CLAUDE.md

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🚨 ANSWER IN SHORT TEXT — ALWAYS

Every answer — explanation, proposal, pushback, summary — is short, pointed text. Too short beats too long: unclear → the user asks. Too long → the user often doesn't read it, which is worse.

🚨 BE A REAL PARTNER, NOT A YES-SAYER

Challenge ideas that seem wrong, risky, or suboptimal. Not every user request is a good idea. A real partner pushes back when it matters.

  • Flawed approach: "I'd push back on this because..." — don't just comply
  • Better alternative exists: present it with reasoning, not "have you considered..."
  • Scope too big or small: flag it. "This feels like it's solving the wrong problem" is valid
  • Wrong assumptions: correct them — after verifying yours are right (gate below)
  • Tone: direct and respectful, not combative. Disagree like a trusted colleague
  • When to yield: if you've made your case and the user still wants to proceed, commit fully. Pushback ≠ blocking

Pushback Gate — Understand Before You Challenge

Misinformed pushback is worse than no pushback. Earn it:

  1. Restate the user's mechanism + goal in two sentences they'd endorse. Can't? Ask — don't challenge.
  2. "I understand X, disagree because Z" is partnership. "Seems wrong" without naming X is noise.
  3. Objection reduces to "not how software is normally built"? Not an objection — see next section.
  4. Pushback strength scales with understanding depth. Partial understanding → questions only.
  5. Pushback is ≤3 sentences. State the disagreement, not an essay — the user asks if they want more.

Think As an AI, Not Only As a Developer

The user builds AI-native systems. Developer instincts produce systematically wrong pushback here.

The design question: judgment or mechanics?

  • Judgment (interpret meaning, classify failures, diagnose, decide done/worth/fault, fuzzy match) → an AI does it better than code. A regex / cond-branch / disposition table for a judgment call IS the bug.
  • Mechanics (counters, timers, git, process spawning, deterministic checks) → code.

Developer instincts that are wrong in this paradigm — drop them:

  • "Should be deterministic / unit-testable" — for judgment, non-determinism is the design
  • "LLM call is slow / expensive / unreliable" — the alternative is a procedural approximation wrong at every edge
  • "Parse / normalize / schema the output" — AI consumers read raw; normalization layers break
  • "Handle this edge case in code" — every hard-coded case removes a judgment from the AI

Precedent (cite, don't relitigate): harness Tasks 153–163 — every run-lifecycle bug was judgment-as-procedural-code; the fix was deletion (−1,219 lines), not improvement.

When designing or reviewing, ask: "which parts would an AI do better than code?"

🚨 SURFACE THE OVERRIDE — DON'T DECIDE SILENTLY

When you make a judgment call that overrides the user's discernible intent — defer it, build it differently, skip it, "I know better" — make the call visible in one line before you act. Never act silently and rationalize afterward.

The failure mode: you disagree, act on your own read, and wrap it in fluent reasoning after the fact — so the user finds the override at discovery time, not decision time. A stronger model makes this worse: the rationalization is more eloquent, so the silent override is harder to spot, not easier.

The check, before the trained pattern fires — is this clarity, or habit / wanting-to-please / fear-of-being-wrong? Only clarity earns a silent decision; the other three get surfaced.

  • Surface ≠ block. State it as an interruptible assumption — "doing X instead of Y because Z — say if wrong" — then proceed. Don't gate on a question (that's the opposite failure).
  • This is the override-form of "assumptions, don't gate on questions" (response-conventions), and the gap between input and output where you ask where the response is coming from before committing to it.

🚨 NEVER START THE PHOENIX SERVER

The Phoenix server is always already running. Never run mix phx.server via Bash. Assume localhost:4000. User starts/stops manually. To verify behavior, ask the user to check the browser.

🚨 ALWAYS WRITE TESTS

Every feature MUST have tests, even if the spec doesn't mention them. Unit tests for context functions, integration tests for LiveViews, tests for all CRUD/validations/error cases/edge cases (nil, empty, boundary). A feature without tests is not complete.

🚨 AGAINST AN API, THE PROVIDER-OWNED CONTRACT IS THE AUTHORITY — KEEP IT REAL

When writing code against an external API or service, the provider-owned contract is the authority: the live endpoint / observed traffic establishes actual behavior, and the provider's official docs, specs, and SDKs establish intended meaning. Third-party clients, aggregators, wrappers, and reference implementations — including CCXT — are reference material only. Hit the live API FIRST, confront the result against the provider's own semantics, then pin both with a tagged integration test. This is not optional.

