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/common/kigi-compaction/src/lib.rs

@@ -0,0 +1,83 @@
+//! Shared, transport-agnostic compaction engine.
+//!
+//! This crate is the `compaction-core`: shared policy, prompts, selection,
+//! and assembly. Host-specific trigger wiring, transport, persistence /
+//! replay / rewind, state commit, metrics backends, and prompt-variant forks
+//! stay in each product host (for example `kigi-shell`).
+//!
+//! The crate depends on **neither** a conversation-type crate nor
+//! `kigi-sampling-types`. It is decoupled from both Grok chat and
+//! grok-build hosts through a small set of trait seams:
+//!
+//! - [`CompactionItem`] / [`CompactionRole`] / [`CompactionItemBuilder`] —
+//!   abstracts a single turn and its reconstruction.
+//! - [`ItemTokenCounter`] — trusted token counting per host.
+//! - [`CompactionSampler`] — the LLM call.
+//! - [`CompactionStreamProc`](intra_compaction::CompactionStreamProc) —
+//!   state commit for intra-compaction.
+//! - [`IntraCompactionObserver`](intra_compaction::IntraCompactionObserver) /
+//!   [`InterCompactionObserver`](inter_compaction::InterCompactionObserver)
+//!   — host metrics.
+//!
+//! Compaction styles live in their own modules:
+//!
+//! - [`code_compaction`] — grok-build's whole-session **full-replace**
+//!   subsystem (prompt/summary/failure/config, assemble, orchestration).
+//! - [`intra_compaction`] — Grok chat's tail-keep, per-step pass.
+//! - [`inter_compaction`] — Grok chat's chunked, between-turn pass.
+//!
+//! Compaction-type content (parallel subfolders): [`steps`] (the step-level
+//! prompt) and [`history`] (filtering, history prompts, validation +
+//! user-query preservation).
+//!
+//! Shared seams/primitives: [`item`], [`token`], [`sampler`],
+//! [`prompt::CompactionPrompt`], [`select`] (tool-pair-safe tail-keep
+//! selection — shared by the intra `Steps` and `History` targets, so it stays
+//! neutral at the crate root rather than under `steps`), and [`reminder`]
+//! (active-agent-state `<system-reminder>` formatting shared by Grok chat and
+//! grok-build; hosts still own snapshotting and host-only sections).
+
+pub mod code_compaction;
+pub mod history;
+pub mod inter_compaction;
+pub mod intra_compaction;
+pub mod item;
+pub mod prompt;
+pub mod reminder;
+pub mod sampler;
+pub mod select;
+pub mod steps;
+pub mod token;
+
+/// Shared code default for the dedicated compaction model name.
+///
+/// Override order (highest first):
+/// 1. the agent's `compaction_model_name` setting (non-blank)
+/// 2. service / harness config YAML
+/// 3. this constant
+pub use intra_compaction::DEFAULT_COMPACTION_MODEL_NAME;
+
+// grok-build's full-replace subsystem now lives under `code_compaction`;
+// re-exported at the crate root so consumers keep a stable public API.
+pub use code_compaction::{
+    CompactedHistoryParts, DEFAULT_AUTO_COMPACT_THRESHOLD_PERCENT, FailureKind,
+    FullReplaceAttemptOutcome, FullReplaceConfig, FullReplaceContext, FullReplaceError,
+    FullReplaceObserver, FullReplaceOutput, FullReplaceSummary, MIN_SUMMARY_SEED_CHARS,
+    SELF_SUMMARIZATION_PROMPT, SummaryPromptKind, apply_full_replace_compaction,
+    assemble_compacted_history, build_summary_prompt, build_summary_prompt_kind,
+    classify_http_status, classify_stream_event_error, format_compact_summary,
+    format_compact_summary_content, is_context_length_error, is_degenerate_summary,
+    sample_full_replace_summary, wrap_user_query,
+};
+pub use item::{
+    CompactionFileRef, CompactionItem, CompactionItemBuilder, CompactionItemFactory, CompactionRole,
+};
+pub use prompt::CompactionPrompt;
+// Reminder types/formatters: import from `reminder::` (borrowed views).
+// Only the summary-injection helper is re-exported at the crate root — both
+// intra FullReplace and inter already use it by this name.
+pub use reminder::append_reminder_block;
+pub use sampler::{CompactionSampleError, CompactionSampler, LlmCompactionOutput};
+pub use select::{SplitPlan, select_turns_to_compact};
+pub use steps::format_compaction_prompt;
+pub use token::ItemTokenCounter;