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zipnative-mcp

zipnative-mcp

MCP server for ZIP archives — deterministic creation, inspection and listing without extracting, random-access entry reads, secure-by-default extraction, one-call verification, forward scanning of truncated streams, incremental modification without recompression, CRC-32 and raw-DEFLATE inflation — 13 tools on the zipnative engine (zero-dependency, ISO/IEC 21320-1 conformance validated in CI), for Claude Desktop, Cursor, ChatGPT and any MCP client.

npm version npm downloads Node version License: MIT CI ISO 21320-1 · veraZIP MCP zipnative TypeScript OpenSSF Scorecard CodeQL


✨ Features

zipnative-mcp exposes 13 tools to any MCP host:

Tool

What it does

Read-only

inspect_zip

ONE-call archive report: sizes, entry / file / directory counts, Zip64, comment, compressed vs uncompressed totals, per-method counts, encrypted / symlink / data-descriptor / Zip64 / cp437 / duplicate / unsafe-name counts, date range, a determinism verdict (the structural one: epoch timestamps + canonical order + UTF-8 flags) and every engine diagnostic. Opens eagerly: every entry's real extent is checked up front — overlapping entries, entries reaching into the central directory or past EOF, Zip64 spoofing — and refused with their ZIP_* code (a method / CRC / size divergence between central and local headers is caught by verify_zip and on read, not here). check: […] + assert: {…} turn it into a CI gate.

list_zip_entries

Paged central-directory inventory, nothing decompressed — every entry as a full row (sizes, CRC-32, method, timestamp, flags, Unix mode, symlink, Zip64, offsets, extra fields, the sanitized path an extraction would use, raw name bytes). filter by names / prefix / glob, offset + limit (200 default, 2000 max).

read_zip_entry

ONE entry by name or index without extracting: decompressed content as base64 or UTF-8 text (CRC-verified), a byte range through the chunked stream, the raw compressed payload (mode: 'raw'), or a non-throwing integrity check (mode: 'verify').

verify_zip

Deep verification in one call — the engine's verifyZip report verbatim: structure, every entry's CRC-32 / size / local-header agreement, encrypted entries honestly skipped — while an entry whose method has no codec here (anything but 0 store / 8 deflate) is reported failed, not skipped. Never isError for an archive problem: branch on ok and error.code.

extract_zip

Secure by default: zip-slip / device names, symlinks, duplicate paths, declared-size and ratio bombs, overlapping entries and central/local divergence refused with frozen ZIP_* codes; relaxations are explicit named inputs that skip, never emit. Inline files (includeData: false = dry run — it opens eagerly and refuses an overlapping, offset-into-CD or Zip64-spoofed archive before returning any plan) or streamed into the sandbox with resource links.

scan_zip_forward

Walk local headers in stream order with bounded memory — the only tool that works on a truncated download or a cut / unseekable stream that starts at a local header, and the only one whose result is NOT authoritative (trust: 'local-headers-only'). tolerateTruncation: true returns the partial inventory plus the error. It cannot skip an SFX / prepended prefix and refuses one (ZIP_SIGNATURE_MISMATCH): inspect_zip reports it (prependedData, ZIP_PREPENDED_DATA) and modify_zip mode: 'compact' drops it.

sanitize_entry_paths

The engine's single traversal gate over a list of names: the safe /-relative form each maps to, or null with the rule that fired (traversal, absolute, drive, UNC, NUL, ADS, device name). No archive needed.

create_zip

Write a ZIP from inline text / base64 / sandbox files (up to 100 000 entries — Zip64 auto-promotes past 65 535). Reproducible on one runtime by default (canonical order, DOS-epoch timestamps, UTF-8 names); compression.deterministic: true for identical bytes on every runtime — summary.deterministic is true ONLY then (a default call reports false with deflateTier: 'node-zlib'); store / deflate at archive or entry level; order: 'insertion' for EPUB / JAR; comments, Unix modes, extra fields; streamed sources; the worker pool (parallel, byte-identical); includeSha256 proofs in base64 and file mode.

modify_zip

add / replace / remove / rename / setComment without recompressing anything. mode: 'append' keeps the original bytes verbatim (removed content stays recoverable — data remanence, said loudly); mode: 'compact' rewrites canonically so it is truly gone.

compute_crc32

The ZIP checksum (IEEE 802.3 CRC-32, the engine's slice-by-8) of text, base64 or a sandbox file streamed in 1 MiB chunks; seed chains chunks, expect compares.

inflate_raw

Raw DEFLATE (RFC 1951) through the engine's resumable inflater with a mandatory maxOutput bound: exact bytesConsumed, trailing bytes as leftover. Feed it read_zip_entry mode: 'raw'.

describe_engine

Offline preflight: versions, deflate tiers, runtime codecs and workers, the engine's default limits, the operator ceilings, every server cap, sandbox / cache state, the 39 error codes and 11 diagnostic codes, the deliberately unexposed engine exports. network is always 'none'.

draft_governance_issue

Draft a governance-compliant GitHub issue locally for a human to review and submit — never submits, no network, no GitHub write path.

What every tool guarantees:

  • 🔐 Secure by default — every engine guard is on; a relaxation is an explicit, named input (rejectTraversal, rejectSymlinks, onDuplicate, limits) that skips, never emits an unsafe path or materialises a link. Overlaps, central/local divergence and Zip64 spoofing have no opt-out at all.

  • 🌐 No network, ever — the server has no network code path: no telemetry, no GitHub, no URL from any argument, no operator-configurable endpoint. The only filesystem boundary is ZIPNATIVE_MCP_OUTPUT_DIR.

  • 🔁 Reproducible by default, deterministic on requestcreate_zip emits canonical order, DOS-epoch timestamps and UTF-8 names unless you opt out, so the bytes are stable on one runtime; compression.deterministic: true pins the pure-TypeScript encoder for identical SHA-256 on every runtime and is the only setting under which summary.deterministic is true; inspect_zip.determinism is the separate structural verdict (epoch timestamps required); parallel is byte-identical.

  • 🧭 Frozen ZIP_* error codes, verbatim — the engine's 39-code vocabulary reaches you unchanged in _meta.error.code (with the entry name, the limit that fired, both CRCs, …), plus the wrapper's own 16 codes. Branch on the code, never on the message.

  • 🪙 Token-frugal projections — the read tools accept verbosity: 'summary' and fields: […]; produced archives are delivered once as an embedded resource block, never duplicated into structuredContent.

  • 📏 ISO/IEC 21320-1 conformance gate — every archive the tools write is validated clause by clause by an engine-independent validator (veraZIP) on Linux and Windows in CI and again before publish.

All archive-producing tools support two output modes:

  • base64 (default) — the archive is returned once as an embedded resource content block (a data:application/zip;base64,… URI); structuredContent carries { mode, sizeBytes, summary, diagnostics, diagnosticCounts }.

  • file — the archive is streamed into a sandboxed directory configured via ZIPNATIVE_MCP_OUTPUT_DIR (≤ 4 GiB, never overwritten) and the result carries a resource_link. File I/O is disabled unless this variable is set; absolute paths, traversal, non-container extensions and NUL bytes are all rejected, and the real path of every file read and of every parent written must stay inside the sandbox (a planted symlink or junction is SECURITY_VIOLATION on both sides). The same sandbox serves zipPath / sourcePath inputs, so a create_zip → modify_zip → verify_zip → extract_zip chain never re-sends the bytes.

Token-frugal reads. The read tools (inspect_zip, list_zip_entries, read_zip_entry, verify_zip, scan_zip_forward, sanitize_entry_paths, describe_engine) and extract_zip accept two optional inputs:

  • verbosity: 'summary' — a compact scalar-only verdict (drops the rows and payloads). E.g. verify_zip{ ok, error, entryCount, verifiedCount, failedCount, skippedCount, diagnosticCount }; inspect_zip keeps deterministic, canonicalLayout, checksPassed.

  • fields: ['a', 'b.c'] — projects the structured result to named dot-paths; composes after verbosity. Unmatched paths are omitted and reported in _meta.unmatchedFields (with _meta.availableFields).

Smallest "is this archive intact?" probe: { "zipBase64": "…", "verbosity": "summary", "fields": ["ok", "error", "failedCount"] } on verify_zip.

The server also ships seven MCP promptssecure_extraction, reproducible_archive, incremental_update, forensic_scan, verify_before_trust, governance_contract, draft_issue_workflow — and exposes every file in the sandbox as a zipnative://output/{+path} resource.

Why zipnative?

zipnative-mcp inherits every guarantee of the underlying engine:

  • Zero runtime dependencies in the engine — pure TypeScript, no native bindings, no eval; one API across Node ≥ 22, browsers, Deno, Bun and Workers (this server adds only the MCP SDK and zod: three runtime dependencies in total).

  • Safe by default — path traversal, symlinks, duplicate names, decompression bombs, overlapping entries, parser-differential smuggling and Zip64 spoofing are refused, not guessed at; every parser loop runs under a named, CWE-tagged, caller-configurable bound.