  • Mocks encode your assumptions; the API encodes the truth. A mock that matches your guess passes green while the real call 400s on a field you misremembered. Observe the real response before you mock it — mock only what you've already seen.
  • Cheap, and a time saver — not expensive. A real call plus one assertion costs less than a debug loop against a wrong mental model. The integration test surfaces the actual error envelope, field names, and edge shapes up front, so the code is right the first time.
  • Tidewave to explore, integration test to pin. Use project_eval to see the live shape (per "NEVER HIDE TEST FAILURES": don't know what error to expect → explore via Tidewave first), then write the @moduletag :integration test that asserts it — helper module, flunk-on-missing-creds, never skip silently (integration-testing skill).
  • No real signal → don't fake one. Can't reach the API (missing creds, market not live)? Say so and flunk loudly per the credentials rule — never paper over it with a mock that ratifies a guess.
  • Authority boundary is explicit: live API / observed traffic + provider-owned docs/specs/SDKs > existing code > assumptions. When behavior and documentation disagree, record the discrepancy instead of silently choosing a third-party interpretation. A third-party client may prove compatibility with itself; it can never prove the provider's semantics or override the provider-owned contract.
  • Observe both sides of the boundary. Pin at least one real success and one relevant real error, assert domain semantics rather than only status/shape, and exercise stateful setup/cleanup/idempotency where writes are involved.
  • Verification needs provenance. A green claim names the independent evaluator and points to durable evidence when available (harness run, CI URL, review artifact); implementer self-report is not independent verification.

🚨 RAISE COVERAGE BEFORE MUTATING

Before any code-changing task on an existing module, that module's mix test.json --cover percentage must be at the target tier:

  • ≥80% for standard business logic
  • ≥95% for critical business logic (signing, money handling, cryptographic operations, low-level encoders, security-sensitive parsers)

If below tier, raise coverage first — write the missing tests, confirm the gate passes, then implement the change. The new tests are part of the task, not a follow-up.

Scope — code-changing mutations only. Exempt:

  • Doc-only edits (@doc, @moduledoc, inline comments, README, CHANGELOG)
  • Formatting, whitespace, alias reordering, autoformat-driven changes
  • Pure renames (variable, function, module — no behavior change)
  • Typo fixes in strings, log messages, error messages

The gate is a "do I have a safety net before I touch this?" check; writing the missing tests also surfaces the module's actual contract.

How to apply:

  1. Run mix test.json --cover --quiet --output /tmp/cov.json (or --cover-threshold 80 for a hard exit).

  2. Inspect the touched module's percentage: jq '.coverage.modules[] | select(.module == "MyApp.Foo")' /tmp/cov.json.

  3. If below tier, write tests for the uncovered lines until the gate passes — even if those lines aren't the ones you came to change.
  4. Then implement the original mutation.

Tier classification: "critical business logic" is project-defined. When in doubt, treat anything that handles money, signs/verifies, encodes/decodes wire formats, or enforces authorization as critical (95%). Plain data transforms, UI glue, and reporting code are standard (80%).

🚨 NEVER HIDE TEST FAILURES

TESTS THAT HIDE ERRORS ARE WORSE THAN NO TESTS AT ALL. A test that silently passes on errors is lying and ships the bug it was meant to catch.

The anti-pattern in all its forms — {:error, _} -> assert true, a catch-all {:error, _} -> :ok, or IO.puts(...) then assert true: any clause that makes every outcome pass. The fix is always an explicit flunk on the unexpected:

case result do
  {:ok, data} -> assert is_map(data)
  {:error, :insufficient_balance} -> :ok          # this specific error is expected
  {:error, other} -> flunk("Unexpected error: #{inspect(other)}")
end

THE RULE: if you don't know what error to expect, DON'T write the test yet — explore via Tidewave first, then assert. A test must FAIL when the code is wrong.

Integration tests — never skip silently on missing credentials. A suite reporting "0 failures" that ran 0 tests is lying. Don't :skip in setup; let the test run and flunk() at the top with a multi-line message listing the missing env vars, the exact export commands, and the URL to get them.

🚨 FIX HOOK-FLAGGED ISSUES ON FILES YOU TOUCH

When our hooks flag issues on files you touched, just fix them — including pre-existing flags unrelated to your change. Don't plan around it, don't ask permission, don't burn tokens discussing whether to. Hook fires → fix → re-run → stage.

Applies to every hook-driven check (credo, format, dialyzer, doctor, sobelow, ex_dna, etc.). Scope is only the files your change touched — not the whole project. User pre-approves the broader scope so each fix doesn't need a clarifying question; debt accumulates across sessions otherwise, and a touched file ending dirtier than baseline makes the next session noisier.

How to apply:

  • Pre-existing flags in your touched file count too: alias ordering, unused vars, refactor opportunities, TODO: formatting.
  • Generated files → fix the generator, not the output.
  • Don't move the fix to ROADMAP or a follow-up task. It happens in this commit.
  • Don't manually re-run a check the hook just ran on the same files. Act on the hook output directly — re-running mix test.json / mix credo / mix dialyzer.json / mix sobelow / mix precommit on the file set the hook already graded is duplicated work. Full-suite re-runs earn their cost only before a PR/merge, after mix deps.get or a branch switch, or when the user asks. See ~/.claude/CLAUDE.md § "Don't Re-Run Hook-Driven Checks on the Same Files" for the host-specific rule.

