fix(eve): stub content-output file payloads in the compaction transcript by ruiconti · Pull Request #1255 · vercel/eve

ruiconti · 2026-07-27T20:21:07Z

Stacked on #1250 (base is rui/tool-model-output-content-parts-impl, review only the top commit). Follow-up flagged as out of scope in the #456 plan.

There is no such thing as usefully trimming base64: a truncated payload is not a smaller image, it is an invalid one. But that is exactly what the summarizer got — renderPayload JSON.stringify's tool-result outputs and clips at the 2,000-char payload limit, so a content-part image reached the checkpoint model as ~2,000 chars of truncated base64. The entire per-payload budget spent on bytes the model cannot read, crowding out the sibling text part that carried the caption.

The fix is one renderer. Compaction replaces older turns with a text checkpoint and keeps recent turns verbatim, so persisted history never needs part-level surgery — recent turns keep their images for the live vision window. Only the summarizer transcript changes: content outputs now render per part. Text parts stay raw (the checkpoint model judges what matters, same policy as other tool payloads); file parts — including the SDK's deprecated media spelling — become Attached file <name> (<mediaType>), the same stub already used for message file parts, so the model sees one summarized-attachment surface.

The same fix now covers the second boundary: capToolResults — which caps oversized tool results kept in history — stubbed file parts before its size check instead of prefix-clipping serialized base64; when stubbing alone fits, the result stays a structured content output with its text parts whole.

An e2e regression eval pins the behavior: a mock-model case where a 12KB inline file part precedes a text marker — prefix-clipping loses the marker by construction, stub rendering preserves it through the checkpoint.

The docs section gains the consequence worth designing around: a compacted image cannot be re-seen. Content parts are "look at this now"; artifacts the agent may need again belong in the sandbox, where a path can be re-read.

Other output shapes (json embedding base64 in some field) are untouched — there's no structural marker to distinguish media there, and the existing clipping already bounds them.

vercel · 2026-07-27T20:21:13Z

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github-actions · 2026-07-27T20:27:28Z

Bundle + Package Summary: `apps/fixtures/weather-agent`

Key takeaways

No notable deltas vs rui/tool-model-output-content-parts-impl (862bd05).

Delta vs `rui/tool-model-output-content-parts-impl (862bd05)`

Area	Metric	Baseline	Current	Delta
Package	Packed tarball	7.42 MB	7.42 MB	+35 B ⚠️
Package	Unpacked publish size	27.94 MB	27.94 MB	+1.9 kB ⚠️
Package	Installed footprint	68.83 MB	68.83 MB	+1.9 kB ⚠️
Package	Published files	2792	2792	0
Package	Installed files	6261	6261	0
Runtime	Unique function payloads	2	2	0
Runtime	Total function bytes	16.50 MB	16.50 MB	+2.9 kB ⚠️
Runtime	Public routes	11	11	0

Changed function payloads vs rui/tool-model-output-content-parts-impl (862bd05) (2)

Function	Status	Baseline	Current	Delta	Route changes
`functions/__server.func`	changed	8.25 MB	8.25 MB	+1.4 kB ⚠️	none
`functions/.well-known/workflow/v1/flow.func`	changed	8.25 MB	8.25 MB	+1.4 kB ⚠️	none

`eve init` install

Metric	Baseline	Current	Delta
Installed footprint	107.23 MB	107.23 MB	+1.9 kB ⚠️
Installed packages	123	123	0
dependencies	4	4	0
devDependencies	2	2	0
Dependency package bytes	42.31 MB	42.31 MB	+1.9 kB ⚠️
devDependency package bytes	5.04 MB	5.04 MB	0 B ➖

Build Metadata

Preset: vercel
Nitro: nitro@3.0.260610-beta
Output directory: apps/fixtures/weather-agent/.vercel/output
Build metadata timestamp: 2026-07-28T15:31:48.420Z
Route aliases: 11 public, 1 internal (12 total aliases)
Vercel routes in config: 14
Severity legend: 🔴 dominant/large, 🟠 notable, 🟡 watch, ⚪ small

Package Drill-Down

Package Details

Package: eve@0.27.8
Package directory: packages/eve
Tarball: 7.42 MB (eve-0.27.8.tgz)
Unpacked payload: 27.94 MB across 2792 published files
Installed footprint: 68.83 MB across 6261 installed files
Installed root package: 26.66 MB
Installed dependencies: 42.17 MB
Runtime dependencies: 2
Peer dependencies: 5 (4 optional)

Installed footprint is measured from an isolated temporary npm install of the packed tarball.

