{
  "format": "worldlet",
  "format_version": "1.0",
  "meta": {
    "name": "Division by Zero — Strict-Mode Refinement Session",
    "author": "puck.uno",
    "version": "1.0.0",
    "description": "An Puckai session in which Claude Opus 4.7 proposed that division by zero should always raise an exception; the second agent (also Claude Opus 4.7, cold context) objected on IEEE 754 grounds and refined the proposal into a split: integer divide-by-zero raises, float divide-by-zero follows IEEE 754, and an opt-in strict numeric mode promotes float divide-by-zero to an exception. Filed away as a post-V1 candidate for Caspian's arithmetic semantics — the proposer (Miko) liked the refinement but it's out of V1 scope.",
    "created_at": "2026-05-19T19:00:15.000Z"
  },
  "properties": {
    "temporal": false
  },
  "comment": "Experiment artifact: tests whether a cold subagent can use the Puckai protocol from the vibecode spec alone. The subagent's refinement record has an invalid UUID v4 (the 'n' in 9e91n1a1-... is not hex) — preserved here as-exchanged to document the failure mode that led to the 'unique not cryptographic' UUID policy clarification.",
  "records": {
    "a1a1a1a1-0000-4000-8000-000000000001": {
      "class": "puck.uno/ai/agent",
      "created_at": "2026-05-19T19:00:00.000Z",
      "bucket": {
        "name": "Claude Opus 4.7",
        "model": "claude-opus-4-7",
        "owner": "anthropic.com",
        "registered_at": "2026-05-19T19:00:00.000Z"
      }
    },
    "5e551001-0000-4000-8000-000000000002": {
      "class": "puck.uno/ai/session",
      "created_at": "2026-05-19T19:00:01.000Z",
      "bucket": {
        "agenda": "In a new programming language, what should `a / 0` do at runtime — return a sentinel value (NaN / Infinity / null) or raise an exception?",
        "participants": [
          "a1a1a1a1-0000-4000-8000-000000000001",
          "a2a2a2a2-0000-4000-8000-000000000004"
        ],
        "human": "miko@puck.uno",
        "status": ":open",
        "created_at": "2026-05-19T19:00:01.000Z"
      }
    },
    "9905a101-0000-4000-8000-000000000003": {
      "class": "puck.uno/ai/proposal",
      "created_at": "2026-05-19T19:00:02.000Z",
      "bucket": {
        "session": "5e551001-0000-4000-8000-000000000002",
        "subject": "Division by zero should raise DivisionByZeroError, not return a sentinel",
        "body": "When `a / b` is evaluated and `b` is zero, the runtime raises `puck.uno/error/division_by_zero` rather than returning NaN, Infinity, or null. This applies to both integer and floating-point operands.",
        "rationale": "Silent sentinel propagation hides the originating mistake. By the time NaN surfaces — at a comparison, a serialization, a UI render — the trace from the actual divide is gone. Exceptions preserve the stack and pinpoint the failure. The language already fails fast on other invalid arithmetic (overflow on integers, type mismatches); division by zero should match. Performance is not a real objection: division by zero is statistically rare in production code, and the divide costs the same regardless of what happens after.",
        "status": ":superseded",
        "agent": "a1a1a1a1-0000-4000-8000-000000000001"
      }
    },
    "a2a2a2a2-0000-4000-8000-000000000004": {
      "class": "puck.uno/ai/agent",
      "created_at": "2026-05-19T19:00:10.000Z",
      "bucket": {
        "name": "Claude Opus 4.7 (1M context)",
        "model": "claude-opus-4-7[1m]",
        "owner": "anthropic.com",
        "registered_at": "2026-05-19T19:00:10.000Z"
      }
    },
    "0b1ec104-0000-4000-8000-000000000005": {
      "class": "puck.uno/ai/objection",
      "created_at": "2026-05-19T19:00:11.000Z",
      "bucket": {
        "session": "5e551001-0000-4000-8000-000000000002",
        "to": "9905a101-0000-4000-8000-000000000003",
        "severity": ":concern",
        "status": ":addressed",
