The very first action in any task that will edit files must be:

test -d "$(git rev-parse --show-toplevel)/.git" && echo main || echo linked

• prints main → you are in the main worktree. Stop. Run git worktree add /tmp/librefang-<feature> -b <feature-branch> origin/main and continue all work from that path.
• prints linked → you are in a linked worktree. Continue.

Git stores the main worktree's .git as a directory and a linked worktree's .git as a text file, so the directory test is true exactly in the main worktree. Do not substitute git rev-parse --git-dir (path-shaped output, varies with cwd) or path-matching against pwd (every clone lives somewhere different).

.claude/hooks/ (Claude Code PreToolUse / SessionStart) and scripts/hooks/ (version-controlled git hooks) enforce this contract in two independent layers. Full enumeration: docs/development/ai-safety-hooks.md. The short list of things that get blocked:

• Editing files or running mutating git commands in the main worktree.
• Force-push to main / master; --no-verify / --no-gpg-sign on any git command.
• Staging sensitive files (.env*, *.pem, id_rsa, credentials*, …) and broad git add -A / git add . — stage specific paths.
• Claude / Anthropic attribution in a commit message, or a commit author identity that resolves to Claude / Anthropic.
• rm -rf against dangerous targets (/, ~, $HOME, target, .git, /usr, /etc, …).
• Launching the daemon (librefang start, target/*/librefang start|daemon) — port 4545 belongs to the user's session, and live testing is human-only.
• A changelog fragment in an unrecognised changelog.d/ section directory, or an [Unreleased] addition missing (@user) attribution.

Enable the git-side hooks once per clone: just setup (or cargo xtask setup), which sets git config core.hooksPath scripts/hooks.

LibreFang is an open-source Agent Operating System written in Rust (29 crates in crates/, plus xtask/).

• Config: ~/.librefang/config.toml
• Default API: http://127.0.0.1:4545
• CLI binary: target/release/librefang, .exe suffix on Windows (debug builds at the matching target/debug/ path)

• Core types & utilities: librefang-types, librefang-http, librefang-wire, librefang-telemetry, librefang-testing, librefang-import, librefang-subprocess (JSON-over-stdio transport for sidecar bridges)
• Kernel: librefang-kernel (orchestration), librefang-kernel-handle (trait used by runtime to call kernel without circular dep), librefang-kernel-router, librefang-kernel-metering
• Runtime: librefang-runtime (agent loop, tools, plugins, OAuth, WASM sandbox), librefang-runtime-mcp, librefang-runtime-audit, librefang-runtime-media, librefang-runtime-sandbox-docker
• LLM drivers: librefang-llm-driver (trait + error types — interface only) and librefang-llm-drivers (concrete provider impls: anthropic, openai, gemini, …)
• Memory: librefang-memory (SQLite substrate), librefang-memory-wiki (durable markdown knowledge vault)
• Surface: librefang-api (HTTP server + dashboard SPA at crates/librefang-api/dashboard/), librefang-cli, librefang-desktop, librefang-acp (ACP adapter for Zed / VSCode / JetBrains)
• Extensibility: librefang-skills, librefang-hands, librefang-extensions, librefang-channels, librefang-rl-export

Do NOT run cargo build or cargo run locally. cargo test is allowed only when scoped with -p <crate> / --package <crate> — the unscoped workspace-wide form contends with the user's other sessions on the shared target/ directory. Full workspace build / test runs in CI.

After every change:

cargo check --workspace --lib                          # Compile-check only
cargo clippy --workspace --all-targets -- -D warnings  # Zero warnings
cargo test -p <crate>                                  # Only when verifying behavior in one crate

# Quick unit-only lane, mirrors CI's Test / Unit (lib+bin):
cargo nextest run --workspace -E 'kind(lib) | kind(bin)' --no-fail-fast

docs/development/build-and-verify.md covers the rest: the two CI test lanes and why the nextest filter expression is used instead of --lib --bins, the librefang-desktop Windows exclusion (#6729), and how to verify without a native toolchain via Dockerfile.rust-dev and a per-worktree target volume. Read it before declaring a change unverified on a host that has no cargo.