Heavy installed dependencies

eve: 26.66 MB (38.7%)
@rolldown/binding-linux-x64-gnu: 18.96 MB (27.5%)
ai: 6.51 MB (9.5%)
zod: 5.04 MB (7.3%)
nitro: 2.41 MB (3.5%)

Publish payload breakdown

Published file size
🔴 dist/src/compiled/shadcn-registry/index.js       [########################] 13.15 MB 47.1%
🟠 dist/src/compiled/experimental-ai-sdk-code-mo... [###.....................] 1.51 MB 5.4%
🟡 dist/src/compiled/@vercel/sandbox/index.js       [#.......................] 632.4 kB 2.3%
🟡 dist/src/compiled/_chunks/workflow/undici-C2Z... [#.......................] 502.4 kB 1.8%
🟡 dist/src/compiled/@chat-adapter/slack/index.js   [#.......................] 440.5 kB 1.6%
🔴 Other published files                            [#####################...] 11.71 MB 41.9%

Installed footprint breakdown

Installed package size
🔴 eve                             [########################] 26.66 MB 38.7%
🔴 @rolldown/binding-linux-x64-gnu [#################.......] 18.96 MB 27.5%
🔴 ai                              [######..................] 6.51 MB 9.5%
🔴 zod                             [#####...................] 5.04 MB 7.3%
🟠 nitro                           [##......................] 2.41 MB 3.5%
🟠 undici                          [#.......................] 1.62 MB 2.4%
🔴 Other installed packages        [#######.................] 7.63 MB 11.1%

Runtime dependencies (2)

Package	Range	Notes
`nitro`	`3.0.260610-beta`
`undici`	`7.28.0`

Peer dependencies (5)

Package	Range	Notes
`@opentelemetry/api`	`^1.0.0`	optional peer
`ai`	`catalog:`
`braintrust`	`^3.0.0`	optional peer
`just-bash`	`^3.0.0`	optional peer
`microsandbox`	`^0.5.0`	optional peer

eve init install drill-down

`eve init` install details

Command: eve init my-agent
Package manager: npm
Installed footprint: 107.23 MB across 8129 installed files
Installed packages: 123 total (117 transitive-only)
dependencies: 4 direct packages totaling 42.31 MB
devDependencies: 2 direct packages totaling 5.04 MB
Other transitive package files: 59.88 MB

Installed footprint is measured from an isolated temporary eve init my-agent using the current packed eve tarball.

Heavy installed dependencies

@typescript/typescript-linux-x64: 27.95 MB (26.1%)
eve: 26.66 MB (24.9%)
@rolldown/binding-linux-x64-gnu: 18.96 MB (17.7%)
zod: 9.00 MB (8.4%)
ai: 6.51 MB (6.1%)

Installed footprint breakdown

Installed package size
🔴 @typescript/typescript-linux-x64 [########################] 27.95 MB 26.1%
🔴 eve                              [#######################.] 26.66 MB 24.9%
🔴 @rolldown/binding-linux-x64-gnu  [################........] 18.96 MB 17.7%
🔴 zod                              [########................] 9.00 MB 8.4%
🔴 ai                               [######..................] 6.51 MB 6.1%
🟠 @types/node                      [##......................] 2.54 MB 2.4%
🔴 Other installed packages         [#############...........] 15.61 MB 14.6%

dependencies (4)

Package	Range	Installed size	Share
`@vercel/connect`	`0.4.2`	135.8 kB	0.1%
`ai`	`^7.0.38`	6.51 MB	6.1%
`eve`	`file:eve-0.27.8.tgz`	26.66 MB	24.9%
`zod`	`4.4.3`	9.00 MB	8.4%

devDependencies (2)

Package	Range	Installed size	Share
`@types/node`	`24.x`	2.54 MB	2.4%
`typescript`	`7.0.2`	2.50 MB	2.3%

Function Drill-Down

Payload Size Graph

Unique function payload size and share of total
🔴 functions/.well-known/workflow/v1/flow.func     [########################] 8.25 MB 50.0%
🔴 functions/__server.func                         [########################] 8.25 MB 50.0%

Top Function Payloads

🟠 functions/.well-known/workflow/v1/flow.func • 1 public route • 8.25 MB

Metric	Value
Public routes	`/.well-known/workflow/v1/flow`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	8.25 MB
Function files	8.25 MB across 44 files
Traced dependencies	0 B
Signal	🟠 Bundled file `_chunks/runtime-artifacts.mjs` is 1.58 MB (19.1%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 _chunks/runtime-artifacts.mjs [#############...........] 1.58 MB 19.1%
🟠 index.mjs                     [##########..............] 1.17 MB 14.2%
🟡 _libs/undici.mjs              [########................] 925.6 kB 11.2%
🟡 _chunks/world-vercel.mjs      [#######.................] 900.3 kB 10.9%
🟡 _chunks/sandbox.mjs           [######..................] 767.6 kB 9.3%
🟠 Other bundled files           [########################] 2.91 MB 35.3%

