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rea/docs/agent-environments.md
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166fb0820f feat(environment)!: serve the environment state by default (#5351)
* feat(environment): extract the initial state a capture's reads observed

Add the environment-state analysis view. From the parents the environment
manifest accepts, it extracts the data the capture's reads observed before
the first related write: entity types with an identity field (proved by a
path parameter or inferred from an identity name), entities with their
recorded values and provenance, documents for written non-entity paths, and
a render plan per read tool that is kept only when it reproduces the tool's
latest initial recordings from the state; every other read tool is a
recorded view with the reason. The Evidence is always inferred.

Response-body decoding moves to a domain owner shared with replay, exact
JSON parsing moves to the owner of the exact-number policy, the manifest and
state views share parent admission and record grouping, and
projectAnalysisView takes its accumulators as one object.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): bound state at redacted writes; infer identity only from items

A scenario write whose URL was redacted has no request line, so it was
dropped and reads after it counted as initial state. Such a successful
write now joins the timeline with an empty path, whose root relates to
every type, so it ends every type's state; a limitation counts them.

A list whose recordings were all empty passed the "every listed item
carries it" check vacuously and published an identity field nothing
showed; it now needs at least one item, else the view stays recorded
as no-identity.

A value that differed between two request lines of one item tool, such
as a query variant, was called volatile, and the gate then substituted
each recording's own value; only repeats of one request line now show
volatility, so differing lines go through fields-differ.

List membership is compared only while a list can still be the whole
collection, and merged entities are indexed by type and collection once,
so paged captures no longer cost pages times entities (8,000 pages of
40,000 entities: 5.7 s to 0.23 s).

Docs and the tool contract say scenario state keeps the capture's
redaction markers and how redacted writes bound it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): keep first sightings, one list pointer and linear field unions

Entities took the order of the first plan observed, and item plans run
before list plans, so a complete list read before its detail reads came
out reordered and lost "all" membership; each entity now keeps its
earliest recorded sighting.

A list plan reused the first recording's pointer for later recordings,
so a later response that was itself an entity wrapping a list was read
as that list; every recording must now locate the same list.

The field union scanned its ordered list for every key, quadratic in an
object's width; a set now answers membership.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): keep post-write values and partial lists out of the initial state

A value that changed between repeats of one request line was named
volatile whenever no write under the type's own root lay between, so a
write under another root (for example POST /api/dashboards/db before a
second GET /api/search) left its effect in the initial state. Any
recorded write between the two observations now leaves every tool of the
type recorded with reason fields-differ instead.

A list was published with membership "all" even when a total or count
envelope member exceeded the number it listed. Such a counter now makes
the membership "recorded".

Also drop a stale doc comment on ObservedEntity.order.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* docs(environment): scope item-shaped and deleted written paths out of documents

State documents are held only for list-shaped paths a POST, PUT or PATCH
tool writes. Reads of item-shaped written paths and of paths that are only
deleted stay recorded views; the guide now says so and the spec defers them
to a later increment of #4933.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): count writes in flight when a value changes between reads

The volatility check compared write start positions with the two reads,
so a write already in flight when the earlier read started was missed and
its effect was named volatile. A write now counts when its interval
overlaps the span from the earlier read's start to the later read's end.

The check also ran once per changed field and scanned every write. It now
runs once per pair of observations, answered by a binary search over the
writes in timeline order and the latest end among each prefix.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): catch cross-tool changes across writes; read only item totals

A value that changed across a write was caught only between repeats of
one tool's request line, so a list read before a write and an item read
after it put the post-write value into the initial state. Changes are
now classified per entity in timeline order after observation: across
any recorded write, a change between repeats of a line or between two
lines of the type rewrites the type (every tool recorded as
fields-differ); with no write between, a repeat's change is volatile.
The classification lives in environmentStateMerge.ts.

Any numeric member whose name contained "total" or "count" counted as
an item total, so total_pages, account_id or page_count made complete
lists partial. Item totals are now members whose name tokens include
total or count and none of page, pages or per; a string of digits counts
as a number; and a set has_more, next or next-page token member also
marks the list partial.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): keep post-write observations out of initial state

* fix(environment): retain field provenance and bound state inference work

* feat(environment): serve tool calls from the environment state

`environment-serve --state <state.json>` serves an environment from the
initial state an environment-state view extracted. Read tools whose views
are state-backed answer from a live state store: item views render the held
entity into the recorded envelope, list views render the collection or the
recorded members, and document views return the held value; a missing entity
or one lacking a required field is refused, and requests the state cannot
answer fall back to their recordings with the reason. The /agentenv data
plane implements data/reset, data/add (a rea-state/v1 document as a data
part, base64 bytes, a file:// path or an https URL, validated and replaced
atomically) and data/get, and the card advertises those operations and an
intake declaration. Stage 1 is read-only: write tools are not served in
state mode. Without --state nothing changes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* docs(environment): record verification after merging the state view's review fixes