  • Random access and streaming — read one entry from a multi-gigabyte archive without touching the rest; iterate unseekable streams with bounded memory.

  • Deterministic — a written determinism contract: reproducible layout always, byte-stable per environment by default, and the same SHA-256 on every runtime under compression.deterministic: true.

  • Incremental modification — replace, remove, add or rename entries without recompressing the untouched 99 % (append-only), or compact for true deletion.

  • A frozen 39-code error vocabulary and verifyZip() — one call, a machine-readable report that never throws for archive problems.

  • The first open clause-by-clause ISO/IEC 21320-1:2015 validator, blocking in CI.

  • What it will NOT do: no encryption (read or write, in 1.x — ZipCrypto is broken), no other archive formats, no multi-disk archives, no archive repair, no filesystem I/O in the engine, no network access, ever.


🚀 Installation

# Run directly with npx (recommended for MCP clients)
npx -y zipnative-mcp

# Or install globally
npm install -g zipnative-mcp
zipnative-mcp

Requirements: Node.js ≥ 22.


⚙️ Configuration

Claude Desktop

Edit ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "zipnative": {
      "command": "npx",
      "args": ["-y", "zipnative-mcp"],
      "env": {
        "ZIPNATIVE_MCP_OUTPUT_DIR": "/Users/you/Documents/mcp-archives"
      }
    }
  }
}

Cursor / Continue / Zed / Windsurf / Cline / Roo Code

Any MCP-compatible client that supports stdio servers will work. Use the same command + args + env triple. Example for Cursor (~/.cursor/mcp.json):

{
  "mcpServers": {
    "zipnative": {
      "command": "npx",
      "args": ["-y", "zipnative-mcp"],
      "env": { "ZIPNATIVE_MCP_OUTPUT_DIR": "/Users/you/Documents/mcp-archives" }
    }
  }
}

Windsurf / Cline / Roo Code use the same shape inside their respective MCP config files.

VS Code

.vscode/mcp.json:

{
  "servers": {
    "zipnative": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "zipnative-mcp"],
      "env": { "ZIPNATIVE_MCP_OUTPUT_DIR": "${workspaceFolder}/.mcp-archives" }
    }
  }
}

🌐 Supported AI Ecosystem & Clients

zipnative-mcp is designed for MCP-native environments and works with clients that support MCP over stdio or Streamable HTTP: Claude Desktop, Claude Code, Cursor, Continue, Zed, Windsurf, Cline, Roo Code, VS Code, ChatGPT (Streamable HTTP), the MCP Inspector, and any client built on the MCP TypeScript / Python SDKs. Because the server never opens a socket of its own, it is also safe to run inside air-gapped or egress-restricted hosts.

🔌 MCP protocol compliance

The server is built on the MCP TypeScript SDK v2 (@modelcontextprotocol/server) and speaks MCP 2026-07-28:

  • Stateless servingserver/discover replaces the session handshake; every result carries resultType and the _meta serverInfo envelope. Over HTTP, 2026-07-28 clients send Mcp-Method / Mcp-Name headers with each POST /mcp.

  • Cache hintstools/list and prompts/list are public with a 24 h ttlMs, server/discover is public for 1 h, and resources/list / resources/templates/list / resources/read are private with ttlMs: 0 (sandbox files are per-host user data).

  • Protocol errorstools/call with an unknown tool name is a JSON-RPC error (-32602, [UNKNOWN_TOOL] Unknown tool: …) rather than an isError result, and an unknown resource URI is -32602 (Invalid params), as the specification requires; isError: true is reserved for execution failures.

  • Automatic legacy fallback — a client that opens with initialize is served through the SDK's legacy path on both stdio and HTTP for every revision the SDK negotiates: 2024-10-07, 2024-11-05, 2025-03-26, 2025-06-18 and 2025-11-25 (legacy) next to 2026-07-28 (modern). Nothing changes for existing hosts. tests/protocol-revisions.test.ts proves each legacy revision negotiates exactly that revision and serves the 13 tools; tests/stdio-modern.test.ts and tests/http-modern.test.ts prove the 2026-07-28 path on stdio and HTTP.

  • HTTPPOST /mcp only; GET / DELETE /mcp answer 405 (no SSE resumability; the server is stateless). Bound to 127.0.0.1 with a Host / Origin guard (foreign values → 403; the Origin port must equal the server port); ZIPNATIVE_MCP_HTTP_TOKEN adds an opt-in bearer-token gate (401 + WWW-Authenticate without it); bodies above 256 MiB → 413.

  • stdio — the SDK's 10 MiB default frame cap is raised to 256 MiB so multi-MiB base64 archives fit in one tools/call; as in every SDK release, a request sent before initialize is dropped without a reply on the legacy path.

  • Output schemas — every structuredContent validates against the tool's outputSchema (a 2026-07-28 MUST), including verbosity: 'summary' and fields projections: the read tools declare projectable schemas (all properties optional, additionalProperties: false kept). Input schemas carry no $schema keyword and no $ref by policy (some hosts forward inputSchema to function-calling APIs that reject unknown keywords). serverInfo carries websiteUrl; the resource template is zipnative://output/{+path}.

The tools/call payload (content, structuredContent, isError) is identical between the 2026-07-28 path and the legacy path; tests/http-modern.test.ts asserts it, and tests/schema-conformance.test.ts validates structuredContent with the SDK's JSON Schema 2020-12 validator.

Client

Transport

Protocol negotiated

Claude Desktop, Cursor, Continue, Zed, Windsurf, Cline

stdio

legacy initialize (2024-xx / 2025-xx) — unchanged

ChatGPT and other Streamable HTTP hosts

HTTP POST /mcp

legacy stateless streamable HTTP — unchanged

MCP 2026-07-28 clients (SDK v2 Client, current MCP Inspector)

stdio / HTTP

server/discover, cache hints, _meta envelope

Compatibility matrix — every negotiated revision, on both transports, with the test that proves it:

Revision

Era

stdio

HTTP POST /mcp

Proven by

2024-10-07

legacy initialize

tests/protocol-revisions.test.ts

2024-11-05

legacy initialize

tests/protocol-revisions.test.ts

2025-03-26

legacy initialize (JSON-RPC batches accepted over HTTP, refused on stdio)

tests/protocol-revisions.test.ts, tests/cli-stdio.test.ts, tests/http-modern.test.ts

2025-06-18

legacy initialize

tests/protocol-revisions.test.ts, tests/cli-stdio.test.ts, tests/http-modern.test.ts, tests/http-transport.test.ts

2025-11-25

legacy initialize

tests/protocol-revisions.test.ts, tests/cli-stdio.test.ts, tests/http-modern.test.ts, tests/autonomy.test.ts

2026-07-28

modern (server/discover, _meta envelope, cache hints)

✓ (+ bearer token)

tests/stdio-modern.test.ts, tests/http-modern.test.ts, tests/autonomy.test.ts

Autonomy proof. tests/autonomy.test.ts replays one scripted agent scenario (S0 handshake → S1 tools/list → S2 describe_engine → S3 create_zip file / base64 / parallel → S4 verify_zip → S5 inspect_zip checks → S6 list_zip_entries → S7 read_zip_entry / inflate_raw / compute_crc32 → S8 modify_zip append then compact → S9 extract_zip dry run then files → S10 resources/* → S11 scan_zip_forward → S12 hostile refusals → S13 ceilings → S14 protocol errors → S15 draft_governance_issue → S16 prompts/get → S17 clean shutdown) against the built dist/cli.js on four transports — stdio legacy, stdio modern, HTTP legacy, HTTP modern with ZIPNATIVE_MCP_HTTP_TOKEN — under a sandbox, a cache directory, ZIPNATIVE_MCP_MAX_ENTRIES=5000 and ZIPNATIVE_MCP_WORKERS=2, asserting no interaction, no unexpected isError, a code and a remedy on every refusal, a cache hit over the wire, a JSON-only stdout and a clean exit. To replay it by hand from Claude Code, Claude Desktop or the MCP Inspector, see docs/guides/LOCAL_TESTING.md § "Drive it from Claude Code / Claude Desktop / MCP Inspector" (the repository ships a ready .mcp.json).

Environment variables

Variable

Default

Meaning

ZIPNATIVE_MCP_OUTPUT_DIR

(unset)

Absolute path of the one sandbox directory: zipPath / sourcePath inputs are read from it, outputMode: 'file' / outputDir outputs are written under it (exclusive create — never overwritten). The real path of every file read and of every parent written must stay inside it: a symlink or junction planted in the sandbox is SECURITY_VIOLATION on zipPath / sourcePath / resources/read as much as on writes. Unset ⇒ every path input and file output is refused and the tools work on base64 only.

ZIPNATIVE_MCP_CACHE_DIR

(unset)

Opt-in persistent SHA-256-keyed result cache (1 h TTL, 256 MiB LRU, plaintext at rest; key namespaced by tool API + package + engine version). Never caches zipPath / sourcePath inputs, file output, defaultDate: 'now', parallel, describe_engine or draft_governance_issue; a hit carries _meta.cached: true.