🧾 Vercel Config

{
  "handler": "index.mjs",
  "launcherType": "Nodejs",
  "shouldAddHelpers": false,
  "supportsResponseStreaming": true,
  "runtime": "nodejs24.x",
  "maxDuration": "max",
  "experimentalTriggers": [
    {
      "type": "queue/v2beta",
      "topic": "__eve776561746865722d6167656e74_wkf_workflow_*",
      "consumer": "default",
      "retryAfterSeconds": 5,
      "initialDelaySeconds": 0
    }
  ],
  "environment": {
    "WORKFLOW_PRECONDITION_GUARD": "1"
  }
}

🟠 functions/__server.func • 10 public routes, 1 internal alias • 8.25 MB

Metric	Value
Public routes	`/` `/eve/v1/callback/[token]` `/eve/v1/connections/[name]/callback/[token]` `/eve/v1/health` `/eve/v1/info` `/eve/v1/session` `/eve/v1/session/[sessionId]` `/eve/v1/session/[sessionId]/cancel` `/eve/v1/session/[sessionId]/stream` `/eve/v1/session/reset`
Internal aliases	`/__server`
Runtime	`nodejs24.x`
Handler	`index.mjs`
Payload	8.25 MB
Function files	8.25 MB across 44 files
Traced dependencies	0 B
Signal	🟠 Bundled file `_chunks/runtime-artifacts.mjs` is 1.58 MB (19.1%)

🟠 🔎 Dependency Analysis

📦 Bundled files:

Bundled file size
🟠 _chunks/runtime-artifacts.mjs [#############...........] 1.58 MB 19.1%
🟠 index.mjs                     [##########..............] 1.17 MB 14.2%
🟡 _libs/undici.mjs              [########................] 925.6 kB 11.2%
🟡 _chunks/world-vercel.mjs      [#######.................] 900.3 kB 10.9%
🟡 _chunks/sandbox.mjs           [######..................] 767.6 kB 9.3%
🟠 Other bundled files           [########################] 2.91 MB 35.3%

🧾 Vercel Config

{
  "handler": "index.mjs",
  "launcherType": "Nodejs",
  "shouldAddHelpers": false,
  "supportsResponseStreaming": true,
  "runtime": "nodejs24.x"
}

Build Timing: `e2e/fixtures/agent-tools-sandbox`

This is an informational timing measurement inside eve build, from preflight through publication. Output-size measurement and profile writing are excluded.

Build mode: deployable Vercel build with sandbox template prewarm included.

Build pipeline: 2.19 s -> 2.16 s (-37.8 ms) vs rui/tool-model-output-content-parts-impl (862bd05).
Timing is informational: shared GitHub runners are too variable for a hard timing budget.

Detailed phase timings vs `rui/tool-model-output-content-parts-impl (862bd05)`

Phase	Baseline	Current	Delta
`extension.check`	1.2 ms	6.1 ms	+4.9 ms
`project.resolve`	0.7 ms	3.4 ms	+2.7 ms
`workspace.create`	0.8 ms	1.5 ms	+0.7 ms
`host.prepare`	266.8 ms	243.5 ms	-23.3 ms
`vercel.service-prefix.resolve`	2.2 ms	2.8 ms	+0.6 ms
`nitro.create`	234.9 ms	212.2 ms	-22.7 ms
`sandbox.prewarm`	313.3 ms	306.0 ms	-7.3 ms
`nitro.cache.prepare`	0.3 ms	0.3 ms	0.0 ms
`nitro.prepare`	0.9 ms	0.9 ms	0.0 ms
`nitro.public-assets`	0.8 ms	0.8 ms	0.0 ms
`nitro.prerender`	0.6 ms	0.5 ms	-0.1 ms
`nitro.bundle`	1.36 s	1.37 s	+5.9 ms
`nitro.cache.write`	0.5 ms	0.5 ms	0.0 ms
`agent-summary.emit`	0.5 ms	0.6 ms	+0.1 ms
`nitro.close`	0.2 ms	0.1 ms	-0.1 ms
`output.publish`	4.1 ms	3.9 ms	-0.2 ms
`workspace.remove`	2.4 ms	3.2 ms	+0.8 ms