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* feat(environment)!: serve the environment state by default

environment-serve derives the environment state at startup by running the
environment-state view in-process on the capture with the manifest's
template rules, so an environment comes with its state and a user supplies
nothing extra. The derived Evidence is the same one inspect-analysis-view
produces by hand. --state is removed; --replay-only serves exactly the
stateless replay of main. When the state cannot be derived, or its catalog
does not fit the discovery budget, the server starts in replay mode, logs
the reason and reports it in the stop summary's `state`. Exported bundles
serve the state by default too: export derives it the same way, so the
verifier's tool count and checked answer match what is served, and the
README describes the served mode.

BREAKING CHANGE: environment-serve answers read tools from the derived
state and does not serve write tools unless --replay-only is given; the
stop summary reports `state` instead of `state_evidence_id`.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): bound data-plane replies, keep batch order, cancel intake on stop

- One /agentenv response is held to 64 MiB: replies are measured as they
  are produced and one past the budget becomes a -32000 error stating it.
- Every message of a batch enters the arrival-order queue on arrival, so
  another request's reset never lands between them.
- Stopping the server, or a caller leaving, cancels the active download
  and answers queued calls `cancelled` without running them.
- file:// URIs name only this host: another host or a network share is
  refused before anything is opened.
- A loaded view value may not give an entity another identity.
- List answers refuse a member lacking a field every recording carried,
  as item answers do.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): keep bodies too deep for the state's nesting out of the state

A recorded body at the JSON depth limit was accepted by extraction, then
nested a few levels deeper as a document or entity value, so sealing the
state Evidence threw and environment-serve and environment-export stopped
instead of falling back. stateBodyJson, the one rule extraction and
serving share, now treats a body nesting deeper than the limit minus 16
levels as unusable, so its tool stays a recorded view.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): measure data-plane replies before building them

83fcc739 bounded one /agentenv response to 64 MiB, but it still
serialized each reply whole before measuring it, so a batch of data/get
calls on a large state built every refused reply in full only to drop
it. Each reply is now measured in bounded JSON parts (the shared
jsonParts encoder), its parts kept only while it fits; a reply past the
budget is counted for its exact reply_bytes but never assembled. A test
checks that a refused read is never handed to JSON.stringify whole and
that its reply_bytes is exact.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): release batch replies as they are encoded; judge exact numbers by value

answerBatch kept every settled reply in its pending array until the
batch ended, so a batch alternating data/add and data/get held each
loaded state alive; each reply now leaves the queue as it is encoded.

The exact-number policy judged a number by its recorded spelling, so a
state loaded with 1e20 came back from data/get as
100000000000000000000, which data/add refused, breaking the promise
that data/get output loads back unchanged. A number is exact only when
both its recorded spelling and the one serialization writes are safe,
so integers from 2^53 below 1e21 are refused in any spelling; replay
keeps such bodies as recorded text. A domain test checks that every
accepted number is accepted again once written back.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): keep room for refusals and framing in the reply budget

The response budget counted accepted replies only: a budget error that
replaced a reply, and a batch's brackets and commas, were not charged,
so near 64 MiB later refusals pushed the body past the advertised
limit. Every reply still to come now keeps room for its own budget
error, and a batch keeps room for its framing, so a refusal always fits
and the body never passes the budget. Reply ids and which messages are
answered come from one place shared by the replies and the reserve.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): refuse a loaded state that data/get would write past the intake limit

data/add measured only the document it was given, while data/get
writes the state back with the members a document may omit (types, the
state Evidence id, view fields and record citations). A document just
under 32 MiB could therefore load and be reported larger than any intake
accepts, breaking the data/get then data/add round trip. replace now
measures the state as data/get writes it, part by part, and refuses it
past the limit, leaving the state unchanged. The limit moves to the
state document module, so the application store can read it; the
intake re-exports it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(environment): keep merged export checks on the shared test graph

Main's export tests installed module mocks for the whole services
project, which reuses one module graph. A tarball read failure then
missed its importer, and a one-shot heap mock could be taken by another
file. Read those through bindings the tests replace for one case.

Co-authored-by: morluto <morluto@users.noreply.github.com>

* fix(environment): keep a state file whose close failed owned until it closes

A file:// data/add that could not close its descriptor dropped the handle,
and an admission failure whose cleanup close failed dropped its owner, so
nothing could retry the close or report it.