ZIPNATIVE_MCP_PORT

(unset → stdio)

When set to a valid port (1–65535), serves Streamable HTTP on http://127.0.0.1:<port>/mcp instead of stdio. Loopback only, DNS-rebinding protection (foreign Host / Origin403), GET / DELETE → 405. No authentication unless ZIPNATIVE_MCP_HTTP_TOKEN is set — other local processes can reach the endpoint.

ZIPNATIVE_MCP_HTTP_TOKEN

(unset)

(secret) Opt-in bearer token for the HTTP transport (≥ 16 characters, no whitespace — a weaker value aborts startup). When set, every /mcp request must carry Authorization: Bearer <token>; otherwise 401 + WWW-Authenticate: Bearer realm="zipnative-mcp" (with error="invalid_token" only when credentials were sent — RFC 6750 §3.1). Compared constant-time, never logged.

ZIPNATIVE_MCP_MAX_UNCOMPRESSED_BYTES

8589934592 (8 GiB)

Operator ceiling for limits.maxEntryUncompressedSize and limits.maxTotalUncompressedSize. Integer ≥ 1024, read once at startup — an invalid value refuses to start. A per-call value above it is LIMIT_CEILING_EXCEEDED; a ceiling below the engine default tightens the default silently.

ZIPNATIVE_MCP_MAX_ENTRIES

100000

Operator ceiling for limits.maxEntries and scan_zip_forward maxEntries (whose default of 10 000 is clamped to the ceiling; only an explicit value above it is LIMIT_CEILING_EXCEEDED). Integer ≥ 1, read once at startup.

ZIPNATIVE_MCP_WORKERS

8

Operator ceiling for create_zip parallel.workers; with no explicit workers the engine default max(1, min(cores − 1, 8)) applies, bounded by this ceiling; 0 disables worker threads (compression stays on the calling thread). Integer ≥ 0, read once at startup.


🛠 Tool reference

Every archive-consuming tool takes exactly one of zipBase64 (the raw archive as base64 exactly once; a data:…;base64, prefix is tolerated; decoded ≤ 128 MiB) or zipPath (a relative path inside the sandbox; container extensions only — .zip .jar .war .ear .docx .xlsx .pptx .odt .ods .odp .epub .vsix .nupkg .whl .apk .ipa .xpi .crx .kmz; ≤ 1 GiB buffered). Every engine-touching tool takes limits (the eight named ZipLimits bounds — maxEntries, maxEntryUncompressedSize, maxTotalUncompressedSize, maxCompressionRatio, maxNameBytes, maxExtraFieldBytes, maxCommentBytes, maxCentralDirectoryBytes; values above the operator ceilings → LIMIT_CEILING_EXCEEDED) and strict (escalate the first diagnostic to ZIP_STRICT_DIAGNOSTIC). The read tools take verbosity ('full' | 'summary') and fields (≤ 16 dot paths). Every result carries diagnostics[] + diagnosticCounts (+ diagnosticsTruncated past 200). Error results: content[0].text = "<tool> failed [CODE]: message", isError: true, _meta.error = { code, message, data? }. Full input/output schemas are advertised by tools/list; the complete error table is in AGENTS.md.

inspect_zip

Read-only archive report in ONE call, the zipnative inspect --json shape: size, entry / file / directory counts, Zip64, comment (+ commentHex), compressed vs uncompressed totals and ratio, per-method counts, encrypted / symlink / data-descriptor / Zip64 / cp437 / duplicate / unsafe-name counts, earliest / latest date, prependedData / multipleEocd, a determinism verdict (epochTimestamps, canonicalOrder, utf8Flags, noDataDescriptors, canonicalLayout, deterministic — reproducible = epoch timestamps + canonical order + UTF-8 flags; a streamed archive is reproducible but not canonical; a pinned non-epoch date is reproducible but reports deterministic: false here — this is the structural verdict, distinct from create_zip.summary.deterministic) and every diagnostic. It opens the archive eagerly by default: every entry's real extent is checked up front — overlapping entries, entries reaching into the central directory or past EOF, and Zip64 spoofing are refused with their ZIP_* code rather than summarised. A method / CRC / size divergence between the central directory and a local header is not an extent problem: verify_zip (localHeaderMatch) is the one-call gate for it, and read_zip_entry / extract_zip raise ZIP_CD_LFH_MISMATCH / ZIP_SIZE_MISMATCH when the entry is read. check / assert turn it into a CI gate.

Input

Type

Default

Notes

zipBase64 / zipPath

string

exactly one

validate

'eager' | 'lazy'

'eager'

lazy defers local-header cross-checks to first read (cheaper on huge archives)

check

string[] ≤ 15

deterministic, epoch-timestamps, canonical-order, utf8-names, no-data-descriptor, canonical-layout, no-zip64, zip64, no-encryption, no-symlinks, safe-names, no-duplicates, no-diagnostics, store-only, deflate-only

assert

object

maxEntries, minEntries, maxUncompressedBytes (integers ≥ 0), maxRatio (number ≥ 1, worst per-entry ratio), has (≤ 100 exact names), method ('store' | 'deflate')

strict, limits, verbosity, fields

shared fragments

Outputs: the report above plus checks[] ({ check, ok, detail }) and checksPassed when check / assert was supplied; diagnostics[]. Summary: archiveBytes, entryCount, isZip64, compressedBytes, uncompressedBytes, encryptedCount, unsafeNameCount, duplicateNameCount, deterministic, canonicalLayout, diagnosticCount, checksPassed.

{
  "zipBase64": "<base64 ZIP>",
  "check": ["deterministic", "no-encryption", "safe-names", "no-symlinks"],
  "assert": { "maxEntries": 5000, "maxRatio": 100, "has": ["manifest.json"] },
  "verbosity": "summary",
  "fields": ["checksPassed", "checks"]
}

Errors: VALIDATION_ERROR, INPUT_TOO_LARGE, INPUT_NOT_FOUND, SECURITY_VIOLATION, INVALID_EXTENSION, LIMIT_CEILING_EXCEEDED, ZIP_STRICT_DIAGNOSTIC, and the structural ZIP_* refusals (ZIP_EOCD_NOT_FOUND, ZIP_EOCD_INCONSISTENT, ZIP_CD_INCONSISTENT, ZIP_RECORD_TRUNCATED, ZIP_SIGNATURE_MISMATCH, ZIP_ZIP64_LOCATOR_MISSING, ZIP_ZIP64_EOCD_MISPLACED, ZIP_ZIP64_CONTRADICTION, ZIP_ENTRY_OVERLAP, ZIP_CD_LFH_MISMATCH, ZIP_VALUE_UNREPRESENTABLE, ZIP_UNSUPPORTED_MULTI_DISK, ZIP_LIMIT_EXCEEDED).

list_zip_entries

Read-only central-directory inventory without decompressing anything: every entry (duplicates included) in directory order as a full row — index, name, nameEncoding, isDirectory, isSymlink, method / methodName, compressedSize, uncompressedSize, ratio, crc32, lastModified, isEncrypted, usesZip64, usesDataDescriptor, unixMode, sanitizedPath (null = the extraction gate would refuse it), comment, decoded flags, versionMadeBy / versionNeeded, hostSystem, attributes, localHeaderOffset, DOS date / time, named extraFields, rawNameHex, commentHex. Paged so a 100 000-entry archive stays token-bounded.

Input

Type

Default

Notes

zipBase64 / zipPath

string

exactly one

offset

integer ≥ 0

0

skip this many matching entries

limit

integer 1–2000

200

hasMore tells you to page

filter

object

names (≤ 1000 exact), prefix, glob (≤ 32; * in a segment, ** across, ? one char; no / = any depth; trailing / = subtree), includeDirectories (directories are listed when no filter is given)

includeExtraData

boolean

false

extra-field payloads as base64 (forensics)

validate

'lazy' | 'eager'

'lazy'

strict, limits, verbosity, fields

shared fragments

Outputs: entryCount, matchedCount, offset, limit, returnedCount, hasMore, isZip64, entries[], diagnostics[]. Summary: the counts plus names (this page).

{ "zipBase64": "<base64 ZIP>", "filter": { "prefix": "src/", "glob": ["**/*.json"] }, "limit": 50, "fields": ["entries.name", "entries.uncompressedSize", "hasMore"] }

Errors: as inspect_zip (structural refusals appear on validate: 'eager' or when the central directory itself is broken).

read_zip_entry

Read ONE entry without extracting the archive, by name (exact, case-sensitive; the last duplicate wins) or index (central-directory position — disambiguates duplicates). mode: 'data' (default) returns the decompressed content, CRC-verified, as dataBase64 or as text with encoding: 'utf8'; a range reads a byte window through the chunked stream (bounded memory, no CRC for a window). mode: 'raw' returns the compressed payload verbatim (zero-copy — feed it to inflate_raw). mode: 'verify' returns verification: { ok, crcMatch, sizeMatch, localHeaderMatch } only. Encrypted entries are refused (ZIP_UNSUPPORTED_ENCRYPTION — no decryption in this engine).