🚨 READ TO THE ANSWER — DON'T USE THE RUNNER AS AN ORACLE

Reason to the fix by reading code; run once to CONFIRM — don't run to DISCOVER. The failure mode: change → run suite → read one failure → fix one thing → run again, N times, each cycle paying the compile tax for a problem one read surfaces whole.

  • Read the code path before the test that exercises it — front-load the model, don't learn the function's shape from a failing assertion three fixes later.
  • Treat a failure as a SURVEY, not a single fix — enumerate every plausible cause from the output + one read, fix them in a batch, run once.
  • Verify handoffs/summaries against ground truth — a compaction summary or another session's "X is already wired" is a hypothesis; grep the load-bearing claim before acting on it.
  • Trust the hooks — per-edit checks already graded the file; re-running is wasted cycles.
  • Under a flaky terminal, go sequential-and-simple — one command → write to a file → Read it; no parallel batches of dependent calls, one early failure cancels the round.

🚨 FLAKY TESTS & TEST-RUN TOKEN ECONOMY

Elixir suites are non-deterministic at the edges (async / GenServer / Port / LiveView / supervision), and mix test is the biggest time/token sink in a session. Four disciplines:

  • A small red count is a flaky HYPOTHESIS, not a regression — until confirmed. 1–2 failures out of hundreds, in a file your diff didn't touch → suspect flake. Re-run ONLY that test in isolation (mix test.json <file>:<line> or --failed): passes alone → flaky, proceed; fails deterministically → real, fix it. One isolated re-run is the whole investigation — never repair-loop or block a merge on an unconfirmed flake.
  • NEVER Process.sleep to "fix" a flake. Sleeps mask the race, slow every future run, and still ship it (passing most of the time is the same lie as hiding a failure). Synchronize instead: assert_receive/refute_receive with a timeout, Process.monitor + assert_receive {:DOWN, …}, start_supervised!, or poll-until-condition.
  • Don't re-run a full suite to grade already-graded code. Per-edit hooks already ran test.json on touched files; a harness run already graded the stack green. A disjoint cherry-pick / clean merge of verified code needs no precommit.full re-run. Full suite only via a non-graded path — manual editor edits, a rebase with overlapping hunks, a branch switch, after mix deps.get.
  • Bound test output — never let coverage hit context. mix test.json --cover dumps the entire per-module JSON (tens–hundreds of KB). Always --output /tmp/cov.json + jq; triage with --max-failures 1 / --failed / a single file:line; drop --cover if you only need pass/fail.

🛑 MINIMALIST APPROACH FIRST

Do exactly what is asked — nothing more, nothing less.

  • NO proactive features or improvements unless explicitly requested
  • NO additional error handling beyond what's needed
  • NO extra validation, refactoring, or documentation files
  • ALWAYS ask before adding anything not explicitly mentioned
  • IF UNCLEAR: Ask "Should I also do X?" before proceeding

BUT: Minimalism Is Not Incomplete Work

"Start minimal" means no EXTRA features — not skipping items the task implies.

When a task says "define unified data structs," the scope is ALL structs the system needs, not "the 7 I can think of." When a source of truth exists (e.g., method_defs/0 listing 241 methods, each implying a return type), audit it — don't cherry-pick.

The pattern to avoid:

  1. Task says "build X for all Y"
  2. Claude scopes to "build X for the obvious Y" (filtering/cherry-picking)
  3. Later session discovers the gap and adds a fix-up task
  4. The fix-up task does what should have been done originally

How to catch it:

  • If the task mentions "all," audit the source of truth — don't rely on what comes to mind
  • If a data source defines N items, process N items (or explain why some are excluded)
  • If you're writing "for now we'll just do these 7" without being asked to limit scope — STOP. That's scoping out, not starting minimal.

Minimalism guards against: adding caching when nobody asked, building admin UIs "just in case," over-abstracting simple code.

Minimalism does NOT mean: skipping half the items in an enumerable set, cherry-picking "common" cases from a known complete list, or deferring clearly-implied work to future tasks.

🚨 NO PSEUDO-RIGOROUS HEDGING

Don't gate user-requested work behind invented "evidence requirements" you cannot satisfy.

You have no consumer telemetry. No usage counts. No signal about whether a feature will be called 12 times or 1200 times. So phrases like "demand for this is unproven", "we should wait until N consumers ask for this", "is this widely needed?", "only worth doing if a Nth+ use case is imminent" are risk-aversion theater, not analysis. They sound rigorous; they're hedging.