Primary verification is automated: #[tokio::test] coverage in crates/librefang-api/tests/ exercises every major route domain against a real axum router via TestServer (start_test_server* in tests/api_integration_test.rs).

For any route / wiring change:

1. Add a #[tokio::test] against TestServer in the matching tests/*.rs file — spawn the router, hit the endpoint with reqwest, assert status and shape; for write endpoints, follow up with a read and assert the side effect. This is what catches missing server.rs registrations, un-deserialized config fields, kernel↔API type drift, and empty/null payloads.
2. Run scoped tests locally: cargo test -p librefang-api.
3. Reviewers gate PRs on the presence of an integration test for each new endpoint.

Live daemon + real LLM is HUMAN-only. It is needed only for LLM call paths or end-to-end prompt/metering wiring that integration tests can't simulate. Claude must not execute it — prepare the commands from docs/development/build-and-verify.md and hand them to the user.

• Deterministic prompt ordering (#3298): anything reaching an LLM prompt — tool definitions, MCP server summaries, skill / hand registries, capability lists, env passthrough lists — MUST be ordered before stringifying. Prefer BTreeMap / BTreeSet over HashMap / HashSet so the compiler enforces it; otherwise sort at the boundary. HashMap iteration order varies across processes and silently invalidates provider prompt caches even when content is unchanged. Regression tests sit next to each boundary — kernel::tests::mcp_summary_is_byte_identical_across_input_orders, kernel::tests::mcp_summary_inner_tool_list_is_sorted, librefang_skills::registry::tests::all_tool_definitions_is_deterministic_across_insertion_orders.
• Agent workspace layout: identity files (SOUL.md, IDENTITY.md, …) live in {workspace}/.identity/, not the workspace root. read_identity_file() checks .identity/ first and falls back to root for pre-migration workspaces; migrate_identity_files() runs on every spawn.
• Named workspaces ([workspaces] in agent.toml): shared directories declared with path (relative to workspaces_dir) and mode (rw / r). Agents sharing a path never collide — identity files stay in their private .identity/. Resolved absolute paths are injected into TOOLS.md as @name → /abs/path (mode). See workspace_setup.rs: ensure_named_workspaces().
• KernelHandle trait avoids circular deps between runtime and kernel; AppState in server.rs bridges kernel to API routes.
• Adding a route: there is no single routes.rs. Handlers live in crates/librefang-api/src/routes/, split per domain (agents.rs, memory.rs, system.rs, …), each exporting its own router(); server.rs::api_v1_routes() composes them with .merge(), and some domains nest a second level (routes/system.rs::router() merges agent_templates, approvals, pairing, …). Implement the handler in the matching domain module and merge its router(). Drift guards: tests/dead_route_audit_test.rs and tests/openapi_path_coverage_test.rs.
• Auth middleware allowlist: unauthenticated endpoints go in the is_public allowlist in middleware.rs — NOT by reordering routes in server.rs. The auth layer applies to all routes.
• Dashboard is a React + TanStack Query SPA (not Alpine.js) in crates/librefang-api/dashboard/. See its AGENTS.md for detail.
  • All API access in pages/components MUST go through hooks in src/lib/queries/ and src/lib/mutations/. No inline fetch() or api.* calls.
  • Query keys always come from the factories in src/lib/queries/keys.ts — never inline ["foo","bar"]. Every factory is hierarchical (all / lists() / list(filters) / details() / detail(id)) so invalidateQueries({ queryKey: xxxKeys.all }) invalidates the whole domain.
  • Every side-effecting mutation calls invalidateQueries with factory keys in onSuccess / onSettled, colocated with the mutation hook rather than at call sites.
• Config fields need all four: struct field, #[serde(default)], Default impl entry, Serialize/Deserialize derives.
• Trait injection pattern: when runtime needs functionality from extensions/kernel, define the trait in runtime and implement it in kernel (e.g. McpOAuthProvider). Never make runtime depend on extensions (circular dep).