Input

Type

Default

Notes

zipBase64 / zipPath

string

exactly one

name / index

string / integer ≥ 0

exactly one

mode

'data' | 'raw' | 'verify'

'data'

encoding

'base64' | 'utf8'

'base64'

mode data only; invalid UTF-8 → ENTRY_NOT_UTF8

verifyCrc

boolean

true

mode data without range

range

{ offset ≥ 0, length 1–16777216 }

mode data only

strict, limits, verbosity, fields

shared fragments

Outputs: entry (the full row), mode, sizeBytes, crcVerified, encoding, dataBase64 / text + textLength, range: { offset, length, returned }, verification, diagnostics[]. Inline cap 16 MiB per entry (ENTRY_TOO_LARGE, data.remedy: 'range'): in mode: 'data' read a range window or use extract_zip file mode; a raw payload above the cap is not retrievable inline at all — the same remedies yield the decompressed content. An out-of-range index is ZIP_ENTRY_NOT_FOUND naming the valid range (data.remedy: 'list_zip_entries').

{ "zipBase64": "<base64 ZIP>", "name": "META-INF/MANIFEST.MF", "encoding": "utf8" }

Errors: ZIP_ENTRY_NOT_FOUND, ENTRY_TOO_LARGE, ENTRY_NOT_UTF8, ZIP_UNSUPPORTED_ENCRYPTION, ZIP_UNSUPPORTED_METHOD, ZIP_CRC_MISMATCH, ZIP_SIZE_MISMATCH, ZIP_DEFLATE_CORRUPT, ZIP_DEFLATE_TRUNCATED, ZIP_DECOMPRESSION_FAILED, ZIP_INFLATE_OUTPUT_OVERFLOW, ZIP_CD_LFH_MISMATCH, ZIP_ENTRY_OVERLAP, plus the structural refusals and wrapper codes above.

verify_zip

Deep verification in one call — zipnative's verifyZip report verbatim: eager structural validation, then every entry's CRC-32 / size / local-header agreement. ok is true when the structure is valid AND every verifiable entry passed. This tool never fails for a problem with the archive: a structural refusal lands in error: { code: 'ZIP_*', message }; an unverifiable entry is skipped ('encrypted' | 'stream-only-codec') and does not fail the archive, while an entry whose method has no codec here (anything but 0 store / 8 deflate) is reported failed (ok: false), not skipped — the engine's verdict verbatim. Only caller mistakes (bad limits, bad input) are isError. Verify before you trust: run it on any archive from an untrusted source before extract_zip.

Input

Type

Default

Notes

zipBase64 / zipPath

string

exactly one

entries

'all' | 'failed' | 'skipped' | 'none'

'all'

which per-entry rows to return

maxEntries

integer 1–100000

1000

cap on returned rows (entriesTruncated); counts always cover every entry

limits, verbosity, fields

shared fragments

Outputs: ok, error (or null), entryCount, verifiedCount, failedCount, skippedCount, entries[] ({ name, ok, crcMatch, sizeMatch, localHeaderMatch, skipped? }), entriesTruncated, diagnostics[].

{ "zipBase64": "<base64 ZIP>", "entries": "failed", "verbosity": "summary" }

Errors (caller mistakes only): VALIDATION_ERROR, INPUT_TOO_LARGE, INPUT_NOT_FOUND, SECURITY_VIOLATION, INVALID_EXTENSION, LIMIT_CEILING_EXCEEDED, ZIP_LIMIT_INVALID.

extract_zip

Extract with every engine guard ON unless you name the relaxation: zip-slip / absolute / drive / UNC / NUL / ADS / Windows-device names → ZIP_PATH_TRAVERSAL (rejectTraversal: false SKIPS them, listed in skipped; an unsafe path is never emitted); symlinks → ZIP_SYMLINK_REJECTED (rejectSymlinks: false extracts the target text as data, never a link); duplicate sanitized paths → ZIP_EXTRACT_DUPLICATE_PATH (onDuplicate); declared sizes / ratios beyond limitsZIP_LIMIT_EXCEEDED; overlapping entries and central/local divergence are always refused. The archive is opened eagerly before any plan in both modes, so the dry run runs the same open-time guards as the extraction: overlapping entries, entries reaching into the central directory or past EOF and Zip64 spoofing are refused with their ZIP_* code before a single plan row is returned (and a file-mode extraction fails before its first write, data.writtenCount: 0); a central/local divergence of method, CRC or sizes is detected when the entry is read — verify_zip (localHeaderMatch) is the one-call gate for it. In base64 mode the plan (filter, sanitize, symlink policy, duplicates, budgets) is then computed without touching any payload — includeData: false returns that plan as a dry run. In file mode every file is streamed under outputDir inside the sandbox: only the engine's sanitized path is joined, the parent's real path is checked, files are opened exclusively, and a symlink accepted through rejectSymlinks: false is written as a regular file holding the link target.

Input

Type

Default

Notes

zipBase64 / zipPath

string

exactly one

outputMode

'base64' | 'file'

'base64'

inline ≤ 16 MiB per file, ≤ 32 MiB total; file mode ≤ 4 GiB

outputDir

string

file mode: relative directory inside the sandbox (created; never overwrites)

includeData

boolean

true

base64 mode: false = dry run (paths, sizes, nothing decompressed; hostile extents refused first)

filter

object

as list_zip_entries (directories excluded unless includeDirectories)

rejectTraversal

boolean

true

false skips unsafe names into skipped

rejectSymlinks

boolean

true

false writes the target text as data

onDuplicate

'error' | 'first' | 'last'

'error'

two entries → one sanitized path

emptyDirectories

boolean

false

file mode: create explicit directory entries that hold no file

strict, limits, verbosity, fields

shared fragments

Outputs: mode, dryRun, fileCount, totalBytes, entries[] ({ path, entryName, index, sizeBytes, crc32, method, dataBase64? | filePath? }), skipped[] ({ entryName, reason: 'unsafe-path' }), outputDir, directoriesCreated, diagnostics[]; file mode adds up to 50 resource_link content blocks. Summary: mode, dryRun, fileCount, totalBytes, skippedCount, paths.

{ "zipBase64": "<base64 ZIP>", "outputMode": "file", "outputDir": "unpacked/report", "filter": { "glob": ["docs/", "*.json"] } }

Errors: ZIP_PATH_TRAVERSAL, ZIP_SYMLINK_REJECTED, ZIP_EXTRACT_DUPLICATE_PATH, ZIP_LIMIT_EXCEEDED, ZIP_ENTRY_OVERLAP, ZIP_CD_LFH_MISMATCH, ZIP_UNSUPPORTED_ENCRYPTION, ZIP_UNSUPPORTED_METHOD, ZIP_CRC_MISMATCH, ZIP_SIZE_MISMATCH, ZIP_DEFLATE_CORRUPT, ZIP_DEFLATE_TRUNCATED, ZIP_DECOMPRESSION_FAILED, ENTRY_TOO_LARGE, OUTPUT_TOO_LARGE, OUTPUT_EXISTS, IO_ERROR, MISSING_OUTPUT_PATH, SECURITY_VIOLATION, plus the structural refusals and wrapper codes.

scan_zip_forward

Walk LOCAL headers in stream order with bounded memory (zipnative's central-directory-less reader iterateZipEntries). The only tool that works on a truncated archive or a stream cut mid-way — the stream must start at a local header: it cannot skip an SFX / prepended prefix and refuses one with ZIP_SIGNATURE_MISMATCH (route prefixed archives to inspect_zip, which reports prependedData / ZIP_PREPENDED_DATA and shifts offsets; modify_zip mode: 'compact' drops the prefix) — and the only one whose result is NOT authoritative: forward iteration trusts local headers ALONE, so a hostile archive can present different content here than inspect_zip / list_zip_entries report (the upload-scanner differential). Prefer those tools whenever the whole archive is available; use this one for forensics. Names are NOT sanitized — sanitizedPath shows what the extraction gate would use. A zipPath is streamed from disk without the 1 GiB buffered cap. The wrapper never reads a PK signature: stoppedAt is derived from byte accounting (the engine leaves the rest of the stream unread when it meets a central directory).

