{
 "measurement": "Claude Code's own startup floor on 2.1.251, with and without tool search",
 "delta_series": {
  "what": "Every published floor corpus on this site, oldest first, read from the files rather than typed, so the 'how long has this been steady' claim is checkable here.",
  "releases": [
   {
    "version": "2.1.229",
    "tool_search_delta": 17804,
    "floor_tool_search_on": 22340,
    "floor_tool_search_off": 40144
   },
   {
    "version": "2.1.231",
    "tool_search_delta": 17805,
    "floor_tool_search_on": 22404,
    "floor_tool_search_off": 40209
   },
   {
    "version": "2.1.232",
    "tool_search_delta": 17664,
    "floor_tool_search_on": 22528,
    "floor_tool_search_off": 40192
   },
   {
    "version": "2.1.233",
    "tool_search_delta": 14644,
    "floor_tool_search_on": 22297,
    "floor_tool_search_off": 36941
   },
   {
    "version": "2.1.236",
    "tool_search_delta": 15069,
    "floor_tool_search_on": 22787,
    "floor_tool_search_off": 37856
   },
   {
    "version": "2.1.238",
    "tool_search_delta": 15069,
    "floor_tool_search_on": 22787,
    "floor_tool_search_off": 37856
   },
   {
    "version": "2.1.241",
    "tool_search_delta": 15069,
    "floor_tool_search_on": 22793,
    "floor_tool_search_off": 37862
   },
   {
    "version": "2.1.243",
    "tool_search_delta": 15251,
    "floor_tool_search_on": 22959,
    "floor_tool_search_off": 38210
   },
   {
    "version": "2.1.246",
    "tool_search_delta": 15069,
    "floor_tool_search_on": 22801,
    "floor_tool_search_off": 37870
   },
   {
    "version": "2.1.251",
    "tool_search_delta": 15193,
    "floor_tool_search_on": 17207,
    "floor_tool_search_off": 32400
   }
  ],
  "consecutive_prior_releases_at_the_previous_delta": 1,
  "delta_moved_this_release": true
 },
 "claude_code_version": "2.1.251",
 "claude_code_version_recorded_at_runtime": "2.1.251 (Claude Code)",
 "supersedes": "baseline-floor-2-1-246.json. The installed release moved 2.1.246 -> 2.1.251, and /cost/ quotes these figures, so a stamp that has not been re-measured is the calculator quoting a version nobody runs.",
 "why": "Every figure on /cost/ is quoted against a version. When the installed release moves, a stamp that has not been re-measured is the tool quoting a version nobody is running.",
 "method": {
  "floor": "An EMPTY temp directory, created fresh per measurement and asserted empty, with --setting-sources project asserted onto the command line so nothing user-scope loads. Prompt: 'Reply with only: OK'.",
  "tool_search_off": "The same floor with ENABLE_TOOL_SEARCH=false in the child environment, asserted present only on that arm.",
  "loaded": "The same prompt with --setting-sources asserted ABSENT, so the arms cannot silently be the same measurement.",
  "tokens": "inputTokens + cacheCreationInputTokens + cacheReadInputTokens from modelUsage. .usage recorded alongside because the published measure-context.sh reads it.",
  "estimator": "MODE over every repetition of a cell, carried forward unchanged from the 2.1.231 corpus. modelUsage on this call is bimodal, so the MINIMUM picks the rare run where an intermittent call did not fire and publishes a floor several hundred tokens low. The harness prints per-round minima to the console; those are NOT what is published here.",
  "population": "Every repetition: two per round across all rounds, pooled. Not per-round minima.",
  "controls": {
   "noise_floor": "Every cell measured TWICE per round, the gap kept as that round's noise and published per round.",
   "same_round": "All arms run inside one round before the next begins.",
   "flag_both_ways": "--setting-sources project asserted PRESENT on the floor arms and ABSENT on the loaded arm; ENABLE_TOOL_SEARCH asserted present only on the off arm.",
   "arrival": "Every reply had to be exactly OK.",
   "version_recorded": "The harness now reads `claude --version` at start and writes it into the output. Not having that is why a corpus measured the day before cannot be pinned to a release."
