rea/docs/web-network-captures.md

Historical web network captures

Use inspect_web_network_capture / inspect-web-network-capture to inspect retained producer evidence. This is an offline operation: recorded URLs are never fetched, and no browser or proxy listener is started.

rea inspect-web-network-capture /absolute/session.har har --json
rea inspect-web-network-capture /absolute/session.har har --record 2 --record 0 --json

{
  "name": "inspect_web_network_capture",
  "arguments": {
    "capture_path": "/absolute/session.har",
    "format": "har",
    "record_ordinals": [2, 0]
  }
}

Omit ordinals to return every record. Explicit selection preserves caller order and original zero-based producer ordinals; duplicate or out-of-range selections are input errors. Every record is validated before selection, so selecting one entry does not hide a malformed entry elsewhere.

Formats and upstream profiles

HAR uses unchanged [email protected] draft-06 schemas, [email protected], [email protected], [email protected] JSON visitor, and [email protected] numeric representations, pinned in the npm lockfile. Only the HAR 1.2 profile is supported. Unknown extensions remain reported evidence. Duplicate object keys, including equal values and escaped spellings, are rejected before materialization. Prototype-named members such as __proto__ are preserved as ordinary own JSON members without prototype mutation. Original capture files remain unchanged. The observed mitmproxy 12.2.3 SaveHar profile can emit postData.text: null for a missing request body. REA preserves that reported null, omitting the optional field only from its validation copy for this exact producer profile; it does not invent an empty string or body bytes.

Native mitmproxy decoding requires a caller-supplied mitmdump 12.2.3 on Linux. Set its absolute executable path:

REA_MITMDUMP_COMMAND=/absolute/mitmdump rea inspect-web-network-capture /absolute/session.mitm mitmproxy --json

REA does not install mitmproxy. Its owned process uses a private configuration directory, --no-server, and the unchanged upstream mitmproxy.io.tnetstring decoder. It does not run FlowReader migrations or convert native states to HAR. Raw IDs, state versions, flow types, backup states and unknown extensions are preserved without synthesizing connections, timestamps or content. The tested upstream source is tag v12.2.3, commit 6c09d56e4c29a92f5ad01b03199977584b8ea14f; other native tool versions return an explicit unsupported-profile diagnostic. Non-Linux native decoding is not supported by this adapter.

Reading the evidence

• artifact identifies the caller-selected file and stable snapshot digest.
• records preserve producer order/ordinals and original JSON pointers or byte ranges. No live browser transaction or scenario IDs are invented.
• reported retains the producer's fields. HAR container metadata is returned separately, with log.entries replaced by null and records_pointer identifying the record collection. This is an inspection representation, not a reconstructed HAR file.
• numeric_literals preserve HAR number lexemes and native integer/float representations, including unsafe integers and non-finite native floats. Values that cannot be safely represented as JSON numbers are null in the reported view. Unsafe standard HAR numeric fields fail schema validation; unsafe extension numbers remain available through their sidecars.
• binary_fields retain exposed bytes, base64 and SHA-256 independently of declared sizes. Valid HAR content.encoding: "base64" is decoded exactly; producer-decoded Unicode text, missing text and unknown encodings do not establish original body bytes. Post-data parameters do not reconstruct a multipart body. Native byte fields also have an exact UTF-8 display view when valid; binary sidecars establish their actual representation. Native missing content and empty content remain distinct.
• redactions identify known transport authentication exclusions and explicit sensitive-value exclusions. Redacted byte fields retain neither original bytes nor their digest. Unknown extension names and token-looking query parameters do not establish sensitivity.