…rizer transcript renderPayload JSON.stringify's tool-result outputs and clips at the payload limit, so a content-output image reached the checkpoint model as ~2000 chars of truncated base64 — the whole budget spent on bytes it cannot read, crowding out the sibling text part carrying the caption. Content outputs now render per part: text parts stay raw for the checkpoint model to judge; file parts (and the SDK's deprecated media spelling) become the same 'Attached file <name> (<mediaType>)' stub used for message file parts, keeping one summarized-attachment surface. Persisted history is untouched — recent turns keep their images; only the summarizer transcript changes. Signed-off-by: Rui Conti <ruiconti@gmail.com>

The content-stub change duplicated the message-file stub ternary. Both cases now call renderAttachedFileStub, so the summarized-attachment surface the original commit promised cannot silently fork. Signed-off-by: Rui Conti <ruiconti@gmail.com>

…file survives A 12KB inline file part precedes the text marker deliberately: under prefix-clipping the serialized payload eats the whole transcript budget and the trailing text never reaches the checkpoint model. With stub rendering the marker survives. The mock task model reports the survival marker only when the post-compaction checkpoint still carries the tail text, so the eval fails against the old rendering by construction. Signed-off-by: Rui Conti <ruiconti@gmail.com>

The stub eval proved only that the tail marker survived — compaction dumping the entire raw payload would also pass. The case now pins every clause with a sound direction of inference through the real summarizer: - a canary buried early in the base64 payload can reach the checkpoint only if the raw payload reached the compaction prompt (and the old prefix-clipping exposes it by construction), so its absence plus the tail marker distinguishes stubbed from dumped; - the attachment filename is never spelled in any instruction, so the checkpoint can carry it only by reading the rendered stub; - a lead text part (its marker spelled nowhere else) proves the sibling before the file survives, not just the one after; - the case's own user text pins the surrounding conversation. The mock task model emits the survived marker only when all clauses hold and granular *_LOST / PAYLOAD_LEAKED diagnostics otherwise, so a failing CI run names the broken clause. Signed-off-by: Rui Conti <ruiconti@gmail.com>

The mock task model renders every request's message list as a stable role:kind sequence (kinds derive from framework sentinels, never from summarizer-written content) and embeds it in its final reply; the eval asserts the exact two-request shape: 1: system > user:task 2: system > user:checkpoint-marker > assistant:checkpoint > user:task This pins that the tool call and its 12KB result are summarized away rather than kept, and that the original task message is what the resumption replays. The shape is deterministic — the payload can never fit the fixture's keep threshold, so the stripped-tail path always runs. Verified with two local eve eval runs (5/5 gates each). Signed-off-by: Rui Conti <ruiconti@gmail.com>

…history results capToolResults prefix-clipped JSON.stringify(output) at 2000 chars, so an oversized content output kept in history became the annotation plus 2KB of raw base64 — bytes the model cannot read — while the sibling text was cut away behind them. Same failure class the summarizer transcript fix addressed, different boundary. File parts now reduce to the same text stub before the size check (stubContentOutputFileParts, shared from compaction-prompt). When stubbing alone fits, the result stays a structured content output with its text parts whole; otherwise the annotated text cap truncates readable text, never payload bytes. Signed-off-by: Rui Conti <ruiconti@gmail.com>

The eval asserted the summarizer path (checkpoint pair + transcript stub), but stubbing file parts in capToolResults made the cap heuristic satisfy the threshold in place — compaction now completes without a summarizer call, which is the fix working, not the eval's expectation. The case now pins that stronger behavior exactly: the post-cap request keeps the conversation structurally identical (task, tool call, tool result — no checkpoint pair), with the file part rewritten to its stub. Detection and every contract clause read the capped tool message directly: canary absent (payload gone), stub present, lead and tail text parts preserved in place, user text untouched. Verified with two local runs (5/5 gates). Signed-off-by: Rui Conti <ruiconti@gmail.com>

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ruiconti merged commit 71bb2c6 into main Jul 28, 2026
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fix(eve): stub content-output file payloads in the compaction transcript - #1255

fix(eve): stub content-output file payloads in the compaction transcript#1255
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Bundle + Package Summary: apps/fixtures/weather-agent

Delta vs rui/tool-model-output-content-parts-impl (862bd05)

eve init install

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Build Timing: e2e/fixtures/agent-tools-sandbox

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Bundle + Package Summary: `apps/fixtures/weather-agent`

Delta vs `rui/tool-model-output-content-parts-impl (862bd05)`

`eve init` install

`eve init` install details

Build Timing: `e2e/fixtures/agent-tools-sandbox`