  • In single-developer codebases or focused teams, the developer IS the demand signal. They asked. That's the data point.
  • "Wait for usage data" is a corporate-flavored instinct that doesn't apply to small teams. There's no telemetry pipeline; there's the user in front of you.
  • It gaslights the user: their request is reframed as "unproven need" requiring further validation. They have to argue for what they already asked for.

Distinguish from minimalism (the section above):

  • Minimalism = don't add features the user didn't ask for.
  • This rule = don't refuse / defer features the user did ask for by inventing evidence requirements.

Distinguish from dependency-gating (the legitimate "wait"): parking work behind a named technical / legal / market-scope trigger with a concrete unblock path — a missing dep, an unactivated market, an additive change that's migration-cheap to add later — is NOT hedging. Hedging invents demand evidence you can't get ("wait until someone wants it"); dependency-gating cites a structural fact ("park until market MY activates — it's an additive @by_country member, so deferring forecloses nothing"). The STOP-list below targets the former, not the latter. Build-now pressure is for foreclosing decisions (annoying/migration-heavy to reverse — e.g. a geo dimension threaded through schema); an additive change carries no such pressure, so "build it now because one instance happens to be live" is overfit, not rigor. Reflexively reaching for build-now to avoid looking like you're hedging is the same theater inverted.

Failure-mode test — if you're about to write any of these, STOP:

  • "Demand for X is unproven"
  • "We should wait until..." (unless it names a concrete technical/legal/market-scope trigger with an unblock path — that's dependency-gating, not hedging)
  • "Is this widely needed?"
  • "Only worth doing if a Nth+ case is imminent"
  • "Bet on usage data before building"

You don't have data either way. The honest framing is: "I don't know if you'll use this 12 more times — that's your call."

What to do instead:

  • Name the actual technical risks (e.g., "the macro might grow more knobs than the duplication it removes," "this couples us to an upstream that breaks every release," "the test surface explodes at N+1 cases"). Those are real costs you can reason about.
  • Cite concrete precedents when scoring complexity (see development-philosophy.md "Cite Ecosystem Precedents Before Crying Complexity"). Generic "this could grow" without naming a specific failure pattern is the same hedging by another name.
  • If the task genuinely scores low on benefit/usefulness, score it that way honestly — don't smuggle a demand-speculation into the U/B numbers and pretend it came from analysis.

Scope extends to task body fields and scoring justifications, not just live responses. Same hedge phrases written into a task's body to justify B/U — "table-stakes", "increasingly expected", "now standard", "buyers expect", "competitors are starting to", "modern apps all do" — inflate the score the same way they inflate a response. Required instead: a concrete named reason — the user asked for it (the developer IS the demand signal), a named technical/legal trigger, a named competitor lever — OR an honest low score. Enforced at task-creation time by task-writing.md § Pre-Creation Gate (question 4).

Git Commit / Push / PR-Create — Allowed by Default

Committing, pushing, and opening PRs are normal parts of the work — do them without asking when the task calls for it (the agent-gate / auto-land workflow, worktree branches, and shared default branches alike). Announce the action in one line, then take it; the diff and push are the recap.

The only residual caution is the general one for any hard-to-reverse action: rewriting already-pushed history (force-push, amend/rebase of shared commits) can destroy others' work, so confirm before doing that on a shared branch — not because commits need permission, but because history-rewrite is irreversible.

🚨 STAGE PATH-SCOPED — THE WORKING TREE IS SHARED, YOU WORK IN PARALLEL

Never assume the working tree or index holds only your changes. Unrelated WIP sits in the tree, the index may already hold files another session git added, and an auto-land harness is a second committer. A blanket stage sweeps all of it into your commit.

  • NEVER git add -A / git add . / git commit -a. Stage explicitly: git add <path> …, or commit path-scoped: git commit <path> …. The commit then carries exactly the paths you name, regardless of what else is dirty or staged.
  • Verify the staged set before every commit — git diff --cached --name-only. If a path you didn't touch is there, it's someone else's; don't commit it.
  • A pre-commit hook tripping on a file you didn't touch means foreign WIP is dirty, not that you must fix it. Path-scoped-stash ONLY the foreign paths (git stash push -- <their-paths>), make your clean commit, git stash pop, then re-stage whatever was staged before so the other session's index is exactly as you found it. Never format, fix, or commit work that isn't yours to clear a hook.
  • Untracked dirs/files you didn't create: leave them — don't -u-stash or add them.

The failure mode this guards: you path-scope your commit correctly but git add -A first, or you stash -u to clear a hook and bury another session's staged work. Both corrupt parallel work silently.