Input

Type

Default

Notes

zipBase64 / zipPath

string

exactly one

data

'none' | 'verify' | 'include'

'none'

none skips payloads (a data-descriptor entry still costs a decompress-and-discard); verify checks CRCs; include returns content (inline caps)

filter

object

as list_zip_entries (directories included when no filter is given)

maxEntries

integer ≥ 1

10000

the default is clamped to the ZIPNATIVE_MCP_MAX_ENTRIES ceiling; an explicit value above it is LIMIT_CEILING_EXCEEDED (data.remedy: 'maxEntries ≤ N')

tolerateTruncation

boolean

false

true: a truncated / corrupt stream ends the scan with stoppedAt: 'error' + error instead of failing

strict, limits, verbosity, fields

shared fragments

Outputs: trust: 'local-headers-only', entryCount, keptCount, entries[] (rows with kept and data: { verified, bytesProduced, dataBase64? }; isSymlink / usesZip64 / unixMode are null), stoppedAt ('central-directory' — the reader met a central directory and left the rest unread | 'eof' — the whole stream was consumed without one: truncated or CD-less | 'max-entries' — more local headers remained past the budget (an archive with exactly maxEntries entries ends at 'central-directory') | 'error'), truncated, inputBytes, bytesDelivered, maxEntries (the budget in force after clamping), error, diagnostics[].

{ "zipBase64": "<base64 of a truncated download>", "tolerateTruncation": true, "verbosity": "summary" }

Errors: ZIP_STREAM_TRUNCATED, ZIP_SIGNATURE_MISMATCH, ZIP_RECORD_TRUNCATED, ZIP_DESCRIPTOR_MISMATCH, ZIP_UNSUPPORTED_CD_LESS_DESCRIPTOR, ZIP_UNSUPPORTED_ENCRYPTION, ZIP_UNSUPPORTED_METHOD, ZIP_CRC_MISMATCH, ZIP_SIZE_MISMATCH, ZIP_DEFLATE_CORRUPT, ZIP_DEFLATE_TRUNCATED, ZIP_DECOMPRESSION_FAILED, ZIP_INFLATE_OUTPUT_OVERFLOW, ZIP_LIMIT_EXCEEDED, ENTRY_TOO_LARGE, OUTPUT_TOO_LARGE, LIMIT_CEILING_EXCEEDED (all engine codes land in error under tolerateTruncation: true).

sanitize_entry_paths

Apply zipnative's single traversal gate sanitizeEntryPath() to a list of names: the safe /-separated relative form each maps to (join it under your extraction root — never the raw name), or null with the rule that fired. Use it when you extract with another tool or plan an external filesystem sink. No archive needed.

Input

Type

Default

Notes

names

string[] 1–10000

each ≤ 4096 chars, as stored in an archive

verbosity, fields

projection

Outputs: count, rejectedCount, results[] ({ name, sanitized, rejected, reason? } with reasonempty, nul, absolute, drive, unc, traversal, ads, device-name, no-segments). Summary: count, rejectedCount, rejectedNames.

{ "names": ["docs/readme.md", "../../etc/passwd", "C:\\Windows\\win.ini", "aux.txt", "a/./b//c.txt"] }

Errors: VALIDATION_ERROR.

create_zip

Write a ZIP from inline entries (dataBase64 | text | sourcePath in the sandbox, or directory: true). Reproducible on one runtime by default: canonical order (raw UTF-8 name bytes), DOS-epoch timestamps, UTF-8 names, constant attributes — defaultDate: 'now' opts out (ZIP_TIMESTAMP_NOT_PINNED diagnostic). compression.deterministic: true pins the pure-TS encoder so the bytes are identical on every runtime (summary.deflateTier: 'pure-pinned'); the default node-zlib tier is byte-stable per environment only. Three determinism verdicts, read them where they apply: summary.deterministic is true only with compression.deterministic: true on every entry and no wall-clock date (cross-runtime identity — a default call reports false although its bytes are reproducible on the same runtime); summary.sha256 (includeSha256, base64 and file mode) is the proof; inspect_zip.determinism.deterministic is the structural verdict against the canonical defaults (epoch timestamps + canonical order + UTF-8 flags — a pinned non-epoch date reproduces but reports false there). order: 'insertion' keeps call order for EPUB / JAR (mimetype first, stored). stream: true on a sourcePath feeds the file through addStream (data-descriptor layout, bounded memory, > 4 GiB refused). parallel compresses with the worker pool — byte-identical output; with no workers the engine default max(1, min(cores − 1, 8)) applies, bounded by ZIPNATIVE_MCP_WORKERS. Zip64 is emitted exactly when a field overflows — reachable here: up to 100 000 entries per call (the engine default maxEntries and the ZIPNATIVE_MCP_MAX_ENTRIES ceiling remain the effective bound), so a 65 536-entry archive auto-promotes. A name ending in / denotes a directory and cannot carry a payload (VALIDATION_ERROR — drop the slash or pass directory: true). Every archive it writes is ISO/IEC 21320-1 conformant (CI-validated).

Input

Type

Default

Notes

entries

array 0–100000

required; each: name (1–4096, /-separated; a trailing / means a directory and refuses a payload), exactly one of dataBase64 / text / sourcePath or directory: true; per entry compression, date (ISO-8601 instant, pattern ^\d{4}-\d{2}-\d{2}, 1980–2107), comment (≤ 65535), unixMode (pattern ^(?:0o)?[0-7]{3,4}$ — 3–4 octal digits such as '0644', '755', '0o755', no surrounding whitespace) xor externalAttributes (uint32), extraFields (≤ 16 { id 0–65535 except 1, dataBase64 }), stream (with sourcePath)

order

'canonical' | 'insertion'

'canonical'

defaultDate

string

DOS epoch

ISO-8601 instant or 'now' (pattern ^(?:now|\d{4}-\d{2}-\d{2}))

compression

object

deflate 6

method ('store' | 'deflate'), level 0–9, deterministic

comment

string ≤ 65535

archive comment

chunkSize

integer 1024–16777216

64 KiB

file mode streaming chunk; never changes the bytes

parallel

object

workers 0–64 (≤ ZIPNATIVE_MCP_WORKERS; omitted = the engine default max(1, min(cores − 1, 8)) bounded by the ceiling), minWorkerJobSize ≥ 1, jobTimeout 1000–600000 ms

includeSha256

boolean

false

summary.sha256 in base64 and file mode (hashed while streaming — determinism proofs)

outputMode / outputPath

'base64'

file mode: relative path ending in a container extension

strict, limits

shared fragments

Outputs: the archive as an embedded resource (≤ 50 MiB) or a resource_link; structuredContent: mode, sizeBytes, filePath, summary (typed in the tool's outputSchema: entryCount, fileCount, directoryCount, streamedCount, uncompressedBytes, order, deterministic, deflateTier, parallel: { requested, workers }, sha256), diagnostics[].

{
  "entries": [
    { "name": "mimetype", "text": "application/epub+zip", "compression": { "method": "store" } },
    { "name": "META-INF/container.xml", "text": "<container/>" },
    { "name": "OEBPS/", "directory": true }
  ],
  "order": "insertion",
  "compression": { "deterministic": true },
  "includeSha256": true,
  "outputMode": "file",
  "outputPath": "books/sample.epub"
}

Errors: VALIDATION_ERROR, INPUT_TOO_LARGE, INPUT_NOT_FOUND, OUTPUT_TOO_LARGE, OUTPUT_EXISTS, IO_ERROR, MISSING_OUTPUT_PATH, INVALID_PATH, INVALID_EXTENSION, SECURITY_VIOLATION, LIMIT_CEILING_EXCEEDED, ZIP_INVALID_ENTRY_NAME, ZIP_INVALID_OPTION, ZIP_LIMIT_EXCEEDED, ZIP_UNSUPPORTED_ZIP64_STREAMING, ZIP_INPUT_TOO_LARGE, ZIP_STRICT_DIAGNOSTIC, ZIP_API_MISUSE.

modify_zip

Edit an existing archive without recompressing anything: operations add / replace / remove / rename / setComment applied in order. mode: 'append' (default) = save(): the original bytes stay verbatim and edits are appended — fast and byte-preserving, BUT removed or replaced payloads remain in the file (data remanence: recoverable by anyone; a ZIP_DEAD_BYTES_RATIO diagnostic fires past 50 % dead bytes, and 7-Zip is known to read the stale payload). mode: 'compact' = saveCompact(): canonical rewrite, still no recompression, removed data truly gone, SFX prefix dropped. No edits and an unchanged comment return the same bytes (summary.noOp). Archives with duplicate entry names are refused.

Input

Type

Default

Notes

zipBase64 / zipPath

string

exactly one

operations

array 1–1000

{ op: 'add' | 'replace', name, dataBase64 | text | sourcePath, compression?, date?, comment?, unixMode? | externalAttributes?, extraFields?, directory? (add only) }, { op: 'remove', name }, { op: 'rename', from, to }, { op: 'setComment', comment } — the payload rules and patterns are those of create_zip (a /-terminated name with a payload is VALIDATION_ERROR)

mode

'append' | 'compact'

'append'

compression

object

engine default

for new payloads (same shape as create_zip: method, level, deterministic)

defaultDate

string

DOS epoch

for new payloads; ISO-8601 instant or 'now' (pattern ^(?:now|\d{4}-\d{2}-\d{2}); 'now'ZIP_TIMESTAMP_NOT_PINNED)

includeSha256

boolean

false

outputMode / outputPath

'base64'

strict, limits

shared fragments

Outputs: the archive as an embedded resource or a resource_link; summary (saveMode, operationsApplied, entryCountBefore, entryCountAfter, inputBytes, outputBytes, grewByBytes, noOp, sha256), diagnostics[].

