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-log/src/session_ctx.rs

@@ -0,0 +1,53 @@
+//! Ambient per-session tracing span for log routing.
+//!
+//! The `--debug` firehose router ([`crate::debug_log`]) fans events out to
+//! `~/.kigi/debug/<session_id>.txt` by finding the enclosing session span's
+//! `session_id` field. [`with_session_ctx`] installs that span for the
+//! duration of a session's work.
+
+/// The `session_id` field name the debug-log firehose router keys on:
+/// `debug_log::SessionIdVisitor` stashes a `SessionId` extension on any span
+/// carrying this field — the span *name* is not load-bearing for routing. Shared
+/// so the `info_span!` here and the router in `debug_log` can't silently drift; a
+/// rename trips `session_span_exposes_router_field` below.
+pub(crate) const SESSION_ID_FIELD: &str = "session_id";
+
+/// Build the per-session tracing span the firehose router routes by. The field
+/// name MUST be the literal `session_id` (tracing field names can't come from a
+/// const); the test below pins it against [`SESSION_ID_FIELD`].
+fn session_span(session_id: &str) -> tracing::Span {
+    tracing::info_span!("session", session_id = %session_id)
+}
+
+/// Run `fut` inside the per-session tracing span so the debug-log firehose
+/// routes its events to the session's file.
+pub async fn with_session_ctx<F: std::future::Future>(session_id: &str, fut: F) -> F::Output {
+    use tracing::Instrument;
+    fut.instrument(session_span(session_id)).await
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// The debug-log firehose router (`debug_log`) finds the session span by its
+    /// `session_id` field (not by name). That field name is a literal in
+    /// `session_span` (tracing field names can't be a const), so pin it against the
+    /// shared const here — a rename of either breaks this test instead of silently
+    /// degrading routing to the per-pid fallback.
+    #[test]
+    fn session_span_exposes_router_field() {
+        // A bare registry enables every callsite, so the span has live metadata.
+        let subscriber = tracing_subscriber::registry();
+        tracing::subscriber::with_default(subscriber, || {
+            let span = session_span("test-id");
+            let meta = span
+                .metadata()
+                .expect("session span must have metadata under an enabling subscriber");
+            assert!(
+                meta.fields().field(SESSION_ID_FIELD).is_some(),
+                "session span must expose `{SESSION_ID_FIELD}` for debug-log routing",
+            );
+        });
+    }
+}