb6  (10 minutes)  <Riza Fahmi>   Complete S7: handle terminal Ctrl-C with partial summary and exit 130
* a3d65e9  (19 minutes)  <Riza Fahmi>   Complete S6: report elapsed time and latency percentiles
* 3d122a2  (22 minutes)  <Riza Fahmi>   Complete S5: report HTTP outcomes and exit codes
* ebafcbc  (25 minutes)  <Riza Fahmi>   Complete S4: paced 5-second loop with rate limiting and timeout cancellation
* 55c2577  (29 minutes)  <Riza Fahmi>   Complete S3: send bounded GET with streaming, TLS verification, and 2s timeout
* 5b9b145  (36 minutes)  <Riza Fahmi>   Complete S2: validate CLI arguments with exit code 2 on errors
* 911df8a  (38 minutes)  <Riza Fahmi>   Complete S1: launch CLI with help and resolved entry point

1. 1Busy-Polling Background Tasks Burnt ~31% of Total Cost ($1.68)4 points▸

   • Whenever a run_command call exceeded the 10-second synchronous wait cap (WaitMsBeforeAsync: 10000), the harness backgrounded it (24 times total) and automatically emitted a system_message wakeup when the command finished.
   • Instead of ending its turn and waiting for that system_message, the agent polled manage_task(Action: "status") 99 times (plus 6 kill calls = 105 manage_task calls, or 27.1% of all 388 LLM turns) every ~3.5 seconds.
   • During the final mix test runs in S7 and Post-S7 (which took 102.1s and 101.9s at steps 671 and 738), the agent polled manage_task 24 times and 22 times in a row while context was at its peak (~250k–268k tokens).
   • Impact: Those 105 manage_task turns alone consumed 19.44M cached tokens and 253k uncached input tokens, costing $1.68 (30.9% of the entire $5.43 run). Stopping and waiting for the reactive system_message would have cut LLM calls from 388 to ~283 and saved ~$1.68.
2. 2Erlang/Elixir SIGINT (Ctrl-C) Handling Dominated Complexity (47% of Calls)4 points▸

   • S1 + S7 accounted for 183 of 388 LLM calls (47.2%) and 52.5% of all thinking tokens (36,341 / 69,199).
   • Why: In S1 (steps 28–123), the agent tried calling :os.set_signal(:sigint, :handle) and System.trap_signal(:sigint, ...) and hit BEAM's built-in restriction: Erlang's signal server intercepts SIGINT for the interactive BREAK menu and Elixir's System.trap_signal/3 explicitly disallows :sigint via guard clauses.
   • Four of the agent's 5 search_web calls were spent researching BEAM/escript SIGINT handling before it arrived at the working architecture in cb: a POSIX shell wrapper that traps INT, runs escript with +Bi (disabling the BEAM break handler), and forwards SIGTERM to the BEAM process so System.trap_signal(:sigterm, ...) can cleanly stop the benchmark loop.
   • While prototyping this with erl -help and Python pty.openpty() scripts (steps 38, 65, 73, 111, 596, 605), 6 commands hung waiting on terminal I/O and had to be killed after 10–23s.
3. 3Context Caching Saved 87% on Input Cost ($36.72 Saved)3 points▸

   • 98.11% cache hit ratio Out of 55,453,077 total prompt tokens sent across the 388 turns, 54,406,484 were served from cache (cache_read_tokens).
   • Zero mid-run cache invalidations: Only 7 steps had cache_read_tokens: 0—all within the first 15 steps (1, 3, 5, 7, 9, 13, 15) while the initial prompt was warming up. All 381 subsequent LLM calls achieved a cache hit.
   • Dollar impact: Without implicit caching, 55.45M input tokens at $0.75/1M would have cost $41.59 (total run $42.16). Caching reduced input cost to $4.87 ($0.78 uncached + $4.08 cached), saving $36.72 (82% of total cost).
4. 4Compounding Effect: Sequential 5s Integration Tests × 268k Context Window4 points▸

   • Context grew steadily from 10,704 tokens (step 1) to 268,770 tokens (step 796), spending the last 112 LLM calls above 200k tokens.
   • At the same time, because each slice added real-time CLI integration tests (5-second benchmark loops and 2-second timeouts), mix test wall-clock time grew from 0.75s (S1) → 12.7s (S3) → 27.5s (S4) → 51.4s (S5) → 102.1s (S7).
   • Running full mix test suites late in the conversation when context was ~250k+ tokens—combined with the 10s backgrounding threshold—caused the final verification (Post-S7, just 2 test runs) to cost $0.74, more than S2 ($0.20), S4 ($0.52), S5 ($0.59), or S6 ($0.38).
   • Takeaway for test design: Running targeted unit/simulated-clock tests during iteration and reserving full 5-second real-clock CLI suite runs (mix test --only integration) for final checks keeps mix test under the 10s threshold and avoids background-polling spirals.
5. 5High Edit Precision (99.2% Tool Success Rate)4 points▸

   • Out of 387 tool calls, only 3 returned tool errors (0.78% error rate):
   • Step 156: write_file failed once because test/capy_bench_test.exs already existed (Overwrite: true was omitted).
   • Steps 539 & 545: edit_file failed twice on target string mismatches in test/cb_timing_test.exs during S6 and immediately self-corrected.
   • All mix credo and Elixir 1.20 type-checking warnings (steps 191, 247, 343, 359) were caught and fixed before each slice's commit.