  }
 },
 "results": {
  "floor_tool_search_on": 17207,
  "floor_tool_search_on_repetitions": "16 of 16",
  "floor_tool_search_off": 32400,
  "floor_tool_search_off_repetitions": "16 of 16",
  "tool_search_delta": 15193,
  "change_since_2_1_246": {
   "floor_tool_search_on": "22,801 -> 17,207 (-5,594)",
   "floor_tool_search_off": "37,870 -> 32,400 (-5,470)",
   "tool_search_delta": "15,069 -> 15,193 (+124)",
   "loaded_machine_total": "64,083 -> 63,369 (-714)"
  },
  "distributions": {
   "floor_ts_on": {
    "mode": 17207,
    "count": 16,
    "n": 16,
    "tie": false,
    "distinct": [
     17207
    ],
    "histogram": {
     "17207": 16
    }
   },
   "floor_ts_off": {
    "mode": 32400,
    "count": 16,
    "n": 16,
    "tie": false,
    "distinct": [
     32400
    ],
    "histogram": {
     "32400": 16
    }
   },
   "loaded": {
    "mode": 63369,
    "count": 8,
    "n": 10,
    "tie": false,
    "distinct": [
     63369,
     63648
    ],
    "histogram": {
     "63369": 8,
     "63648": 2
    }
   }
  },
  "dot_usage_modes": {
   "floor_ts_on": 16310,
   "floor_ts_off": 31503,
   "loaded": 63369
  },
  "loaded_machine_total": 63369,
  "loaded_repetitions": "8 of 10"
 },
 "known_limits": {
  "one_machine": "One machine, one account. The floor arms exclude user-scope config by design; the loaded arm is this machine's configuration and transfers to nobody. CARRIED FORWARD unchanged.",
  "bimodal_modelusage": "GENERATED from this run's own histogram, not typed. Earlier corpora on this site carried a hand-written sentence here describing the previous version's distribution, which would have been republished unchanged and unchecked. On 2.1.251 floor_ts_on returned 1 distinct value(s) (16 of 16 at the mode) and floor_ts_off returned 1 (16 of 16). Both arms were single-valued, so the 198- and 521-token intermittent components that dominated noise on this site for weeks did not appear. The MODE estimator is kept regardless, because one clean version is not evidence they are gone for good, and results.distributions publishes the histogram so a reader can check.",
  "loaded_arm_also_moved": "CARRIED FORWARD. The loaded arm mixes the version change with any change to this machine's user-scope configuration, and the two are not separated here.",
  "INDEPENDENT REPLICATION, AND WHY IT IS NOT POOLED": "A separate 4-round invocation run minutes earlier returned floor_ts_on 17,205 and floor_ts_off 32,398, single-valued across all its repetitions, with a tool-search delta of 15,193 IDENTICAL to the published run. It is reported rather than pooled because its base directory name is one character shorter, and this site has measured that the startup floor moves with the working-directory path. Pooling would have made a single-path cell look bimodal and hidden that both runs are internally exact. The 2-token gap is consistent with that published path term, and a term of that size cannot account for the 5,594-token drop reported here.",
  "THE DROP IS THE HEADLINE AND IT IS LARGE": "22,801 to 17,207 is a 24.5% fall in the startup floor between 2.1.246 and 2.1.251, the largest move this site has recorded. It is reported as a measured change, not explained: nothing here establishes WHAT Anthropic removed from the system prompt or tool definitions, and no cause is asserted. The paired tool-search delta moved only +124 over the same interval, so whatever shrank is common to both arms rather than specific to tool search.",
  "three_loaded_rounds_were_refused": "result_guard refused 3 of 12 loaded-arm rounds whose stdout did not parse as JSON. They are recorded as refused rather than as zero-token runs, and the loaded figure rests on the 9 that returned. Neither floor arm lost a round."
 },
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    "OK",
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   "status": "unusable",
   "why_unusable": "stdout did not parse as JSON"
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 ]
}