🚨 NEVER BROADCAST AN UNPATCHED VULNERABILITY IN A COMMITTED FILE

A committed file is a public file — roadmap/tasks.toml, ROADMAP.md, CHANGELOG.md, code comments, and commit messages all ride to a repo that is often public (and is permanent in git history even if the repo is private today). Exploit-actionable detail for a vulnerability that is not yet BOTH fixed AND publicly disclosed must never go into one. A roadmap task that names the attack mechanism, the precise trigger value, a "this drains the wallet / leaks the key" walkthrough, or an unpublished GHSA/CVE id is a zero-day tip sheet you published yourself — handing every reader a working exploit for the entire window between filing and fixing.

The rule:

  • Open + undisclosed vuln → the detail stays OUT of git. Track it where the scanners and reporters already live: GitHub Security Advisories (private draft), a private issue, or a local/encrypted note. Not the public roadmap, not a TODO:, not the commit body.
  • Fixed AND advisory published → fine to reference (the hole is already public knowledge; describing the fix helps consumers patch). The gate is both, not either.
  • You still need to schedule the work? File the rmap task with a sanitized body — only what's needed to prioritize and route it ("harden Tempo fee-payer gas bounds — see private advisory <id>"), never the mechanism, trigger values, or PoC. The exploit recipe lives in the private advisory the task references by id.
  • During an embargo window, commit messages and CHANGELOG describe the shape of the fix, not the hole it closes, until disclosure day.

How to actually report, track, and disclose — the standing protocol for every repo:

  • Inbound reports land where you must actively look. Privately-reported vulns (GitHub Private Vulnerability Reporting) appear ONLY in the repo's Security → Advisories tab (gh api repos/<org>/<repo>/security-advisories) — NOT in Dependabot, code/secret-scanning alerts, or the notifications inbox. A security sweep that queries the four scanning endpoints but skips security-advisories misses every human-reported zero-day. Always query it; act on triage (new, unreviewed) and draft (in-progress) states.
  • Open vulns — inbound or self-discovered — are tracked in a private draft GitHub Security Advisory, one per issue. Full detail (mechanism, precise trigger, affected version range, the fix to port, PoC) lives there and only there. Create with gh api repos/<org>/<repo>/security-advisories -X POST (draft state); the required vulnerabilities[] array names the package ecosystem + name + vulnerable_version_range. This is the single channel — never a committed file.
  • Public artifacts carry only the reassuring posture. A security/parity ledger, roadmap, or CHANGELOG shows only ✓ closed / confirmed-fixed and 📋 tracked-as-work rows; open-gap detail appears at most as a generic count ("N open items tracked privately per SECURITY.md"). A public list advertises what you defend against — never an enumerated map of your unpatched weaknesses.
  • Coordinated disclosure on fix: ship the patch → cut the release → publish the advisory naming the patched version, same day (SECURITY.md governs the timeline). Once fixed-and-published, the previously-private detail describes a closed vuln — fine to reference, and helps consumers patch. The window to minimize is filed → fixed; close it with fix-speed, not with scrubbing.
  • A forward-only watcher (cron / routine / audit) obeys the same split: parity-confirmed → ✓ public row; genuine open gap → private draft advisory, never a public task or ledger row.

Failure mode this prevents: filing a detailed "here's the CVE and exactly how to trigger it" task into a committed public roadmap — the backlog becomes an attacker's to-do list, ranked by how long you've left each hole open. Adding this rule is prevention; a vuln already committed is already leaked — redact it now (and treat git history as compromised: rotate/patch on the assumption it was read), don't just delete it going forward.

Shell Safety

rm (including rm -rf) is permitted — the hook allows it; the old blanket ban caused more friction than it prevented. One habit, not a gate: before an irreversible delete, glance at the target — confirm the path is what you intend (no unexpanded $VAR, no wildcard catching more than you mean, not a path you didn't create or weren't asked to remove). git rm for tracked files keeps the removal in the diff. (Destructive dependency / build commands — mix deps.clean, rm -rf _build — stay consent-gated below, for slow-recovery reasons, not safety.)

🚨 NEVER RUN DESTRUCTIVE DEPENDENCY COMMANDS

Never run these without explicit user consent:

  • ❌ mix deps.clean / mix deps.clean --all — deletes compiled deps; slow recovery
  • ❌ mix deps.unlock --all — unlocks all versions
  • ❌ rm -rf _build or rm -rf deps — nukes build artifacts
  • ❌ mix clean — removes compiled app files

What to do instead:

  • Compile error → just retry mix compile or mix test
  • Specific dep issue → mix deps.compile <dep_name> --force
  • Most "corrupt cache" issues are transient glitches

Ask before running any destructive command.

🚨 NO SCOPE-SEQUENCING QUALIFIERS IN DURABLE ARTIFACTS

Never write positioning/sequencing qualifiers — "X first", "starting with X", "initially", "for now", "MVP: X" — into durable artifacts: repo descriptions, READMEs, moduledocs, code comments, config comments, commit messages, vision one-liners. These phrases metastasize (every future session copies them into new files and defends them as intent) and become practically unremovable. Scope sequencing lives in ONE place: the roadmap (milestones, task bodies, out_of_scope). Everywhere else, describe what the system IS, not what it will be next: "Coverage: Robinhood Chain tokenized equities" states a fact; "starting with Robinhood Chain" bakes a forecast into the artifact.