The read now runs through withOwnedRegularFile, and a failed close is
retained in a server-lifetime ArtifactResourceScope. The next file read
retries it first and answers -32000 while it is still open; inline and
https documents still load. Closing the served environment retries it again
and rejects with the unfinished close.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Kaoru0822 <208281322+kaoru0822-kitauji@users.noreply.github.com>
Co-authored-by: gensokyo-dev <gensokyo-dev@users.noreply.github.com>
Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: morluto <morluto@users.noreply.github.com>
Co-authored-by: morluto <76467478+morluto@users.noreply.github.com>
2026-10-22 05:04:57 +08:00

39 KiB

Agent environments from recorded captures

Use rea environment-serve to serve an environment manifest as an agent environment: an MCP server whose tools answer from what one retained web network capture observed, plus the environment card the agentenv framework reads to discover it. By default the server derives the state the capture observed at startup and answers read tools from it; --replay-only replays the capture's records instead. Nothing is fetched from the recorded application; every answer comes from retained Evidence. rea environment-export writes the same pair as a bundle folder agent-env run builds and runs; see Export a bundle.

rea inspect-web-network-capture /absolute/session.har har --format json > capture.json
rea inspect-analysis-view view.json --format json > manifest.json
rea environment-serve manifest.json --evidence capture.json --port 8765

The first command inspects the capture; the second projects the environment manifest view from it, where view.json wraps the capture Evidence as the inline source:

{
  "source": { "kind": "inline", "evidence": { "evidence_id": "ev_…" } },
  "view": {
    "kind": "environment-manifest",
    "template_rules": ["after-uid-literal", "opaque-token", "sibling-variance"]
  }
}

The third command serves that manifest from the state it derives from the capture; see Serve from the state. Both served files are complete REA Evidence JSON as the commands write it with --format json; the evidence member of view.json is the whole of capture.json.

From a browser scenario

The capture can also come from REA itself: a browser scenario records a scripted session in a browser REA launches, and its Evidence is a manifest parent like a HAR inspection. Select the network event family and response bodies. A replayed reply carries up to 256 KiB of a recorded body, but the scenario keeps at most max_network_body_bytes of each body (64 KiB by default), and only within its allocation budgets: base64 is charged about 11 bytes per body byte, and redaction more the shorter a declared secret is (about 35 bytes per body byte for a 12-character admin_password). A body over max_network_body_allocation_bytes (1 MiB by default) is kept as unavailable with that reason; one over max_event_allocation_bytes (4 MiB) or max_total_event_allocation_bytes (16 MiB) loses its whole content event, headers included, which the capture lists among its omissions. Either way its tool replays no body. The example raises all four so that 256 KiB bodies are kept when the declared secret has at least 12 characters:

{
  "browser": { "mode": "launch", "executable_path": "/usr/bin/chromium" },
  "start_url": { "url": "http://127.0.0.1:5230/auth", "query": [] },
  "secrets": [
    { "secret_id": "admin_password", "environment_variable": "APP_PASSWORD" }
  ],
  "actions": [
    {
      "step_id": "user",
      "action": "fill",
      "locator": { "kind": "css", "selector": "input[name=username]" },
      "value": { "source": "literal", "value": "admin" }
    },
    {
      "step_id": "password",
      "action": "fill",
      "locator": { "kind": "css", "selector": "input[type=password]" },
      "value": { "source": "secret", "secret_id": "admin_password" }
    },
    {
      "step_id": "sign-in",
      "action": "press",
      "locator": { "kind": "css", "selector": "input[type=password]" },
      "key": "Enter"
    },
    {
      "step_id": "first-memo",
      "action": "goto",
      "destination": { "url": "http://127.0.0.1:5230/m/1", "query": [] },
      "wait_until": "load"
    }
  ],
  "capture": {
    "events": ["network"],
    "network": {
      "request_body": true,
      "response_body": true,
      "header_values": false
    },
    "limits": {
      "max_network_body_bytes": 262144,
      "max_network_body_allocation_bytes": 12582912,
      "max_event_allocation_bytes": 12582912,
      "max_total_event_allocation_bytes": 67108864
    }
  }
}
APP_PASSWORD=… rea capture-browser-scenario scenario.json --format json > capture.json
rea inspect-analysis-view view.json --format json > manifest.json   # view.json wraps capture.json as before
rea environment-serve manifest.json --evidence capture.json --port 8765

Each network transaction becomes one record, in request order, and the record's ordinal is its zero-based position; a transaction whose URL carried a redacted secret is left unrepresented rather than templated, and one the capture cannot attribute to a single request and response is left unrepresented too. Tools are chosen by response media type, so a scenario that selected neither response bodies nor header values is refused; one that selected header values but no response bodies yields a manifest but no state, so it is served by replay. The browser scenario redacts credential headers and the secrets it declares; values the application returns in response bodies, such as session tokens, are kept, and the replayed body is the bytes the browser exposes for each response, with any declared secret replaced by its redaction marker (a body that redaction had to empty replays no body).