• Docker callback URLs: never bind ephemeral localhost ports for OAuth callbacks in daemon code — unreachable from outside Docker. Route callbacks through the API server's existing port.
• MCP OAuth flow is entirely UI-driven: the daemon only detects 401 and sets NeedsAuth. PKCE + callback are handled by the API layer (routes/mcp_auth.rs); Dynamic Client Registration (RFC 7591) kicks in when a server has a registration_endpoint but no client_id.
• session_mode (in agent.toml, not config.toml) decides whether an automated invocation reuses the persistent session ("persistent", default) or creates a fresh one ("new"). Honoured by event triggers, agent_send and cron jobs; ignored by channel messages (always SessionId::for_channel) and forks (forced Persistent for prompt cache). Resolution order, the cron Persistent-vs-New session-id behaviour, and the cron_fire_session_override helper: docs/architecture/session-mode-resolution.md. When creating a trigger or cron, pick consciously — Persistent for continuity and cache reuse, New for isolation.
• Per-agent proactive_memory / skill_workshop / compaction overrides live in agent.toml, NOT config.toml (#5476). KernelConfig has no agents field, so [agents.<name>.<key>] in config.toml parses but never reaches any AgentManifest. The kernel emits a targeted WARN at boot and on POST /api/config/reload (KernelConfig::detect_misplaced_per_agent_overrides). Inside a HAND.toml the [agents.<name>.<key>] form is read, because HandManifest does have an agents table.
• Message-history trim cap is per-agent (agent.toml: max_history_messages) and global (config.toml: max_history_messages). Default DEFAULT_MAX_HISTORY_MESSAGES = 60; values below MIN_HISTORY_MESSAGES = 4 are clamped up with a warning. Resolution: agent override > kernel config > compiled default. See docs/architecture/message-history-trimming.md.
• Trigger dispatch concurrency has three layered caps scoped to the trigger dispatcher only — agent_send, channel bridges and cron still serialize on the existing per-agent / per-session locks inside send_message_full. Global Lane::Trigger semaphore (config.toml: queue.concurrency.trigger_lane, default 8), per-agent semaphore (agent.toml: max_concurrent_invocations, fallback queue.concurrency.default_per_agent default 1), per-session mutex. persistent + cap > 1 auto-clamps to 1 with a WARN (concurrent writes to one session's history are undefined). Per-agent caps are not invalidated on manifest hot-reload — kill the agent and let it respawn, or restart the daemon; an in-place activate/status flip silently keeps the old cap. See docs/architecture/trigger-dispatch-concurrency.md.
• Config hot-reload classification — which KernelConfig fields hot-reload, which need a restart, which are read-live/noop — is decided by build_reload_plan in crates/librefang-kernel/src/config_reload.rs. Consult the drift-guarded table at docs/operations/config-reload.md before assuming a config edit takes effect on POST /api/config/reload.
• Skill workshop (#3328) passively captures teaching signals from successful turns into draft skills under ~/.librefang/skills/pending/<agent>/<uuid>.toml. Default-OFF — opt in per agent with [skill_workshop] enabled = true in agent.toml (or the matching [agents.<name>] section of a HAND.toml); source of truth is SkillWorkshopConfig::default() in crates/librefang-types/src/agent.rs. Approval routes through evolution::create_skill, so the prompt-injection scan runs at both save_candidate and approve_candidate — every artefact the agent can see has crossed the same security boundary as a marketplace skill. review_mode = "threshold_llm" uses the AuxTask::SkillWorkshopReview slot on the cheap-tier provider chain, and returns Indeterminate rather than billing the primary provider when no cheap-tier credentials exist (financial-DoS guard). CLI librefang skill pending list / show / approve / reject; HTTP GET/POST /api/skills/pending[…]; dashboard PendingSkillsSection. See docs/architecture/skill-workshop.md.

