agent: builder model: opus max_turns: 100 budget_usd: 20 —
process::run with inherited streams and a stdin (#920 steps 1-3, Part #125; unblocks K3b, P5c, O2)Score: self-hosting lane. #920 is the one std gap K3b, P5c and O2 (docs/selfhosting-plan.md) wait on: Cargo’s build output reaches the user as it happens, Cargo’s JSON comes back on stdout while its progress goes to the terminal, and test binaries and comptime runs read a stdin. The forms are decided in #920 (architect, 2026-10-31): options after ;, ADR-243 style, each paying only where it is written (default keeps today’s behaviour byte for byte).
Facts: Where things live, Traps already met, Commands
stdout: process::Stream = process::Stream::Captured, stderr: process::Stream = process::Stream::Captured, enum Stream { Captured, Inherited }; an inherited stream’s text in Output is "".stdin: process::Input = process::Input::Closed, enum Input { Closed, Inherited, Text(String) }; Text is written by a thread of its own while the pipes are read (no deadlock on a child that writes before it reads), then closed. A child that exits before reading all of it is no failure (a broken pipe on that write is ignored).;: the existing ones unchanged, then stdin, stdout, stderr (append; Part III says the order).within: keeps working with inherited streams (the process group kill does not depend on the pipes).30-nikaia-tooling.md :1526ff), an amendment section in docs/specification/adr/adr-243.md (D10, citing #920), std.contracts entries beside process::run’s. No version line, no CHANGELOG (the supervisor’s): say under Changelog: what it decided.crates/nikaia-std/src/process.rs (run :160ff, Command built at :86-102: .stdin(Stdio::null()), .stdout/.stderr(Stdio::piped())); crates/nikaia-std/std.contracts (grep -n "process::" ); how an option after ; reaches the Rust fn: follow env_clear (nikaia run scripts/where.nika -- env_clear), the pattern to copy for every layer it passes (contracts, emitter call, std signature).
Stream and stdout:/stderr:, spec, ADR amendment, contracts.Input and stdin:.tests/compiler/tests/process_inherit.nika (+ .stdout, .stderr if needed): a child (sh -c, as the existing process_* tests start one: ls tests/compiler/tests/process_*) that prints with stdout: Inherited (its line appears in the test’s own stdout, and Output.stdout is ""), one with stdout captured and stderr inherited, one that reads a stdin: process::Input::Text("…") and echoes it, one with the defaults (unchanged).
Commit per step; the last std: process::run takes stdin, stdout and stderr options (Fixes #920).The new test passes with nikaia test --project tests/compiler --both-settings on it (singly: gate_test_some), the existing tests/compiler/tests/process_* tests pass, cargo test --profile fast -p nikaia --test it -- process passes, clippy (also cargo +1.99.1, builder-facts Traps already met), fmt, pre-push-check.sh. Stop about 15 turns before max_turns, commit what is finished, Result: partial.
An option form the existing ; options cannot carry (a defaulted enum value, process::Input::Text(..) as an argument) fails in check or lowering: that is a Found: with a probe, not code around it; an edit needed outside process.rs, std.contracts, Part III, ADR-243, the files the option path passes (name them in Body:) and the test; an error in another agent’s file.
Not yours, never stage: every file git status shows modified or untracked at your start (today among them crates/nikaia-std/src/tools/lowered/project_members.rs, crates/rs2nika/convert/*, crates/rs2nika/facts/*, docs/briefs/*.report.md), and every docs/briefs/* file except your report.
docs/builder-facts.md first. develop in the main checkout; git status at start: other agents’ uncommitted files are not yours, never touch or stage them.git add <files> only (scripts/commit.nika -- REPORT does it); commit locally after each step and never push: the driver runs the complete suite and pushes (.claude/agents/builder.md, Cheap checks only; owner, 2026-10-31).cargo build --profile fast -p nikaia, lower-std and its fixpoint when a tools/*.nika changed, cargo fmt, cargo clippy --all-targets -- -D warnings, scripts/pre-push-check.sh, the tests the brief names and the ones your change touches. No gate.nika.CHANGELOG.md, badges; no new NK code. New tests in Nikaia only; never the full suite. No foreground sleep, no polling; scripts in files.std or the toolchain lacks stops the work: no code around it unless an ADR or Part I-III refuses it (name it). Else Result: blocked, Found: gap + probe, Needs: architect decision (CLAUDE.md, A missing form stops the work).NIKAIA_CACHE_LIMIT=2G; at most two clones with target/ in the machine; delete your own clone’s target/ and target/release/nikaia-scratch at the end; report GB freed.Result: partial with what you ruled out, the probe, and the suspected file and function (.claude/agents/builder.md).target/fast/nikaia run scripts/commit.nika -- REPORT, which writes Pushed: local <sha> into it. A report without a Pushed: line, or with a placeholder left in (TC, DISK), is not done and cuts the batch (k3a1 2026-10-29: Result: done, nothing committed)./home/user/Nikaia/docs/briefs/s920-process-streams.md.report.md)Fields of docs/architect.md, Briefs and reports: Result: done|noop|partial|blocked (the bare word alone on that line: Result: done, never a summary after it, which cuts the batch, b869a 2026-10-27; Owner: is a question for the owner or none, never a role), Files, Commit, Body (optional, one paragraph for the commit message), Fixes, Pushed, Tests, Gate (green|red), Deviation, Found, Needs, Changelog, Owner, Disk freed, and for a move Rs2nika: (the kept N of M lines of rs2nika --score, then the three costliest hand edits; none for a task that moves no Rust, none (redesign) for a brief with Shape: redesign and no Convert: line). none where nothing, and then the bare word: Deviation: none (a note) cuts the batch (batch.nika compares exactly); a note goes into the commit message. Found: is only for a defect outside your change (it cuts the batch); a process event such as another session resetting or rewriting your files is no Found:, it goes under Needs: (m3a 2026-10-28); a converter draft that came out wrong is no Found:, it is one of the costliest edits under Rs2nika:, which the converter lane reads (e12-4b 2026-10-27); how you solved your own step goes into the commit message. Deviation: is only a step of the brief built otherwise than written or not built (a choice the brief left to you, such as keep what X needs and say so, is no deviation: it goes into the commit message; nor is building two steps in one commit when every step is built, e12-3a 2026-10-27, nor a step another commit on develop already built, shown by your test failing with that commit’s change reverted, b889 2026-10-27: name the commit in Body:, nor a test’s expected .stdout/.stderr taken from what the program really prints where the brief’s sketch of it was short or wrong, b934 2026-10-29: say so in Body:, nor a lowering that follows the ADR governing it where the brief’s expected lowering contradicts that ADR, b933 2026-10-29: name the ADR in Body:, nor a lowering other than the brief’s where rustc cannot take the brief’s, b1029 2026-10-31: say why in Body:, nor re-keying an allow-list entry (KNOWN) whose hash changed for the same program and the same reason, b-fixforward-sweep2 2026-10-28: say so in Body:, nor an existing test’s expected .stdout/.stderr updated because your change rightly changes the message it prints, b1012b 2026-10-31: name the test in Body:); how you verified (e.g. a test not run against the unfixed compiler) goes under Tests:. A noop says why under Tests: (what was probed), not under Deviation:. Final answer, one line: done <sha>, report <path> (or BLOCKED: ... / PUSH REJECTED ...).
Attribution: Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com Claude-Session: https://claude.ai/code/session_01GFeMqxRbtUMiGVyDMxsvEq