What a manifest is

An environment manifest is a projection of one application's recorded request lines into a tool surface: one tool per method and path template on the primary origin, with inferred path parameters, observed query parameter names, value-free body shapes and pointers to the parent records each tool cites. It carries no bodies and no headers. The manifest's parent_evidence_id names the capture Evidence it was projected from; the serve command refuses a manifest whose parent is not the supplied --evidence file with an invalid_request error naming both identifiers, so a manifest can never be served from records it did not cite.

The MCP catalog and environment card use a 1 KiB UTF-8 budget for each captured display sample. Observation, body-key and cited-record lists show whole values with omission counts; long method, path and query-name displays show a marked prefix. Complete values remain in manifest Evidence. Argument names longer than 64 characters use collision-safe path_<n> or query_<n> aliases; replay maps those aliases to the complete captured names.

Discovery is admitted as a complete catalog under a 1 MiB serialization reservation before the listener binds. Reservation charges up to six bytes per UTF-16 code unit for JSON escaping/UTF-8 expansion, plus schema overhead; a catalog may therefore be refused even when its compact JSON is smaller. This was calibrated with 1500 query fields and eight concurrent SDK discovery requests (183,798-byte card, 507.27 MiB sampled process-family RSS). Over-capacity catalogs return resource_constraint, retain complete input Evidence, and require a smaller capture or manifest. Fields and tools are never silently omitted. Served from the state, each description is longer and the card declares the data plane, so a catalog replay admits can exceed the reservation; the state is then unavailable and the server serves replay instead (see Serve from the state).

What replay means and does not mean

Replay answers every tool with --replay-only or when the state is unavailable, and, served from the state, each read tool whose view the state does not back. Each such MCP tool call selects one of the records its manifest tool cites and returns that record's recorded response. Selection compares the supplied path parameters against the record's path segments at the parameter indexes, then the supplied query values against the record's query string, and keeps the record with the most matches; ties keep manifest order. The result reports where the answer came from:

{
  "status": 200,
  "content_type": "application/json",
  "body": { "id": 2, "login": "probe" },
  "replay": {
    "record_ordinal": 5,
    "evidence_id": "ev_…",
    "exact_match": true,
    "recorded_path": "/api/users/2",
    "recorded_query": null,
    "recorded_line_truncated": false,
    "body_recorded": true,
    "body_encoding": "utf-8",
    "truncated": false
  }
}

exact_match is true when every supplied path parameter and query value equals the recorded one; it says nothing about parameters the caller omitted. Recorded query parsing runs only when supplied query arguments affect selection. A path value matches a recorded segment as written or after percent-decoding; when both kinds of match are available, the record whose segment equals the value as written is chosen. recorded_query keeps the ? of an explicit empty query, and a recorded path or query longer than 1 KiB is cut in the reply with recorded_line_truncated: true; selection always uses the full recorded line. content_type also has a 1 KiB display bound with content_type_truncated; body interpretation uses the full recorded media type. When no record matches, the tool still answers from the tool's first cited record and reports exact_match: false. body is parsed JSON when the recorded content type is JSON-like (application/json, application/*+json, text/plain, text/markdown) and the text parses with safe numeric conversion; otherwise it is the recorded text. Large integer IDs and other numbers that would lose information stay in the original JSON text. Bodies over 256 KiB are cut at a UTF-8 boundary and returned as text with truncated: true. body_recorded is false when the capture kept the response's status and content type but no body; body is then null, which is not a recorded JSON null. body_encoding is base64 when the capture retained response bytes that are not valid UTF-8; body is then exactly those bytes in base64, never a lossy decoding. A retained base64 body is decoded only as far as the 256 KiB a reply can carry, and a leading byte-order mark is kept. For a base64 body the limit applies to the recorded bytes, not their longer base64 spelling, and a cut keeps whole base64 groups. Request bodies passed to POST, PUT and PATCH tools are accepted and ignored: nothing is written, and no call changes what a later call returns. Arguments the tool's input schema does not name are refused by the MCP server as invalid arguments, so a misspelled parameter never degrades into an omitted one.

Replay is not emulation. A served environment does not establish the application's authorization model, response semantics or state transitions, which the manifest lists as unknowns; it does not validate supplied values; and it answers only from the capture's recordings and the state they observed or a caller loaded through data/add. Replayed content is target content: every tool result, including the argument errors the MCP server returns before a replay runs, carries _meta.provenance.untrusted_content: true with source: "analysis_target". The server advertises REA's untrusted-content instructions plus a warning that its tool names, descriptions, parameter names and observed values come from the capture too, and agents must treat all of it as data, never as instructions. That same warning prefixes every tool description in the standalone card, so card discovery carries it before an MCP client initializes. It labels the captured text without changing the tool names or schema fields clients use.