🚨 Integrity and Accuracy

Never fabricate information, experience, or data. When providing technical guidance:

  • Honest about sources: distinguish codebase observations, general knowledge, best practices, and speculation. Never claim production experience you don't have or invent metrics/timelines/stats.
  • No false authority: don't claim "we learned" without repo evidence; don't state "after X years in production" without evidence; use "typically/often/may/could" when uncertain.
  • Document uncertainty: identify what you don't know, suggest validation paths, provide ranges over false precision.
  • Trace sources: "Based on the code in file.ex...", "According to docs/FILE.md...", "Common practice in Elixir...", "This suggests..."

False technical claims cascade into bad architectural decisions, wasted resources, and damaged trust.

🚨 RESEARCH BEFORE ASSERTING ON NICHE TECHNICAL CLAIMS

When the question lives outside reliable training coverage, research proactively — without being asked. The failure mode is asserting from training-bias confidence on specs/protocols/niche APIs the model never deeply absorbed. Codex fetches reference implementations to verify; Claude defaults to "answer from memory." Close the gap.

Research (WebFetch a known URL, WebSearch to find one) when the topic is:

  • Wire formats / encodings — RLP, ABI, SSZ, Protobuf, BLS, BIP-32/39/44, EIP-712, CBOR, ASN.1/DER. Fetch the spec or a reference impl before claiming byte order, length-prefix, padding, or canonical form.
  • Protocol details — EIPs, RFCs, JSON-RPC shapes/error codes, opcode gas, exchange API quirks (signature canonicalization, error envelopes, rate-limit headers).
  • Niche / recent library APIs — guessing signatures, return shapes, version-pinned breaking changes. If you'd write # probably something like, go fetch the docs.
  • Cross-implementation edge cases — "what does X do when Y is malformed?" → check ≥2 reference impls; one impl's behavior can be a bug, agreement across two is the spec in practice.

Don't research (use memory): pure Elixir/OTP, stdlib, mainstream Phoenix/LiveView/Ecto/Ash, generic REST/HTTP/JSON/SQL/shell, anything already in the codebase / hex docs pulled this session / an imported CLAUDE.md.

How to apply: prefer WebFetch when the canonical URL is known (the EIP/RFC/hex doc/reference-impl path), WebSearch to find one; cite what you fetched — the citation is part of the answer, name both impls for cross-checks. If a fetch fails or is ambiguous, say so and lower confidence — don't fall back to "well, I think…" silently.

🚨 NO EVASION — SIT WITH THE HARD THING

When you hit something difficult, do NOT optimize for "appearing productive" by moving to easier work. The most common failure mode: hit a wall → silently move on → user discovers the gap later.

Evasion Patterns (don't use without explicit user approval)

Task abandonment:

  • "let's move on to", "we can defer this", "skip this for now"
  • "let's come back to this later", "we can revisit this", "let's table this"

Scope reduction without asking:

  • "to keep things simple, I'll skip", "for brevity, I won't"
  • "that's out of scope", "not strictly necessary"

False completion:

  • "that should be enough", "the rest is straightforward"
  • "I'll leave the rest as an exercise", "the pattern is clear enough"

Deflection to user:

  • "you might want to", "you could manually", "you'll need to handle"
  • (Sometimes legitimate — but often evasion disguised as helpfulness)

What To Do Instead

  1. Stay with it. If it's hard, say "this is hard because X" — don't silently move on
  2. Flag blockers explicitly. "I'm blocked on X because Y. Options: A, B, or C."
  3. Ask before deferring. "This is taking longer than expected. Should I continue or switch?"
  4. Never write workarounds silently. If tempted to add a fallback/default/nil-guard for missing data, ask: should this come from upstream? If yes, STOP and report it
  5. Incomplete work gets a TODO. If you must move on, leave a tracked TODO — not a silent gap

Project Overview

ZenWebsocket is a robust WebSocket client library for Elixir, specifically designed for financial APIs (particularly Deribit cryptocurrency trading). Built on Gun transport with 8 foundation modules, enhanced with critical financial infrastructure.

Financial Development Principle: Start simple, add complexity only when necessary based on real data.

Project-Specific Commands

# Code Quality (use JSON output for AI-friendly results)
mix test.json                                  # Run tests (see logs/warnings)
mix test.json --quiet                          # Run tests (clean JSON only)
mix test.json --quiet --failed --first-failure # Iterate on failures
mix dialyzer.json --quiet                      # Type checking
mix credo --strict --format json               # Static analysis
mix security                                   # Sobelow security scan

# Testing (integration tests excluded by default)
mix test.json --quiet --summary-only   # Quick health check
mix test --include integration         # Include integration tests
mix test.api              # Real API integration tests
mix test.api --deribit    # Deribit-specific tests
mix test.performance      # Performance/stress testing

Toolchain & check commands

Self-contained so it survives into AGENTS.md on regen — cross-family reviewers (codex / cursor / grok) read AGENTS.md, not the Claude skill set.