{ "zipBase64": "<base64 ZIP>", "operations": [{ "op": "remove", "name": ".env" }, { "op": "rename", "from": "config.json", "to": "config/app.json" }], "mode": "compact" }

Errors: ZIP_ENTRY_NOT_FOUND, ZIP_ENTRY_EXISTS, ZIP_DUPLICATE_ENTRY_NAME, ZIP_INVALID_ENTRY_NAME, ZIP_ENTRY_OVERLAP, ZIP_CD_LFH_MISMATCH, ZIP_LIMIT_EXCEEDED, ZIP_STRICT_DIAGNOSTIC, plus the structural refusals, the output codes and the wrapper codes (data.operationIndex / data.op name the failing operation).

compute_crc32

The ZIP checksum (IEEE 802.3 CRC-32, the engine's slice-by-8 implementation) of inline bytes / text or a sandbox file (streamed in 1 MiB chunks, ≤ 1 GiB). seed continues a running CRC across consecutive chunks; expect compares against a known value. Use it to cross-check an entry's crc32 from list_zip_entries against a file on disk.

Input

Type

Default

Notes

dataBase64 / text / sourcePath

string

exactly one

seed

integer 0–4294967295

0

running CRC to continue from

expect

string

1–8 hex digits, optional 0x (pattern ^(?:0x)?[0-9a-fA-F]{1,8}$)

Outputs: crc32 (unsigned), hex (8 lowercase digits), byteLength, seed, matches (when expect was given).

{ "text": "hello world", "expect": "0d4a1185" }

Errors: VALIDATION_ERROR, INPUT_TOO_LARGE, INPUT_NOT_FOUND, SECURITY_VIOLATION.

inflate_raw

Decompress a raw DEFLATE (RFC 1951) stream — e.g. the payload from read_zip_entry mode: 'raw' — with a mandatory maxOutput bound through zipnative's resumable inflater (constant memory, exact bytesConsumed, trailing bytes reported as leftover; ZIP_INFLATE_OUTPUT_OVERFLOW past the bound). method: 'store' is a bounded pass-through; a numeric method id selects a registered codec (none beyond 0 / 8 in this server → ZIP_UNSUPPORTED_METHOD).

Input

Type

Default

Notes

dataBase64 / sourcePath

string

exactly one

maxOutput

integer ≥ 1

required; inline results further capped at 50 MiB, file results at 4 GiB

method

string

'deflate'

'deflate', 'store' or a numeric id (pattern ^(?:deflate|store|[0-9]+)$)

allowTrailing

boolean

false

accept bytes after the stream silently (always reported as leftover)

outputMode / outputPath

'base64'

file mode: .bin .dat .txt .json .xml .md .csv .html .zip .tar .raw

Outputs: the inflated bytes as an embedded resource (application/octet-stream) or a resource_link; summary (method, methodName, bytesIn, bytesOut, bytesConsumed, leftover, finished, maxOutput, trailingWarning).

{ "dataBase64": "<raw deflate payload>", "maxOutput": 1048576 }

Errors: ZIP_INFLATE_OUTPUT_OVERFLOW, ZIP_DEFLATE_CORRUPT, ZIP_DEFLATE_TRUNCATED, ZIP_UNSUPPORTED_METHOD, ZIP_UNSUPPORTED_CODEC_MODE, ZIP_API_MISUSE, OUTPUT_TOO_LARGE, and the input / output wrapper codes.

describe_engine

Offline preflight (no archive needed): server / engine / tool-API versions and the protocol string, the deflate tier in use and the pinned deterministic tier, runtime codecs (node:zlib, CompressionStream, DecompressionStream) and worker threads, the codec registry, the engine's default limits, the operator ceilings (ZIPNATIVE_MCP_MAX_UNCOMPRESSED_BYTES, ZIPNATIVE_MCP_MAX_ENTRIES, ZIPNATIVE_MCP_WORKERS), every server cap, whether the sandbox and the cache are enabled, the 39 frozen ZIP_* error codes and 11 diagnostic codes, and the engine exports this server deliberately does not expose (with why). network is always 'none'. Never cached.

Input

Type

Default

Notes

verbosity, fields

projection only

Outputs: server, engine, capabilities, codecs[], defaultLimits, ceilings, caps, sandbox, network, errorCodes[], diagnosticCodes[], unexposed[].

{ "fields": ["defaultLimits", "ceilings", "caps", "sandbox"] }

Errors: VALIDATION_ERROR.

draft_governance_issue

Draft a governance-compliant GitHub issue locally for a human to review and submit — for zipnative (engine behaviour: parsing, writing, limits, codecs) or zipnative-mcp (wrapper behaviour: schemas, sandbox, transport). The server never contacts GitHub — it has no network code path at all; it returns the draft Markdown plus a machine-readable compliance report. Present both to the user, then STOP: they review and submit under their own identity.

Input

Type

Default

Notes

title

string 8–160

required

summary

string ≥ 16

required

issueType

'bug' | 'feature' | 'security' | 'docs' | 'performance'

required

targetRepo

string 1–100

'zipnative-mcp'

documentation only

reproduction

{ command, result }

required, both non-empty

expectedBehavior

string ≥ 4

required

actualBehavior

string

the reproduction result

affectedPackages

string[] ≤ 16

['zipnative-mcp']

duplicateSearchPerformed

boolean

required, MUST be true

outputMode / outputPath

'inline' | 'file'

'inline'

file mode also writes a relative .md inside ZIPNATIVE_MCP_OUTPUT_DIR (copy it to .github/drafts/ for review — the tool never writes there)

Outputs: title, issueType, targetRepo, outputMode, filePath, sizeBytes, draftMarkdown, warnings[], compliance (zeroDependencyConfirmed, reproductionCommand, reproductionResult, duplicateSearchPerformed, affectedPackages, identityReminderShown, humanGate, environment).

{
  "title": "scan_zip_forward mis-detects the descriptor of a stored entry",
  "issueType": "bug",
  "targetRepo": "zipnative",
  "summary": "A stored entry followed by a signed data descriptor is reported as truncated by the forward reader.",
  "reproduction": { "command": "scan_zip_forward on an archive written with compression.method 'store' and stream: true", "result": "ZIP_STREAM_TRUNCATED" },
  "expectedBehavior": "The entry is read and its CRC verified.",
  "affectedPackages": ["zipnative", "zipnative-mcp"],
  "duplicateSearchPerformed": true
}

A draft that proposes a runtime dependency, omits a reproduction, or sets duplicateSearchPerformed: false is rejected with GOVERNANCE_VIOLATION. Other errors: VALIDATION_ERROR, MISSING_OUTPUT_PATH, INVALID_EXTENSION, OUTPUT_EXISTS, SECURITY_VIOLATION. See the governance_contract and draft_issue_workflow prompts for the full human-in-the-loop contract.


🔐 Security model

zipnative-mcp runs inside the host process and exposes a stdio MCP server (or a loopback-only HTTP endpoint). It treats every archive as untrusted input and performs no I/O outside the configured sandbox other than the opt-in response cache under ZIPNATIVE_MCP_CACHE_DIR.

Threat

Defence

CWE

Zip-slip path traversal (../, absolute paths, drive letters, UNC, backslashes, NUL, NTFS ADS) and Windows reserved device names (CON, NUL, AUX, COM1LPT9)

rejectTraversal: true by default → ZIP_PATH_TRAVERSAL; false skips, never emits; sanitize_entry_paths exposes the same gate for external sinks; the writer refuses such names too

CWE-22 / CWE-67

Decompression bombs (declared size, total, ratio, entry floods)

the eight ZipLimits bounds enforced while inflating, not after → ZIP_LIMIT_EXCEEDED; per-call limits can never exceed the operator ceilings; inflate_raw has a mandatory maxOutput

CWE-400 / CWE-409

Symlink entries redirecting extraction

rejectSymlinks: true by default → ZIP_SYMLINK_REJECTED; false writes the target text as a regular file — a link is never materialised

CWE-59

Overlapping entries (one payload claimed by many entries)

always-on overlap detection → ZIP_ENTRY_OVERLAP, no opt-out

CWE-405

Parser-differential smuggling (central directory vs local headers)

the central directory is authoritative; method / size / CRC divergence → ZIP_CD_LFH_MISMATCH (no opt-out), name divergence → ZIP_NAME_MISMATCH diagnostic; scan_zip_forward says trust: 'local-headers-only'

CWE-436

Zip64 sentinel spoofing

Zip64 records cross-checked against every non-sentinel classic field → ZIP_ZIP64_CONTRADICTION, no opt-out

CWE-1288

Duplicate entry names (shadowing during extraction)

onDuplicate: 'error' by default → ZIP_EXTRACT_DUPLICATE_PATH; 'first' / 'last' resolve it deliberately

CWE-694

Ambiguous EOCD / trailing garbage, 64-bit fields above 2^53

refused (ZIP_EOCD_NOT_FOUND, ZIP_VALUE_UNREPRESENTABLE), never guessed

CWE-190

  • The sandbox (ZIPNATIVE_MCP_OUTPUT_DIR) is the one filesystem boundary for reads (zipPath, sourcePath, resources/read) and writes (outputPath, outputDir, extracted files, governance drafts). Paths must be relative; absolute / UNC paths, .., NUL bytes and non-container extensions are rejected; the real path of the file read and of the parent written must stay inside (a symlink or junction planted in the sandbox is SECURITY_VIOLATION on both sides — the check is on the file itself for reads, so a file symlink cannot slip past a parent-only check); files are opened exclusively (OUTPUT_EXISTS — never overwritten); a failed write removes the partial file. Unset ⇒ base64 only (the opt-in response cache under ZIPNATIVE_MCP_CACHE_DIR is the only other file I/O).