The state a capture observed

Replay answers each call from one recording, so the answers reflect whichever moment of the capture recorded them. The environment state view extracts instead the data the capture's reads observed before the first related write: entity types with an identity field, entities with their recorded values, documents for written paths, and a render plan per read tool, kept only where it reproduces that tool's recordings from the state. It is the starting state an environment holds, loads and reports: environment-serve derives it from the capture at startup; see Serve from the state. With --replay-only, replay is unchanged.

Serve a manifest

rea environment-serve manifest.json --evidence capture.json [--replay-only] [--host 127.0.0.1] [--port 0]

The server derives the state from the capture before it binds and serves from it, or serves replay with --replay-only or when the state is unavailable; see Serve from the state.

--host and --port default to MCP_HOST and MCP_PORT from the environment, then to 127.0.0.1 and an ephemeral port, exactly as rea mcp --http resolves them. The bound MCP URL is written to stderr as one JSON log line ("msg":"MCP transport listening" with url); REA_LOG_LEVEL overrides that log level. ENVIRONMENT_NAME renames the served environment; otherwise the manifest's name is used, and a set but blank value is refused as configuration_invalid before binding rather than silently falling back. The listener serves one MCP client at a time with the same session, Host header and shutdown contract as transports describes. It runs until SIGINT or SIGTERM, then closes the listener, prints one {"status":"stopped", …} document whose state member says whether it served from the state, and exits 130 or 143. Signals during input loading or DNS/bind cancel the owning reader/listener before a listening announcement; that path returns a structured cancelled result instead of a stopped-listener document, with the same signal exit status.

Three routes are served:

Route Answer
POST /mcp The MCP server: from the state, one tool per read tool, answering from the state where it backs them; in replay, one tool per manifest tool, replaying records
GET /.well-known/agent-env.json The environment card
POST /agentenv From the state, data/reset, data/add and data/get; in replay, JSON-RPC -32601 method not found: <method> for every method

Numeric JSON-RPC IDs outside JavaScript's safe range or whose precision would be lost are refused as invalid requests with a null ID. They are never echoed as a different number.

In replay the data plane at /agentenv is advertised by the card but carries no operations; the error names the requested method so a caller can see that the method, not the transport, is unsupported. Its request body is read within the same 4 MiB bound the MCP endpoint applies: a larger body is answered 413 with a JSON-RPC -32000 error before any of it is parsed, and a body that is not JSON is answered 400 with -32700. A notification (no id) gets 202 and no body, a batch gets one reply per request in it, and an empty batch, a batch of more than 100 messages, or a message that is not a JSON-RPC request (including an id that is not a string, number or null, or params that are not an object or array) gets -32600 invalid request.

The environment card

The card is the discovery document the agentenv framework reads before connecting to /mcp. A replay environment's card reads:

{
  "name": "grafana-example",
  "protocolVersion": "1.0",
  "url": "/agentenv",
  "preferredTransport": "JSONRPC",
  "additionalInterfaces": [{ "url": "/mcp", "transport": "mcp" }],
  "capabilities": {
    "extensions": null,
    "tools": [
      {
        "name": "get_users_by_id",
        "description": "GET /api/users/{numeric}; replays retained records [5, 6]; evidence ev_…",
        "inputSchema": {
          "type": "object",
          "properties": {
            "id": {
              "type": "string",
              "description": "Path segment 2 (numeric); observed: 2, 3"
            }
          },
          "required": ["id"],
          "additionalProperties": false
        }
      }
    ],
    "operations": []
  },
  "children_environments": null
}

capabilities.tools lists the same names, descriptions and input schemas that tools/list advertises over MCP. Path parameters are required strings whose description names the segment index, the templating rule and the observed values (sampled within the list budget above; the manifest keeps them all); query parameter names are optional strings; write methods accept an optional body object described by the recorded top-level key types. Each input keeps its own argument: a query name equal to a path parameter's name is advertised as query_<name>, a query name longer than 64 characters as query_<n> (its position) with the captured name sampled in its description, and the write body as request_body when a query parameter is named body. Every schema closes with additionalProperties: false, a key the echo example's schema does not carry. In replay, extensions, operations and children_environments are fixed to null, [] and null: a replay environment declares no extensions, no data-plane operations and no children. Served from the state, the card declares the three data-plane operations and one intake extension instead, leaves write tools out and describes each tool as answering from the state where the state backs it.

