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/lib.rs

@@ -0,0 +1,54 @@
+//! kigi-sampler - Actor-based sampling layer for xAI grok.
+//!
+//! This crate extracts the HTTP streaming + retry logic out of
+//! `kigi-shell`'s session actor into a standalone, reusable
+//! component built on the same actor pattern as `kigi-hunk-tracker`.
+//!
+//! ## Layered API
+//!
+//! - **Layer 1**: [`client::SamplingClient`] returns raw chunk streams.
+//! - **Layer 2**: [`stream`] transforms raw streams into [`SamplingEvent`]s.
+//! - **Layer 3**: [`SamplerHandle`] manages concurrent requests with retry,
+//!   cancellation, and event-based coordination via the actor.
+//!
+//! The type skeleton, the pure retry / metrics / client logic, the
+//! Layer-2 stream transforms ([`stream_chat_completions`],
+//! [`stream_responses`], [`stream_messages`], [`collect_response`]),
+//! and the actor with its per-request task tie these layers together.
+
+pub mod actor;
+pub mod attribution;
+pub mod client;
+pub mod commands;
+pub mod config;
+pub mod doom_loop;
+pub mod events;
+pub mod handle;
+pub mod metrics;
+pub mod retry;
+pub mod sampling_log;
+mod shared_http;
+pub mod stream;
+pub mod types;
+
+// Public re-exports — the API surface consumers see.
+pub use actor::SamplerActor;
+pub use attribution::{
+    Auth401AttributionCallback, SENT_BEARER_PREFIX_LEN, SamplingConsumer, SharedAttributionCallback,
+};
+pub use client::{ApiBackend, SamplingClient, user_agent_string_for};
+pub use config::{
+    AuthScheme, BearerResolver, HeaderInjector, OriginClientInfo, RetryPolicy, SamplerConfig,
+    SharedBearerResolver, SharedHeaderInjector,
+};
+pub use doom_loop::DoomLoopSignalCollector;
+pub use events::{SamplingChannel, SamplingErrorInfo, SamplingErrorKind, SamplingEvent};
+pub use handle::SamplerHandle;
+pub use metrics::{InferenceLatencyStats, compute_percentiles};
+pub use retry::{
+    DEFAULT_MAX_RETRIES, RATE_LIMIT_RETRY_THRESHOLD, RetryDecision, classify_error,
+    format_sampling_error, resolve_max_retries, retry_backoff_with_jitter,
+};
+pub use sampling_log::AuthInfo;
+pub use stream::{collect_response, stream_chat_completions, stream_messages, stream_responses};
+pub use types::RequestId;