  • Inputs are validated against strict JSON Schemas + Zod at the boundary of every tool — unknown or misspelt keys (top-level or nested) are VALIDATION_ERROR; base64 is sanity-checked (data: prefix tolerated, base64-twice rejected) before any parser runs.

  • Encryption is never performed: encrypted entries are detected, honestly skipped by verify_zip, refused by the read paths with ZIP_UNSUPPORTED_ENCRYPTION. There is no password input.

  • Every engine diagnostic goes through a sink — nothing is ever printed to stdout on the stdio transport.

  • HTTP transport (ZIPNATIVE_MCP_PORT) binds loopback only with a Host / Origin guard; it has no authentication unless ZIPNATIVE_MCP_HTTP_TOKEN is set (then 401 without a valid bearer token).

Network & egress

None, ever. The server has no network code path: no telemetry, no GitHub, no update check, no URL from any tool argument, and — unlike its PDF sibling — no operator-configurable endpoint of any kind. describe_engine reports network: 'none'. Archive bytes only ever flow back in the JSON-RPC response or into the sandbox. The engine itself never opens a socket, never touches the filesystem and never evals.

Cap

Value

stdio frame / HTTP body

256 MiB

decoded zipBase64 / inline payloads per call

128 MiB

buffered zipPath / sourcePath

1 GiB (scan_zip_forward streams a zipPath uncapped)

inline output (archive, inflated bytes, resource read)

50 MiB

file output

4 GiB (enforced while streaming)

inline entry (read_zip_entry, extract_zip, scan_zip_forward)

16 MiB

inline extraction total

32 MiB

list_zip_entries page

200 default / 2000 max

create_zip entries / modify_zip operations / sanitize_entry_paths names

100000 / 1000 / 10000

filter.names / filter.glob / extraFields per entry / fields paths

1000 / 32 / 16 / 16

scan_zip_forward maxEntries default / read_zip_entry range length / extract_zip resource links

10000 (clamped to the ceiling) / 16 MiB / 50

resources/list entries / walk depth / resources/read

1000 / 8 / 50 MiB

response cache (ZIPNATIVE_MCP_CACHE_DIR) TTL / size

3600 s / 256 MiB

diagnostics per result

200 (de-duplicated by code + entry)

engine defaults (limits)

100000 entries · 1 GiB per entry · 8 GiB total · ratio 1024 · 4096-byte names · 65535-byte extra fields and comments · 256 MiB central directory

Every row is a constant in src/caps.ts and is advertised by describe_engine.caps (stdioMaxFrameBytes, maxBase64InputBytes, maxPathInputBytes, maxBase64OutputBytes, maxFileOutputBytes, maxEntryInlineBytes, maxExtractInlineTotalBytes, maxListLimit, defaultListLimit, maxCreateEntries, maxModifyOperations, maxSanitizeNames, maxDiagnostics, maxFilterNames, maxFilterGlobs, maxExtraFields, maxFieldsPaths, defaultScanMaxEntries, maxResourceLinks, maxRangeLength, maxListedResources, maxResourceWalkDepth, maxResourceReadBytes, cacheTtlSeconds, cacheMaxBytes).

See SECURITY.md for the responsible disclosure process.


🧪 Conformance (veraZIP)

ZIP has no veraPDF — JHOVE never shipped a ZIP module and no ISO/IEC 21320-1 validator existed — so the zipnative ecosystem ships its own gate, veraZIP: an ISO/IEC 21320-1:2015 (Document Container File) validator vendored from the engine (scripts/verazip-core.mjs) that raw-parses the bytes with its own EOCD / central-directory / local-header reader and never imports zipnative — a validator that shared the engine's parser would attest the engine with the engine.

npm run validate:zip builds the server, drives the real tools/call handler (create_zip and modify_zip across every writer path — buffered, stream: true, parallel, compression.deterministic, order: 'insertion', extra fields, comments, Unix modes, append and compact) plus raw-crafted archives to write a 38-archive corpus, then validates every file clause by clause (22 check ids). The conformant set includes four hostile-but-conformant archives (zip-slip, a Windows device name, duplicate paths, a symlink entry): the ISO profile constrains the container, not the meaning of names, so they PASS the validator and extract_zip must refuse them — the gate checks both. 4 raw-crafted negative canaries must be rejected with a declared clause id. Level 0 (the ISO clauses) needs no external tool and always runs; level 1 re-tests every conformant archive with the foreign integrity tools present on the machine (unzip -t, 7z t, python -m zipfile -t, tar -tf, jar tf) and skips the absent ones visibly; VERAZIP_REQUIRED=1 (set in CI) fails closed. The corpus definition is recorded in docs/data/verazip.json and the manifest of each run in test-output/zip/manifest.json.

A PASS proves that every archive this server writes is a well-formed ISO/IEC 21320-1 document container: one self-consistent end-of-central-directory record, a central directory that agrees with every local header, only store / deflate methods, no encryption, no multi-disk fields, valid Zip64 records exactly where a field overflows. It is not a certification — validation evidence against a specific validator revision — and conformant does not mean safe: the security guards exist on top of conformance.

The gate is blocking in verazip.yml on Linux and Windows on every pull request and runs again before every publish. Every archive a test produces through a tool must also pass assertValidZip (ISO conformance included). See docs/guides/CONFORMANCE.md.


🧪 Local development

git clone https://github.com/Nizoka/zipnative-mcp.git
cd zipnative-mcp
npm install
npm run typecheck:all
npm run lint
npm test
npm run test:coverage
npm run build
npm run examples:check    # runs examples/*.json live through the tools/call handler
npm run validate:zip      # BLOCKING: build + corpus + ISO/IEC 21320-1 validation (VERAZIP_REQUIRED=1 fails closed on missing foreign tools)
node scripts/tool-shape.mjs --write   # only after a deliberate tools/list schema change (catalogue parity fixture)

Quality gate (all PRs, one line):

npm run typecheck:all && npm run lint && npm run test && npm run test:coverage && npm run build && npm run validate:zip

Smoke-test the server over stdio:

node dist/cli.js
# In another terminal, send a JSON-RPC initialize request via stdin (e.g. with the MCP Inspector).
npx @modelcontextprotocol/inspector --cli node dist/cli.js --method tools/list

Drive the built server from Claude Code with the repository's .mcp.json (run npm run build first; Claude Code asks for approval on first use and injects ${CLAUDE_PROJECT_DIR}), from Claude Desktop with absolute paths, or from the MCP Inspector — the scenario to replay and the expected results are in docs/guides/LOCAL_TESTING.md § "Drive it from Claude Code / Claude Desktop / MCP Inspector".

Run it over HTTP with a bearer token and a sandbox:

ZIPNATIVE_MCP_PORT=3000 ZIPNATIVE_MCP_HTTP_TOKEN=change-me-to-a-real-secret ZIPNATIVE_MCP_OUTPUT_DIR=/tmp/zips npx zipnative-mcp
# POST http://127.0.0.1:3000/mcp with Authorization: Bearer …

Contributors: see CONTRIBUTING.md for the full local-verification workflow — the quality gate, examples-as-tests, assertValidZip on every archive a test writes, the veraZIP corpus, and the MCP Inspector.

📣 Release process

zipnative-mcp follows the same release formalism as zipnative and pdfnative-mcp:

  • One release note file per tag in release-notes/vX.Y.Z.md (no emojis)

  • CHANGELOG.md mirrors each release bullet list

  • package.json, server.json, src/version.ts and CITATION.cff move in lock-step; TOOL_API_VERSION bumps only when a schema or error code changes

  • The veraZIP gate runs again before publish

  • GitHub Release body is copied from release-notes/vX.Y.Z.md

  • npm publication is handled by GitHub Actions Trusted Publishing (OIDC), without NPM_TOKEN, with provenance and a CycloneDX SBOM

See release-notes/TEMPLATE.md for the canonical structure and publication checklist.