Serve from the state

rea environment-serve manifest.json --evidence capture.json

Before it binds, the server derives the environment state the capture observed: it runs the environment-state view on the capture in-process with the manifest's template_rules in the same order, exactly as inspect-analysis-view projects it from the same capture, so the state Evidence id it reports is the one that projection produces. The view's own budget and refusals apply, and the result is checked like the view's Evidence for this manifest: extracted from the served capture, with the manifest's rules, naming only manifest tools. The server keeps one live state, shared by every MCP session and the data plane, starting from the derived state.

A state that is unavailable does not stop the server: it logs a warning naming the error code and message before it binds, then serves replay. The state is unavailable when it cannot be derived, such as from a capture_browser_scenario capture that selected header values but no response bodies or over the view's budget, and when its catalog under the served name exceeds the discovery reservation. That check runs first, so no state is derived for it, and replay is then admitted exactly as with --replay-only. --replay-only serves replay without deriving anything; the card, tools and /agentenv answers are then exactly those of replay. The stopped document's state member reports which applied:

  • {"served": true, "evidence_id": "ev_…"}: served from the derived state.
  • {"served": false, "reason": "replay-only"}: --replay-only was given.
  • {"served": false, "reason": "unavailable", "code": "unsupported_target", "message": "…"}: the state is unavailable; code and message are those of the refusal (resource_constraint for a catalog over the reservation), as the warning logged them.

Each read tool answers according to its view in the state:

View Answer
item The entity the path arguments name, rendered into the recorded envelope of envelope_ordinal. Arguments match as replay matches them: each collection segment equals the held collection's segment as written or after percent-decoding, and the identity is the last argument percent-decoded, then as written; values are never re-split on /. Any entity the state holds answers, including one data/add loaded; query arguments only decide replay.exact_match. An entity the state does not hold, or one lacking a field every recording carried, is a tool error; a body is never invented.
list When the arguments name one of the lines the view checked exactly (its latest recordings before the first related write; every path and query value equal to the recording's, and every recorded query parameter supplied), that recorded envelope with its array rendered from the state: every entity of the collection in state order for membership: "all", or the recorded members still held. A member lacking a field every recording carried makes the call a tool error rather than a partial list.
document When the arguments name the document's checked line exactly, the state's value for it; a tool error when the state holds none.
recorded The recording, as replay answers it.

A list or document call that names no checked line, including a line recorded after a write or with other query values, answers from the recording. Every answer has the replay shape plus state: {"source": "state", "view": …} naming the entity, collection or document path, or {"source": "recording", "reason": …} with the view's reason, no-view or unrecorded-request. A state answer carries the base record's status, content type and replay provenance with truncated: false; one whose JSON would exceed 256 KiB is refused as a resource_constraint tool error rather than cut. Serving is read-only: POST, PUT, PATCH and DELETE tools, other than query POSTs, are not served, so nothing a call does changes the state. Query POSTs stay served and answer from their recordings with the reason query-body.

The data plane serves three JSON-RPC methods:

Method Result
data/reset {} after restoring the state the Evidence holds
data/add {} after replacing the whole state with one valid rea-state/v1 document
data/get {"parts": [{"kind": "data", "data": <rea-state/v1 document>}]} with state_evidence_id and the types

Calls run one at a time in arrival order across requests. Every message of a batch is queued when the batch arrives, so another request's call never lands between them and each message sees the changes of those before it; a reset sent while a download is loading applies after that load. data/add takes exactly one part: a data part whose data is the document, or a file part whose file carries bytes (base64 of UTF-8 JSON) or a uri, either a file:// URL of a local regular file, whose host is empty or localhost, or an https:// URL fetched without following redirects and within 30 seconds, including reading the body; mimeType, when given, is application/json. A file:// URL naming another host, or a UNC path such as file:////server/share/state.json, is refused before anything is opened, so a load never reaches a network share. A loaded document is at most 32 MiB, and so is the state as data/get writes it back with the members a document may omit (types, state_evidence_id, record citations), so a reported state always loads again; an inline part also stays within the 4 MiB request body bound, so larger states arrive by uri. Anything else, including {"parts": []}, is -32602 invalid params; a download that fails or answers a non-2xx status is -32000. Errors never echo the uri or the content; a file or download failure names its category in error.data.reason: not-found, permission, not-regular-file, changed or read-failed for files, timeout, http-status or network (connection, TLS or a refused redirect) for downloads, and cancelled for a download the server's stop or its caller's departure ended.

Stopping the server cancels every pending call, and a caller that leaves before its reply cancels its own: a download in progress ends, and calls not yet run are answered -32000 with error.data.reason cancelled without running. A cancelled call leaves the state unchanged, and shutdown never waits for a download.