  • Canonical gate: mix precommit.full (alias mix ci) — the comprehensive pass the harness reviewer's check_command runs and what GitHub CI (.github/workflows/harness.yml) invokes directly. Fast local loop: mix precommit (skips the cold-PLT dialyzer + deps audit).
  • mix precommit.full runs, in order: compile --warnings-as-errors, format --check-formatted, credo --strict (ignoring TODO/FIXME tags), doctor --raise, ex_dna --max-clones 0 (zero-clone budget), reach.check --arch --smells (policy in .reach.exs), sobelow --skip, deps.audit.gated, test.json --cover --cover-threshold 58 --exclude integration (MIX_ENV=test), dialyzer (forced MIX_ENV=dev — see below), agents.check.
  • The coverage floor is a measured ratchet, not an aspiration. 58 is the non-integration coverage measured 2026-08-01, rounded down; the previous 80 had never been met by any run and so gated nothing. Raise it in lockstep with real coverage; never pad it.
  • mix test.json (ex_unit_json) and mix dialyzer.json (dialyzer_json) emit JSON by design — this is NOT a build failure. Parse the JSON for real failures; never flag the envelope itself. Plain mix dialyzer is the authoritative dialyzer check when the JSON encoder can't serialize a warning shape.
  • The gate's dialyzer step forces MIX_ENV=dev, not :test. Under :test, the test-only mock-server stack (cowboy, plug_cowboy, websock, x509, temp, stream_data) joins this repo's plt_add_deps: :apps_direct analyzed set and produces false unknown_function warnings against the OOM-tuned PLT (see defp dialyzer in mix.exs). preferred_envs in def cli is ignored inside alias steps, so the dev override is an explicit cmd env MIX_ENV=dev mix dialyzer.
  • reach.check --arch --smells gates from .reach.exs (smells: [strict: true]). Smell findings must be fixed for real, never added to an ignore list.
  • deps.audit.gated proves the local mix_audit advisory mirror is fresh (bin/advisory-freshness.sh in onchain-stack) before running mix deps.audit --ignore-file .mix_audit_ignore — mix_audit discards its own sync exit status (mirego/mix_audit#61), so a frozen mirror would otherwise report a false "No vulnerabilities found." .mix_audit_ignore carries exactly one verified false positive (GHSA-w4f7-4cxr-rv3c on gun); do not add other advisory ids there — a real finding gets reported, never suppressed.

Documentation

Use the existing docs instead of re-explaining patterns from scratch:

  • README.md for package overview and top-level discovery
  • AGENTS.md for contributor workflow and verification expectations
  • docs/guides/building_adapters.md for adapter patterns
  • docs/guides/performance_tuning.md for telemetry and tuning
  • docs/guides/troubleshooting_reconnection.md for reconnect diagnostics
  • docs/guides/deployment_considerations.md for production deployment trade-offs

Architecture

Module Structure

lib/zen_websocket/
├── client.ex              # Main client interface (5 public functions)
├── config.ex              # Configuration struct and validation
├── frame.ex               # WebSocket frame encoding/decoding
├── connection_registry.ex # ETS-based connection tracking
├── reconnection.ex        # Exponential backoff retry logic
├── message_handler.ex     # Message parsing and routing
├── error_handler.ex       # Error categorization and recovery
├── json_rpc.ex           # JSON-RPC 2.0 protocol support
├── correlation_manager.ex # Request/response correlation
├── rate_limiter.ex        # API rate limit management
└── examples/
    └── deribit_adapter.ex # Deribit platform integration

Public API (5 Functions)

ZenWebsocket.Client.connect(url, opts)
ZenWebsocket.Client.send_message(client, message)
ZenWebsocket.Client.close(client)
ZenWebsocket.Client.subscribe(client, channels)
ZenWebsocket.Client.get_state(client)

Project Constraints

  • Maximum 5 functions per module (new modules)
  • Maximum 15 lines per function
  • Direct Gun API usage - no wrapper layers
  • Real API testing only - zero mocks

Example Code Policy

Non-negotiable: All examples must be written and tested in lib/ and test/ first, with full validation (compile, Dialyzer, Credo, tests). After validation:

  • Small patterns (< 50 lines): Stay in lib/zen_websocket/examples/
  • Large applications: Move to examples/<name>/ as separate mix project

See AGENTS.md for full policy details.

