M0: compilable skeleton — Kigi 0.1.0 fork surgery

Hard fork of xai-org/grok-build (Apache-2.0) re-targeted as Kigi, an
unofficial Kimi Code CLI community build.

Rename & identity
- 72 xai-*/xai-grok-* crates -> kigi-* (explicit: xai-grok-pager-bin ->
  kigi-bin [binary `kigi`], xai-grok-pager -> kigi-tui; rest mechanical);
  ptyctl, ptyctl-cli, third_party/ unchanged; proto package
  xai.grok.tools.v1 -> kigi.tools.v1
- Config home ~/.kigi (KIGI_SHARE_DIR override), env prefix GROK_* ->
  KIGI_*, `kigi --version` carries the unofficial-community-build notice
- clap identity, help text, startup banner, prompt templates rebranded
  (templates re-encrypted)

Deletions (PRD removal list #5/#6/#7/#9/#10)
- voice input (xai-grok-voice) and all TUI wiring
- telemetry: Mixpanel client, external OTel stream, Sentry, OTLP layers,
  trace/GCS/S3 upload queues (kigi-file-utils halved), workspace upload
  module & dc_log, heap-profile uploader, auth-diagnostics uploader,
  session-analytics halves of feedback; local zero-egress observability
  preserved in new kigi-log crate (unified log, --debug firehose,
  subsystem file logs, opt-in instrumentation)
- announcements (crate, remote-settings fields, TUI surfaces)
- plugin marketplace (crate, sources/browse/CTA/extensions-modal tab);
  direct plugin install/uninstall/update via kigi-agent git_install kept
- relay/gateway/assets endpoints and features (agent relay, headless
  relay transport, gateway bridge, LeaderEnvUrls); leader IPC socket now
  ~/.kigi/leader.sock + KIGI_LEADER_SOCKET, no ws-url derivation
- functional types rehomed instead of deleted: PermissionMode ->
  kigi-config-types, McpInitStrategy -> kigi-mcp, PrCreationSource ->
  session signals, TerminalDiagnostics -> kigi-pager-render, agent_id ->
  shell util

Endpoints
- kigi-env rewritten: single production KigiEndpoints {coding_api_base_url
  https://api.kimi.com/coding/v1 (KIGI_CODE_BASE_URL), oauth_host
  https://auth.kimi.com (KIGI_OAUTH_HOST), update_base_url (GitHub
  Releases API), upgrade_page_url}; GrokBuildEnvironment enum deleted

Toolchain & workspace hygiene
- Rust 1.97.0 pinned; edition 2024; full cargo update; git2 hoisted to
  workspace at 0.21 (Option->Result API migration), quick-xml 0.41
- Root Cargo.toml hand-maintained (PRD §8.1): version 0.1.0 inherited by
  all members, members sorted, unused deps pruned
- cargo-deny advisories gate (deny.toml with documented transitive
  exceptions); CI workflow (check/clippy/fmt/deny/test, macOS+Linux)
- cross-crate test seams re-gated behind `test-support` cargo feature;
  insta snapshot baselines renamed to the kigi_tui prefix
- clippy --workspace --all-targets: zero warnings; fmt clean

Fixes surfaced by the port
- updater probe/installer divergence (bin/kigi vs bin/grok symlink set)
- idle model-metadata refresh dead under KIGI_CODE_BASE_URL override
  (new is_effective_coding_endpoint_url, loopback+override aware)
- macOS symlinked-TMPDIR fixture canonicalization (foreign_sessions,
  fast-worktree); RSS measurement tests serialized via serial_test

Docs & legal (Apache §4)
- NOTICE added (upstream attribution + change statement); THIRD-PARTY
  notices sustained; kigi-tools ported-code notices extended; README,
  CONTRIBUTING, SECURITY, AGENTS.md rewritten

Out of scope for M0 (tracked): Kimi auth/inference (M1), search/fetch,
command parity, config import (M2), Computer Hub excision & final
brand-token sweep (M2), distribution & self-update rewrite (M3).