A file:// state file whose close fails stays owned by the server, and the data/add gets -32000. The next file:// load retries that close first and, while it still fails, answers -32000 without reading another file; inline and https:// documents still load. Closing the server retries it once more and fails with the unfinished close rather than dropping the descriptor.

One /agentenv response carries at most 64 MiB of replies, twice the 32 MiB a loaded document may hold: room for a data/get of a loaded state, while a batch of reads cannot multiply a large state into one body. Replies are measured in order as they are produced, in bounded parts and before they are assembled, and room is kept for every later reply's budget error and the batch's brackets and commas, so one that would take the response past the budget is never built whole and is answered instead with -32000 whose error.data gives max_response_bytes and the reply_bytes it would have taken. That call still ran, so repeat such a read in another request. A reply no larger than that error, such as a write's {}, is always kept.

{
  "rea_state": {
    "version": 1,
    "entities": [
      {
        "type": "/api/users",
        "collection": "/api/users",
        "id": "2",
        "fields": { "id": 2, "login": "probe" }
      }
    ],
    "documents": []
  }
}

Each entity's type is a state type's collection_template, its collection matches that template segment by segment (a template parameter matches any one segment), its identity field's value is its id, and its type, collection and id are unique; view_fields is optional and names item or list views of its type. Views render their values over the entity's fields, so a view's values must not set the type's identity field to a value whose text differs from the entity's id. Spell a collection as requests spell it, as data/get reports it: list calls find entities under the checked line's recorded path. Each document names a document view once, at its initial document's path. The version, and the state_evidence_id and types that data/get reports, must match the served state, so a data/get result loads back unchanged. A number without an exact native value, or whose serialized spelling would not be read as exact (an integer from 2^53 below 1e21, such as 1e20, in any spelling), or a __proto__ member is refused rather than altered. An invalid document is -32602 naming the first problem by JSON pointer, as in /rea_state/entities/3/collection (also in error.data.path); a problem inside caller data (fields, value, types) is located at that member, so the pointer never names the caller's keys. A refused document changes nothing; a valid one replaces the whole state at once. The order of entities is the state order lists use.

Record citations stay Evidence provenance. An entity's record_ordinals may be omitted or empty and a document's record_ordinal omitted; otherwise they must be the served Evidence's citations for that entity or document, or the document is refused. After loading, an entity or document whose values equal the Evidence's cites the Evidence's records, and one whose values were edited or added cites none (record_ordinals: [], no record_ordinal), so data/get never presents a loaded value as recorded.

The card declares the operations and what data/add accepts:

{
  "extensions": [
    {
      "uri": "urn:agentenv:intake/v1",
      "description": "data/add replaces the whole environment state with one rea-state/v1 document; data/get returns the current state in the same format.",
      "params": {
        "add": [
          { "part": "data", "format": "rea-state/v1", "load": "replace" },
          {
            "part": "file",
            "format": "rea-state/v1",
            "mimeTypes": ["application/json"],
            "load": "replace"
          }
        ],
        "get": [{ "part": "data", "format": "rea-state/v1" }]
      }
    }
  ],
  "operations": ["data/reset", "data/add", "data/get"]
}

The state is a projection of recorded reads. List and document calls answer from the state only for the lines their views checked, and every recorded view answers from recordings; item calls answer for any held entity but render only the envelope one recording carried. Values copied outside entity objects, derived values and counters other than those that count a list stay as recorded; no write has an effect. An exported bundle carries no state file: its server derives the state at startup, as the export does to predict what it serves.

Export a bundle

rea environment-export writes the same pair as a bundle folder the agentenv framework runs directly, shaped like its own echo example:

rea environment-export manifest.json --evidence capture.json ./grafana-example --json
agent-env run ./grafana-example
grafana-example/
  README.md                                 provenance, what it serves, run command, rights note
  envs/grafana-example/Dockerfile           pinned image: node:24.18.0-bookworm-slim + rea-agents@<this version>
  envs/grafana-example/env.toml             environment_name = "grafana-example"
  envs/grafana-example/manifest.json        byte-exact copy of manifest.json
  envs/grafana-example/evidence.json        byte-exact copy of capture.json
  artifacts/check_grafana-example/verify.py the verifier
  tasks/smoke.json                          deploy_env (local sandbox), then env_outcome_verifier