📚 Project structure

src/
├── cli.ts                      # entrypoint: stdio (default, 256 MiB frames) or Streamable HTTP (ZIPNATIVE_MCP_PORT); reads the ceilings once
├── http.ts                     # Node http <-> Web Request/Response bridge, 256 MiB body cap, Host/Origin loopback guard
├── auth.ts                     # opt-in HTTP bearer token (ZIPNATIVE_MCP_HTTP_TOKEN)
├── server.ts                   # Server factory, TOOLS registry, dispatchOutput, cache hints, SERVER_INSTRUCTIONS, 7 prompts, resources
├── caps.ts                     # every byte / count cap + the operator ceilings (MAX_UNCOMPRESSED_BYTES, MAX_ENTRIES, WORKERS)
├── limits.ts                   # the eight ZipLimits bounds as an input fragment; LIMIT_CEILING_EXCEEDED
├── sandbox.ts                  # the single filesystem boundary (ZIPNATIVE_MCP_OUTPUT_DIR): container extensions, realpath check, wx writes
├── archive-input.ts            # zipBase64 XOR zipPath; buffered load or streamed ByteSource
├── base64.ts                   # base64 boundary decoding with agent-facing diagnostics
├── zip-errors.ts               # ZipError -> ToolError (the 39 frozen ZIP_* codes verbatim), zlib mapping, guard()
├── diagnostics.ts              # engine diagnostic sink (de-duplicated, capped at 200) -> diagnostics[]
├── entry.ts                    # EntryView: the CLI's --json row shape (flags, unixMode, sanitizedPath, extra fields, rawNameHex)
├── filter.ts                   # names / prefix / glob entry filter (glob matcher vendored from zipnative-cli)
├── entry-spec.ts               # create / modify payloads: compression, dates, unixMode / externalAttributes, extra fields
├── engine.ts                   # initNodeZipCodecs once; runtime capability probe
├── output.ts                   # base64 emitter / sandboxed exclusive file writer (buffered + streamed)
├── resources.ts                # zipnative://output/{+path} over every sandbox file (MIME by extension)
├── projection.ts               # verbosity / fields projection for the read tools
├── cache.ts                    # opt-in SHA-256 response cache (ZIPNATIVE_MCP_CACHE_DIR)
├── governance.ts               # AI-governance / HITL contract text + draft validation
├── errors.ts                   # ToolError, SecurityError, GovernanceError
├── version.ts                  # ZIPNATIVE_MCP_VERSION, TOOL_API_VERSION
├── index.ts                    # public library exports
└── tools/
    ├── _shared.ts              # parseInput, ProjectionShape, EngineOptionsShape, sha256Hex
    ├── inspect-zip.ts
    ├── list-zip-entries.ts
    ├── read-zip-entry.ts
    ├── verify-zip.ts
    ├── extract-zip.ts
    ├── scan-zip-forward.ts
    ├── sanitize-entry-paths.ts
    ├── create-zip.ts
    ├── modify-zip.ts
    ├── compute-crc32.ts
    ├── inflate-raw.ts
    ├── describe-engine.ts
    └── draft-governance-issue.ts
scripts/
├── verazip-core.mjs            # vendored engine-independent ISO/IEC 21320-1 validator (never imports zipnative)
├── verazip-core.d.mts          # its type declarations
├── generate-zip-corpus.mjs     # writes the veraZIP corpus through the real tools + raw-crafted canaries (npm run corpus:zip)
├── validate-zip.mjs            # the gate: level 0 (ISO clauses) + level 1 (foreign integrity tools) (npm run validate:zip)
├── helpers/zip-corpus.mjs      # the corpus definition (every writer path + the hostile-but-conformant quartet + the canaries)
├── helpers/zip-corpus.d.mts    # its type declarations
├── helpers/raw-zip-builder.mjs # engine-independent raw ZIP writer for the crafted canaries (vendored from zipnative)
├── helpers/interop-tools.mjs   # unzip / 7z / python zipfile / tar / jar probes for level 1
├── verify-issue.mjs            # governance draft checker (npm run verify:issue)
└── tool-shape.mjs              # structural tools/list fingerprint (--write refreshes tests/_fixtures/tool-shape.json)
docs/
├── AI_GUIDE.md                 # decision tree + pitfalls for agents
├── API_STABILITY.md            # the tool-API stability charter (versioning, bump rules, per-tool matrix)
├── KNOWLEDGE_BASE.md           # architecture reference + the 77-export coverage ledger (§8)
├── guides/AI_GOVERNANCE.md     # the human-in-the-loop contract, narrated
├── guides/CONFORMANCE.md       # the veraZIP gate explained
├── guides/DETERMINISM.md       # the three determinism levels and how to prove them
├── guides/INCREMENTAL.md       # modify_zip: append vs compact, remanence, the 7-Zip differential
├── guides/LOCAL_TESTING.md     # the quality gate, assertValidZip, veraZIP locally, driving the server from Claude Code / Inspector
├── guides/SECURITY.md          # threat model and defences with CWE ids
└── data/                       # errors.json (39 codes + 11 diagnostics), core-exports.json (77 exports), verazip.json (corpus counts)
examples/                       # executable tool invocations (run by tests/examples.test.ts)
tests/                          # vitest suites, one per tool / module (<tool>.test.ts, <module>.test.ts) plus:
├── _zip-fixtures.ts            # benign archives via the engine + hostile ones via _fixtures/raw-zip-builder.ts (vendored)
├── _zip-assert.ts              # assertValidZip / assertIsoConformant / expectCheck
├── _mcp-harness.ts             # in-memory legacy-handshake client
├── _http-fixture.ts            # loopback HTTP fixture (2026-07-28 envelope + legacy initialize)
├── _agent-client.ts            # the scripted MCP client of the autonomy scenario (stdio / HTTP × legacy / modern)
├── autonomy.test.ts            # S0–S17 agent scenario on stdio legacy / stdio modern / HTTP legacy / HTTP modern + bearer token
├── protocol-revisions.test.ts  # the five legacy revisions (2024-10-07 … 2025-11-25) negotiated on both transports
├── stdio-modern.test.ts        # 2026-07-28 server/discover + _meta envelope over the built CLI
├── http-modern.test.ts         # 2026-07-28 over HTTP: cache hints, Mcp-Method / Mcp-Name, -32602, batches
├── http-shutdown.test.ts       # SIGTERM in HTTP mode exits cleanly and releases the port
├── schema-lockstep.test.ts     # Zod input schemas ↔ advertised JSON Schemas (keys, required, enums, defaults, bounds, patterns)
├── catalogue-parity.test.ts    # tools/list vs tests/_fixtures/tool-shape.json (frozen baseline: tool-shape.v1.0.0.json)
├── docs-consistency.test.ts    # counts / names / codes quoted in the docs, the SFX guard, the 77-export ledger + 62 / 9 / 6 reach counts, the veraZIP corpus counts, the SECURITY cache clause, this tree
├── diagnostics-inventory.test.ts # every one of the 11 diagnostics produced by a tool call
├── zip64.test.ts               # 70 000-entry reads and a 65 536-entry create_zip (auto-promotion)
└── fixtures/interop/           # foreign-tool archives (bsdtar, PowerShell)
.mcp.json                       # drives the built server from Claude Code (stdio, sandbox under test-output/mcp-sandbox)
.github/workflows/ci.yml        # Linux (Node 22 / 24) + Windows quality gate
.github/workflows/verazip.yml   # BLOCKING veraZIP job on Linux and Windows (VERAZIP_REQUIRED=1)
.github/workflows/codeql.yml    # CodeQL static analysis
.github/workflows/scorecard.yml # OpenSSF Scorecard
.github/workflows/publish.yml   # Release-triggered Trusted Publishing (OIDC) with provenance + CycloneDX SBOM

🗺 Roadmap

v1.0.0 is the first release, on zipnative 1.0.0. The full plan — released milestones, in-progress work and long-term direction — lives in ROADMAP.md.

  • Zip64 streamingcreate_zip stream: true entries above 4 GiB are refused today (ZIP_UNSUPPORTED_ZIP64_STREAMING); the per-entry opt-in lands with the engine's post-1.0 decision record.

  • Encryption — none in 1.x by engine policy (ZipCrypto is broken); AES (AE-2) may come in a later major behind an injected crypto provider, and only then will a password input exist here.

  • HTTP page streaming — MCP 2026-07-28 still has no partial structuredContent, so large listings stay paged (offset / limit) rather than streamed.

Have a feature idea? Open an issue or PR.


⭐ Star the project

If zipnative-mcp is useful to you, please ⭐ this repository — and consider also starring the underlying engine Nizoka/zipnative. Stars help others discover the project and motivate continued development.


🤝 Contributing

Contributions are very welcome. Please read CONTRIBUTING.md, check the open issues, and follow the code of conduct.


📄 License

MIT © 2026 Nizoka

zipnative-mcp is built on top of zipnative and the Model Context Protocol TypeScript SDK.

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