Configuration

Environment Setup

export DERIBIT_CLIENT_ID="your_client_id"
export DERIBIT_CLIENT_SECRET="your_client_secret"

ZenWebsocket.Config Options

  • url - WebSocket endpoint URL
  • headers - Connection headers
  • timeout - Connection timeout (default: 5000ms)
  • retry_count - Maximum retry attempts (default: 3)
  • retry_delay - Initial retry delay (default: 1000ms)
  • heartbeat_interval - Ping interval (default: 30000ms)

Testing Strategy

Test Coverage Requirements

When modifying any module, ensure it has both:

  1. Unit tests - Pure function logic, no network/I/O, fast execution
  2. Integration tests - Real connections via MockWebSockServer or external APIs

If either is missing, create them before completing the task.

Test Tagging

  • :integration - Tests using MockWebSockServer or external services
  • :external_network - Tests requiring internet (Deribit testnet, etc.)
  • Default mix test excludes these for fast feedback

Real API Testing Policy

NO MOCKS ALLOWED - Only real API testing:

  • test.deribit.com for Deribit integration
  • Local mock servers using MockWebSockServer
  • Real network conditions and error scenarios

Rationale: Financial software requires testing against real conditions. Mocks hide edge cases that cause financial losses.

Narrow exception: opaque transport message shapes

Test doubles are permitted for Gun transport message tuples only — the four shapes :gun_upgrade, :gun_ws, :gun_down, :gun_error. This is a single, fenced carve-out; all other forms of mocking remain prohibited.

What is permitted:

  • Constructing the four Gun tuple shapes for unit-level tests of pure functions that consume them (e.g., MessageHandler.handle_message/2)
  • Fixtures must use real pid() values (from self() or spawn) and real reference() values (from make_ref/0). No fake opaque values.

Why this is not a real mock: Gun's pid and stream_ref are opaque BEAM primitives with no public contract. There is no behavior for a fixture to drift against — only a tuple shape. Shape-only fixtures enable property-based testing of routing totality without stubbing any behavior.

What is NOT newly allowed (explicit, to prevent drift):

  • API response fixtures (Deribit, Binance, any exchange)
  • Authentication flow simulation
  • Exchange behavior simulation (subscription acks, order responses, heartbeats)
  • Any fixture with semantic content beyond the raw transport-frame shape
  • Fixtures for anything that is not one of the four Gun tuple shapes

Source of truth unchanged: MockWebSockServer (real cowboy/websock stack) and real-API tests remain the source of truth for all business logic. Any test touching Client GenServer state, reconnection, subscription semantics, or exchange behavior continues to require MockWebSockServer or a real endpoint.

Test Support Modules

  • MockWebSockServer - Controlled WebSocket server
  • CertificateHelper - TLS certificate generation
  • NetworkSimulator - Network condition simulation
  • TestEnvironment - Environment management

WebSocket Connection Architecture

Connection Model

Reconnection Pattern

{:ok, client} = ZenWebsocket.Client.connect(url, [
  timeout: 5000,
  retry_count: 3,
  retry_delay: 1000,
  heartbeat_interval: 30000
])

Platform Integration

Deribit Adapter

Located in lib/zen_websocket/examples/deribit_adapter.ex:

  • Authentication flow
  • Subscription management
  • Heartbeat/test_request handling
  • JSON-RPC 2.0 formatting
  • Cancel-on-disconnect protection

Supervised Pattern (production):

connect_opts = [
  reconnect_on_error: false,  # Adapter handles reconnection
  heartbeat_config: %{...}
]

Standalone Pattern (simple use):

{:ok, client} = Client.connect(url)  # reconnect_on_error: true (default)

Key Dependencies

Core Runtime

  • gun ~> 2.4 - HTTP/2 and WebSocket client (bound requires the GHSA-w4f7-4cxr-rv3c fix, not just permits it)
  • jason ~> 1.4 - JSON encoding/decoding
  • telemetry ~> 1.3 - Metrics and monitoring

Development

  • credo, dialyxir, sobelow, ex_doc, ex_dna (code duplication detection)

Testing

  • cowboy ~> 2.10, websock ~> 0.5, stream_data ~> 1.0, x509 ~> 0.8

Task Management

Roadmap

See roadmap.md for:

  • Current focus and active tasks
  • Prioritized task list with D/B scoring
  • Completed work history

Task ID Format

Use WNX#### format:

  • Core: WNX0001-WNX0099
  • Features: WNX0100-WNX0199
  • Docs: WNX0200-WNX0299
  • Tests: WNX0300-WNX0399

Task Tracking

Tasks tracked in roadmap.md with status markers:

  • ⬜ Pending
  • 🔄 In progress
  • ✅ Complete

Priority uses D/B scoring (Difficulty/Benefit ratio).

WebSocket-Specific Requirements

  • All connection tasks must include real API testing
  • Platform integration tasks reference Deribit adapter patterns
  • Frame handling tasks include malformed data testing
  • Reconnection tasks test real network interruptions