crates/codegen/kigi-sampler/src/attribution.rs

@@ -0,0 +1,120 @@
+//! 401 attribution callback hook for the sampling client.
+//!
+//! Every 401 response site can optionally emit an attribution event so
+//! a downstream observer can split production 401s into "client sent a
+//! stale snapshot bearer that the server rejected" vs. "client sent
+//! the live token from its auth source and the server still rejected
+//! it" buckets.
+//!
+//! `kigi-sampler` is intentionally decoupled from `kigi-shell`
+//! (no shell types, no logging crate, no auth-manager dependency). The
+//! caller wires an implementation of [`Auth401AttributionCallback`]
+//! into [`crate::SamplerConfig::attribution_callback`]; the sampler
+//! invokes the callback at each UNAUTHORIZED arm with the bearer that
+//! was actually sent on the wire. The implementation is free to join
+//! the bearer with whatever live credential source it owns and emit
+//! the attribution however it wants.
+//!
+//! When the callback is `None` (the default), the 401 sites are silent
+//! and return the same `SamplingError::Auth` they would otherwise.
+
+use std::sync::Arc;
+
+/// A logical 401-emitting site inside the sampling client. The string
+/// identifier ends up in the consumer field of the attribution event
+/// so downstream queries can break down 401s by API path.
+///
+/// # Scope: sampler endpoints only
+///
+/// This enum enumerates the six HTTP endpoints owned by
+/// `SamplingClient` (chat completions, responses, messages -- each in
+/// streaming and non-streaming form). It does *not* cover image
+/// generation, video generation, web search, or embedding -- those
+/// tools live in `kigi-tools`
+/// (`crates/codegen/kigi-tools/src/implementations/`), have their
+/// own HTTP clients that do not flow through `SamplingClient`, and
+/// hook into the `kigi_tools::ApiKeyProvider` trait rather than
+/// this enum.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum SamplingConsumer {
+    /// `chat_completion_stream`: OpenAI-compatible streaming OpenAI Chat Completions API.
+    ChatCompletionsStream,
+    /// `chat_completion`: OpenAI-compatible non-streaming OpenAI Chat Completions API.
+    ChatCompletions,
+    /// `create_response_stream`: Responses API streaming.
+    ResponsesStream,
+    /// `create_response`: Responses API non-streaming.
+    Responses,
+    /// `messages_stream`: Anthropic Messages API streaming.
+    MessagesStream,
+    /// `messages`: Anthropic Messages API non-streaming.
+    Messages,
+}
+
+impl SamplingConsumer {
+    /// Stable string identifier for this emit site. Callbacks
+    /// typically combine this with a fixed prefix (e.g. the client
+    /// type) when building the consumer field of the attribution
+    /// event.
+    pub fn as_endpoint(self) -> &'static str {
+        match self {
+            Self::ChatCompletionsStream => "chat_completions_stream",
+            Self::ChatCompletions => "chat_completions",
+            Self::ResponsesStream => "responses_stream",
+            Self::Responses => "responses",
+            Self::MessagesStream => "messages_stream",
+            Self::Messages => "messages",
+        }
+    }
+}
+
+/// Maximum prefix length the sampler shares with attribution
+/// callbacks across the crate boundary. Mirrors
+/// `kigi_shell::auth::token_suffix` (which truncates to 12 chars
+/// before any sink) so the two crates stay in lock-step on the
+/// "bearers leaving the sampler are 12-char prefixes only" invariant.
+///
+/// The cross-crate boundary is the only place this constant is
+/// load-bearing -- changing it requires updating `token_suffix` in
+/// `kigi-shell/src/auth/manager.rs` to match, otherwise the
+/// shell's local-log payload and the sampler's callback argument
+/// will disagree on prefix length.
+pub const SENT_BEARER_PREFIX_LEN: usize = 12;
+/// Hook invoked by [`crate::SamplingClient`] at every 401 response site.
+///
+/// Implementations are responsible for joining `sent_bearer_prefix`
+/// with whatever live credential source they own (e.g. an auth
+/// manager holding the most-recently-refreshed token) and emitting
+/// whatever attribution event makes sense for their observability
+/// stack.
+///
+/// Implementations must be cheap to invoke and must not block. They
+/// run inside the request's response-handling path and any latency
+/// they add is paid by the user-visible 401 error path.
+//
+// The `Debug` bound is a structural requirement: [`crate::SamplerConfig`]
+// derives `Debug` and carries an `Option<Arc<dyn Auth401AttributionCallback>>`
+// field, which only compiles when the trait is `Debug`. Do not remove
+// the bound when factoring this trait out -- it will break
+// `derive(Debug)` on `SamplerConfig`.
+pub trait Auth401AttributionCallback: Send + Sync + std::fmt::Debug {
+    /// Record a 401 attribution event for one logical 401 response.
+    ///
+    /// `sent_bearer_prefix` is the **first
+    /// [`SENT_BEARER_PREFIX_LEN`] characters** of the bearer that
+    /// was actually sent on the wire. The sampler extracts the
+    /// bearer from the `Authorization` header (or `x-api-key` for
+    /// Anthropic Messages API backends) and truncates it to the prefix
+    /// length **before crossing this trait boundary** -- the full
+    /// bearer never leaves [`crate::SamplingClient`]. This is the
+    /// scrub-at-the-boundary invariant: even a misbehaving callback
+    /// implementation that logs `sent_bearer_prefix` directly leaks
+    /// only the prefix, never the full credential.
+    ///
+    /// `None` indicates the request had no bearer header at all
+    /// (distinct from "had a bearer that turned out to be stale").
+    fn record_401(&self, consumer: SamplingConsumer, sent_bearer_prefix: Option<&str>);
+}
+
+/// Shared, cheap-to-clone alias for the attribution callback.
+pub type SharedAttributionCallback = Arc<dyn Auth401AttributionCallback>;