Mark sensitive literal string/UTF-8 byte values with MCP sensitive_values, or repeat CLI --sensitive-value. These declarations are never persisted in Evidence parameters; the count is retained. Explicit text/UTF-8 byte matches exclude the entire field with a reported null rather than substitute a text marker or rewrite payload bytes. This prevents replacement markers from reintroducing declared literals. The file digest identifies the original artifact unless it matches an explicit declaration; in that case artifact.sha256 and Evidence subject are null with an explanation. A sensitive property name excludes that entire property and its sidecars; a scope: "property-name" redaction points to its actual parent. No substitute property name or child pointer is invented. Omitted subtrees are still validated, including canonical HAR base64. Explicitly sensitive artifact paths are empty in Evidence and omitted from locations, while the original SHA-256 and size remain available unless the digest itself is explicitly excluded. Failure messages, diagnostics and cleanup resources follow the same explicit declarations without changing error types; sensitive issue pointers identify a real ancestor instead of a fabricated coordinate. Header/cookie authentication values and known transport URL userinfo are excluded structurally, including native backups.

Generated free-text limitations follow the same literal declarations, including global, per-record and Evidence explanations added during projection. Contract field names, typed discriminators and exact decoder identities keep their canonical meanings; declarations do not rename formats or providers.

Historical evidence does not prove runtime attribution, execution or deployment authenticity. Mitmproxy messages are upstream-assembled messages, not recovered wire fragments. Native dictionary duplicate keys have the unchanged upstream decoder's last-value semantics; this adapter does not claim to recover discarded duplicates or the original numeric spelling of parsed native floats.

Resource and lifecycle boundaries

Complete evidence has a 32 MiB input, 96 MiB decoder reply and 64-level nesting budget. Exceeding a budget returns no partial success. Oversized selected captures return an input error identifying capture_path and the byte budget; owned reply/output failures remain output or provider errors. HAR runs in an owned 192 MiB Node old-generation heap with one V8 worker. Native decoding applies Linux limits of 768 MiB address space, 30 seconds CPU and 96 MiB file output; both commands have a 30-second wall deadline and independently supervised process cleanup. Owned decoder diagnostics retain at most 1 MiB across stdout and stderr; the collector drops overflow as it arrives, reports the limit failure and verifies cleanup. Heap limits alone do not establish aggregate RSS limits. When REA runs on Bun, the HAR decoder runs on Bun, which ignores these V8 heap flags; its limitations and resource failures then omit the heap sizes. On Windows, the decoder's owned Job Object instead limits its committed memory to 704 MiB, the 192 MiB budget plus a 512 MiB reserve for Bun itself. The limitations state that limit, and reaching it returns resource_constraint with process_memory_limit_bytes, whatever exit status Bun reports.

Observed decoder memory exhaustion returns resource_constraint, with the selected capture, applicable limits and retained process diagnostics. HAR's old-generation heap is fixed; inherited NODE_OPTIONS cannot raise it. Record selection happens after complete decoding and does not reduce that workload. Use a smaller capture exported by its producer or another decoder with sufficient capacity, retaining the original for provenance. Subsets do not establish complete-capture coverage. Repeating the same workload or running provider health diagnostics does not resolve the heap constraint.

Stable regular-file reads reject symlinks, replacement and concurrent changes. Private snapshots, declarations and tool configuration are removed before the result returns. Cleanup uncertainty retains the selected capture, resource and original failure information. The original capture is never changed.

Excluded coordinates and read failures

Explicitly marked values also exclude matching source coordinates and their sidecars. A hidden record coordinate is reported as location.kind: "unknown"; REA does not invent a replacement pointer. Original record ordinals and artifact digests remain available.

Host filesystem read denials return code: "access_denied", category: "unavailable", the actual EACCES/EPERM code and read-access guidance. Missing files remain input failures. Cleanup failures retain the prior structured error, including its input constraints or provider diagnostics, with explicitly marked text excluded.

An observed replacement or in-place change during stable artifact acquisition returns code: "artifact_changed", category: "integrity_mismatch" and retryable: true, retaining the selected path and reader's reason. Wait until the capture file is stable before retrying. No unstable snapshot is decoded. Command cleanup failures retain the original status and both diagnostic streams; the decoder's ownership preparation receives the same cancellation signal.

MCP advertises the same strict named input contract used by the application. Historical inspection delegates argument validation to that shared application boundary so accepted explicit-sensitive declarations also cover invalid argument names and other correction details. The SDK receives raw arguments through its Standard Schema interface; malformed inputs still fail before decoder or filesystem effects and return the normal structured REA error. Protocol-envelope validation remains owned by MCP.