• Format: conventional commits (feat:, fix:, docs:, refactor:, chore:, ci:, perf:, test:).
• No AI / Claude attribution in commit messages, PR bodies, or comments — the commit-msg hook enforces it, and so does the PreToolUse Bash hook.
• Worktree: git worktree add on an external disk for new features, falling back to /tmp/librefang-<feature>. Never develop on the main worktree.
• Worktree continuation = drive to PR. When continuing half-done work (uncommitted changes or unmerged commits), the workflow is commit → push → open or update PR; don't stop at "local commits only". Everything left in the worktree counts as real work, including a regenerated Cargo.lock after a rebase — commit it, don't git checkout it away.
• Re-entering a worktree you did not just create → git fetch and diff HEAD..origin/<branch> BEFORE editing. Collaborator pushes, the auto-update-branches cron, and the openapi-drift auto-codegen commit all move a remote tip without your involvement. Editing on a stale base and force-pushing silently clobbers that newer work; a non-fast-forward rejection is the last line of defense, not the plan.

Appending to the single ## [Unreleased] section conflicts with every other open PR doing the same, in a file where the conflict carries no information — both sides are correct and the resolution is always "keep both".

Write one fragment per entry in the section directory matching its ### heading (added/, fixed/, changed/, security/, documentation/), named after the PR or issue number so fragments sort usefully: changelog.d/fixed/6623-wire-max-content-chars.md. The file holds the bullet body without the leading - , one sentence per line, continuation lines indented two spaces, ending (#PR) (@your-github-login). A fragment in an unrecognised section directory is rejected by scripts/check-changelog-attribution.py, because assembly has no heading to render it under and would drop it silently. Format and a worked example: changelog.d/README.md.

The entry ends up in the GitHub release body verbatim, so write prose that explains why, not a restatement of the PR title. cargo xtask collect-fragments folds the fragments into ## [Unreleased] and deletes the files consumed; cargo xtask release runs it before cutting the dated section, and .github/workflows/release.yml slices that section into the release notes, Dev.to article and social post. Generated - <PR title> (#N) (@author) lines fill only the gaps: a PR whose number appears in a curated bullet's trailing (#N) group gets no generated line, so it is described once, in the words someone chose.

Do not hard-wrap at 72, 80, 100, or any other character count. The only legitimate line break inside a paragraph is at a complete sentence boundary — one sentence, one line, regardless of length. Hand-tuned column wraps split noun phrases at awkward points, force a single-word edit to re-flow the whole paragraph (polluting git blame and review diffs), and carry no semantic information.

This applies to markdown anywhere in the repo, CHANGELOG.md bullets, PR titles / bodies / comments posted via gh, source doc-comments (//!, ///, JSDoc, …) and any multi-line prose comment block, and commit message bodies. Commit subject lines still follow git's ~72-char display convention — that is a tooling limit, not prose wrapping.

The rule applies to new prose and to any paragraph you are already touching. Files written under the old convention are not retroactively rewrapped; don't rewrap an untouched paragraph just to enforce this.

Full policy, with the incidents that produced each rule: docs/development/github-collaboration.md. The rules you must not break without asking:

• Don't close, reassign, re-label or re-milestone PRs / issues opened by others unless the maintainer instructs you to. Recommend closure in a comment instead; when directed to close, state the substantive reason (review bugs, superseded by, scope mismatch).
• Force-push only to your own branches, only before review. After a reviewer has loaded the diff, prefer fixup commits or a follow-up PR.
• One PR ↔ one issue (or one tight cluster). Don't bundle unrelated refactors.
• Fix what you found — don't punt it to a "follow-up". Anything you noticed while reading or writing the code in this PR is in-scope by definition: review nits, wrong HTTP status codes, missing log fields, redundant lookups, stale comments, small clippy noise. "Follow-up", "next PR", "future cleanup", "leave for later" are red flags in your own output — they almost always mean "I saw the problem and decided to defer". Bar to defer: would fixing it require touching a different crate or domain than the one you're already in? If no, fix it now; if yes, ask the human with the concrete trade-off rather than deciding unilaterally. Re-classifying a deferred item as a "non-issue" requires file/line evidence in the same response — "I looked again and it's fine" is another form of punting.
• PR body must enumerate substantive changes, verification performed (integration test names, cargo check --workspace --lib, scoped cargo test -p <crate>), and any deferred work. Bullet form, no marketing prose.
• CI polling budget: ~5 minutes total, in 60–270 s chunks (Anthropic's prompt cache TTL is 5 min — keep each wake-up inside it). Then push, leave the run URL, and stop. Don't pre-emptively re-run a check that hasn't failed; retry once, after a recorded failure. Don't open follow-up issues or pivot the plan while waiting — report status and yield. Don't add reviewers, flip ready-for-review, or gh pr ready on someone else's behalf.
• At most two follow-up comments on a thread without human input, then stop. No "looks good" drive-bys. Every reply links evidence: commit SHAs, file paths, test names.
• Latest maintainer intent wins in conflict resolution, and preserve both sides' intent — dropping a hunk because "it'll be reapplied later" is how regressions land.
• Batch merging is runner-pool bound, not merge bound. Merging >10 PRs back-to-back saturates the free-plan ubuntu-latest pool; merge in batches, cancel superseded runs (never a run whose head_sha is its branch tip — CI Gate fails on cancelled and does not re-evaluate), and remember a stalled queue is not a CI failure.
• Two green PRs can still break main together. The main ruleset has no strict_required_status_checks_policy, so each PR merges on CI run against its own base. Group a merge sweep by changed file, re-run CI on later PRs in a group, and verify main itself after the batch.

• Windows: librefang.exe may be locked while the daemon runs — use cargo check --lib or kill the daemon first. (Linux / macOS let you overwrite a running binary.)
• Windows: use taskkill //PID <pid> //F (double slashes in MSYS2 / Git Bash).
• PeerRegistry is Option<PeerRegistry> on the kernel but Option<Arc<PeerRegistry>> on AppState — wrap with .as_ref().map(|r| Arc::new(r.clone())).
• A new KernelConfig field MUST also appear in the Default impl or the build fails.
• AgentLoopResult's field is .response, not .response_text.
• The CLI subcommand to start the daemon is start, not daemon.
• Option<Arc<dyn Trait>> fields on structs deriving Serialize/Deserialize/Clone/Debug need #[serde(skip)] plus manual impls of the affected traits.
• ErrorTranslator (from RequestLanguage) is !Send — every .await must happen AFTER drop(t), or the axum handler fails with a cryptic Handler<_, _> trait bound error.
• LIBREFANG_VAULT_KEY must base64-decode to exactly 32 bytes (openssl rand -base64 32 gives 44 chars). 32 ASCII chars ≠ 32 bytes.
• Linux desktop: zbus/tokio conflicts with Tauri's worker threads — a blocking session-bus connection (tauri-plugin-notification / notify-rust) inside a Tokio worker panics with "Cannot start a runtime from within a runtime." Force the async-io backend of the zbus / ksni crate so it runs on a separate reactor.
• CLAUDE_CODE_HOME overrides the home directory the claude-code driver hands to the spawned Anthropic claude CLI. This is a LibreFang-private contract — the Anthropic CLI does not read this variable; the driver resolves it kernel-side and projects it onto the platform-native home var ($HOME / %USERPROFILE%) before spawn. Distinct from LIBREFANG_HOME, which relocates the daemon's data dir (crates/librefang-kernel/src/config.rs: librefang_home); the two never share a value. It exists for containers that drop to a numeric uid without a passwd entry and inherit a placeholder home (/nonexistent, /var/empty, /dev/null), leaving the CLI unable to find ~/.claude/.credentials.json. The override is ignored when the inherited home is already a real directory, and when it points at a non-directory the driver logs a WARN and falls back rather than honouring it.
• When parallel agents modify the same crate, Option::None defaults for new fields compile silently but disable the feature. Always write the integration test at the injection site, not just the implementation site.