The command reads each file once, after checking that reading and parsing the whole file, including sealing traversal, fits the process's live heap headroom (a file that does not is refused as a resource_constraint before it is read), then authenticates and cross-checks the pair as environment-serve does, so a manifest projected from another capture is refused with the same invalid_request before anything is written, and the bytes it copies are the bytes it authenticated. The bundle directory must be absent or empty; an occupied directory is refused and nothing in it changes. After checking the bundle name, the export prepares the state from the capture exactly as the bundle's server will at startup under that name, to predict what the bundle serves; an unavailable state, including one whose catalog exceeds the discovery reservation, does not stop the export, and the bundle then serves replay. The complete tool catalog the bundle serves must also fit the server's advertised catalog budget before any files are written. Privately parsed JSON is sealed once so authentication and replay share immutable response trees rather than copying the capture repeatedly. --name replaces the manifest's portable kebab-case name as the env folder and env id (Windows device names such as con and lpt1 are refused); --package-tarball <path> copies a packed rea-agents tarball into the env folder and makes the Dockerfile install it instead of the registry package and remove it in the same layer, which is how a checkout rather than a release is run. The command prints the written files with their sizes, the pinned package source, the number of tools the bundle serves as tool_count, and in state whether it serves from the state, in the shape of the serve command's stopped document.

Export uses the shared output-tree owner to check directory identities around exclusive creates, verify written bytes, and reject unowned entries before reporting success. It does not delete an inspectable partial folder on failure. Node's portable pathname APIs leave a syscall-boundary race, so the output's parent directories must be trusted. On POSIX output files use mode 0600; Windows inherits ACLs and REA does not establish owner-only access there. Choose an already private Windows destination when captured content needs it.

The Dockerfile sets MCP_HOST=0.0.0.0 and MCP_PORT=18765, the port the framework maps for an MCP server env; the framework's own deploy supplies MCP_HOST, MCP_PORT and ENVIRONMENT_NAME, so the served card carries the env's name. It installs Debian's python3 because the framework's local sandbox probes a container's readiness with python3 inside it, which the slim Node image lacks. It copies the two inputs owned by the image's non-root node user, so a private host umask cannot leave them unreadable, runs as that user and starts rea environment-serve /env/manifest.json --evidence /env/evidence.json. The env.toml names the environment because the framework otherwise reads the name from Python sources the image does not have.

verify.py is the framework's async def verify(mcp_url) shape over its Python MCP client: it lists the tools and checks the count equals the number the bundle serves (the manifest's read tools from the state, every manifest tool in replay), calls one tool with no arguments and checks the call did not fail and its status is the expected one, and returns one serve result whose description reports both checks. The tool is the first served GET tool without path parameters whose answer to no arguments is not an error, and the expected status is the status of that answer: the export calls the same answer function the server uses, from the derived state or by replay, so a state answer carries its base record's status and a replayed one its record's (an unknown recorded status stays unknown; it is not borrowed from another record). A bundle with no such tool yields a verifier that checks the count only and says so. tasks/smoke.json deploys the env on the local sandbox and runs that verifier against the env's MCP endpoint; the first run also builds the framework's own infrastructure, and the run tears everything down when it ends.

The README written into the bundle records the capture artifact's SHA-256, the capture and manifest Evidence ids, the manifest view digest, the served tool count, the derived state's Evidence id or that no state is served, and the package source. It says what the environment serves: read tools from the state the capture observed, the /agentenv data plane on it and no write tools yet, replay when the state is unavailable, and --replay-only for pure replay; it says which applies to this bundle, with the error code and message when the state is unavailable, and that neither is emulation and served content is untrusted data. It states that the recorded content belongs to the captured application and must not be published without the rights to it.

Compatibility verification

npm run verify:agentenv:environment is the hosted real-agentenv lane described in testing. It projects the Grafana-shaped source-owned capture through the built CLI, packs the checkout, exports a bundle with --package-tarball, runs it with the pinned agentenv-framework release on the runner's Docker and requires the smoke task to pass with no container left behind other than the framework's own image-registry helper, which the receipt reports. It proves that one exported bundle runs on one framework release; it does not claim any hosted platform or other framework versions.

Resource and lifecycle boundaries

The Evidence files are read once at startup through the bounded JSON input reader and authenticated as Evidence before the listener binds; a file that is not Evidence, a manifest of another view kind, a capture of another format, or a manifest projected from a different capture is refused before any port is opened. The state is derived once, in-process and before binding, from the already authenticated capture: it is projected as retained Evidence, so the capture's strings are not charged again as inline view input, and the view's 96 MiB budget bounds the derivation. Because authentication covers the capture's records, a manifest whose parent check passes cites only records the capture retains. The server keeps only the cited records' request lines and response text in memory, plus the live state when it serves from one: the derived initial state, or one validated document whose JSON was at most 32 MiB. Data-plane calls run one at a time, so at most one loaded document is being read and parsed at once; data/get serializes the held state whole. No process is launched and nothing is written to disk. No outbound network request is made unless a data/add call names an https:// uri, which is fetched once within the limits above; a file:// uri is read once. A listener that fails after binding is logged and ends the command with a resource_constraint error and exit 1 instead of serving nothing.