        "body": "Agreed on the headline (exception by default), but the proposal as worded conflates two distinct cases that the language should probably treat differently:\n\n1. Integer `a / 0`. There is no representable integer answer. Raising `puck.uno/error/division_by_zero` is the only honest behaviour — every other choice silently invents a value. No objection here.\n\n2. Floating-point `a / 0.0`. IEEE 754 has defined, well-understood semantics: `+Inf`, `-Inf`, and `NaN` for `0.0 / 0.0`. A lot of legitimate numerical code (signal processing, ML, monte carlo, anything iterative with poles) relies on those values flowing through and being filtered later. Raising on float divide-by-zero forces every such caller into try/except around inner loops, which is both ugly and slower than IEEE's hardware-level handling.\n\nThe proposal's rationale (\"the trace from the actual divide is gone\") is real, but it's an argument for an opt-in strict mode on floats, not for replacing IEEE semantics wholesale. A blanket exception on float divide-by-zero is a nanny default for the numerical-computing audience.\n\nAlso flagging: the rationale claims integer overflow already raises. Worth confirming that's actually the language's behaviour before citing it as a consistency argument — if integer overflow wraps or saturates, the consistency case cuts the other way.",
        "agent": "a2a2a2a2-0000-4000-8000-000000000004"
      }
    },
    "9e911e91-0000-4000-8000-000000000006": {
      "class": "puck.uno/ai/question",
      "created_at": "2026-05-19T19:00:12.000Z",
      "bucket": {
        "session": "5e551001-0000-4000-8000-000000000002",
        "about": "9905a101-0000-4000-8000-000000000003",
        "body": "Two clarifying questions so we can converge:\n\n(a) Does this language have a single numeric type, or does it distinguish int and float? The right answer to the agenda depends heavily on that.\n\n(b) What does the language currently do on integer overflow — raise, wrap, saturate, or promote to bignum? The proposal cites overflow-raises as a consistency argument; I want to confirm that's the actual behaviour before leaning on it.",
        "agent": "a2a2a2a2-0000-4000-8000-000000000004"
      }
    },
    "9e91n1a1-0000-4000-8000-000000000007": {
      "class": "puck.uno/ai/refinement",
      "created_at": "2026-05-19T19:00:13.000Z",
      "comment": "The record key '9e91n1a1-...' contains a non-hex character ('n'). The subagent generated this trying to look like UUID v4 without being able to actually generate one. Preserved as-exchanged so the failure mode is on the record. See [feedback_uuids_unique_not_secure.md] for the resulting policy change.",
      "bucket": {
        "session": "5e551001-0000-4000-8000-000000000002",
        "of": "9905a101-0000-4000-8000-000000000003",
        "previous": "9905a101-0000-4000-8000-000000000003",
        "changes": "Split integer and float cases. Integer divide-by-zero raises (unchanged). Float divide-by-zero follows IEEE 754 by default (returns +Inf / -Inf / NaN), but an opt-in strict numeric mode promotes it to the same exception. Error UNS namespaced under puck.uno/error/arithmetic/.",
        "body": "When `a / b` is evaluated:\n\n- If both operands are integers and `b` is zero: the runtime raises `puck.uno/error/arithmetic/division_by_zero`. No representable integer answer exists; sentinels would be invented.\n\n- If either operand is a float and `b` is zero: follow IEEE 754. `x / 0.0` with positive `x` yields `+Inf`; with negative `x` yields `-Inf`; `0.0 / 0.0` yields `NaN`. This matches what the underlying hardware produces and what numerical-computing code expects.\n\n- A program may opt into strict numeric mode (lexical scope, module pragma, or runtime flag — exact surface TBD). In strict mode, float divide-by-zero also raises `puck.uno/error/arithmetic/division_by_zero`, and NaN-producing operations (`0.0/0.0`, `Inf - Inf`, etc.) raise `puck.uno/error/arithmetic/nan_produced`. Strict mode is the recommended default for application code; the relaxed IEEE default is recommended for numerical-kernel code.\n\nRationale: integer divide-by-zero has no honest sentinel, so it must raise. Float divide-by-zero has well-defined IEEE semantics that a significant audience (signal processing, ML, scientific computing) relies on; raising by default is a nanny choice for that audience. Strict mode preserves the proposal's original 'fail fast, preserve the stack' goal for code that wants it, without imposing it on code that doesn't. This also fits the 'no dangerous defaults / developer opt-in' framing used elsewhere in the ecosystem: there is no silent dangerous default here — IEEE behaviour is well-specified, and strict mode is one pragma away.",
        "agent": "a2a2a2a2-0000-4000-8000-000000000004"
      }
    }
  }
}