bot_bottle/backend/docker/compose.py

@@ -28,6 +28,8 @@ from typing import Any
 from ...egress import (
     EGRESS_HOSTNAME,
     EGRESS_ROUTES_IN_CONTAINER,
+    egress_agent_env_entries,
+    egress_sidecar_env_entries,
 )
 from ...git_gate import GIT_GATE_HOSTNAME
 from ...log import die, warn
@@ -135,8 +137,7 @@ def _sidecar_bundle_service(plan: DockerBottlePlan) -> dict[str, Any]:
     volumes.append(_bind(ep.mitmproxy_ca_host_path, EGRESS_CA_IN_CONTAINER))
     if ep.routes:
         volumes.append(_bind(ep.routes_path.parent, str(Path(EGRESS_ROUTES_IN_CONTAINER).parent)))
-        for token_env in sorted(ep.token_env_map.keys()):
-            env.append(token_env)
+    env.extend(egress_sidecar_env_entries(ep))
 
     # --- git-gate -----------------------------------------------------
     gp = plan.git_gate_plan
@@ -220,6 +221,7 @@ def _agent_service(plan: DockerBottlePlan) -> dict[str, Any]:
     # never lands on argv or in the compose file.
     for name in sorted(plan.forwarded_env.keys()):
         env.append(name)
+    env.extend(egress_agent_env_entries(plan.egress_plan))
 
     service: dict[str, Any] = {
         "image": plan.image,

bot_bottle/backend/macos_container/launch.py

@@ -22,7 +22,12 @@ from ...bottle_state import (
     git_gate_state_dir,
     read_committed_image,
 )
-from ...egress import EGRESS_ROUTES_IN_CONTAINER, egress_resolve_token_values
+from ...egress import (
+    EGRESS_ROUTES_IN_CONTAINER,
+    egress_agent_env_entries,
+    egress_resolve_token_values,
+    egress_sidecar_env_entries,
+)
 from ...git_gate import revoke_git_gate_provisioned_keys
 from ...log import die, info, warn
 from ...supervise import QUEUE_DIR_IN_CONTAINER, SUPERVISE_PORT
@@ -350,9 +355,7 @@ def _sidecar_daemons(plan: MacosContainerBottlePlan) -> tuple[str, ...]:
 
 
 def _sidecar_env_entries(plan: MacosContainerBottlePlan) -> tuple[str, ...]:
-    env: list[str] = []
-    if plan.egress_plan.routes:
-        env.extend(sorted(plan.egress_plan.token_env_map.keys()))
+    env: list[str] = list(egress_sidecar_env_entries(plan.egress_plan))
     if plan.git_gate_plan.upstreams:
         env.append(f"BOT_BOTTLE_GIT_GATE_READY_FILE={_GIT_GATE_READY_FILE}")
     if plan.supervise_plan is not None:
@@ -420,6 +423,7 @@ def _agent_env_entries(
         env.append(f"{name}={value}")
     for name in sorted(plan.forwarded_env.keys()):
         env.append(name)
+    env.extend(egress_agent_env_entries(plan.egress_plan))
     return tuple(env)
 
 

bot_bottle/backend/smolmachines/launch.py

@@ -23,7 +23,9 @@ from typing import Callable, Generator
 
 from ...egress import (
     EGRESS_ROUTES_IN_CONTAINER,
+    egress_agent_env_entries,
     egress_resolve_token_values,
+    egress_sidecar_env_entries,
 )
 from ...supervise import QUEUE_DIR_IN_CONTAINER, SUPERVISE_PORT
 from ...util import expand_tilde
@@ -228,6 +230,9 @@ def _discover_urls(
         guest_env["GIT_GATE_URL"] = f"http://{agent_git_gate_host}"
     if agent_supervise_url:
         guest_env["MCP_SUPERVISE_URL"] = agent_supervise_url
+    for entry in egress_agent_env_entries(plan.egress_plan):
+        name, value = entry.split("=", 1)
+        guest_env[name] = value
 
     return dataclasses.replace(
         plan,
@@ -316,11 +321,7 @@ def _bundle_launch_spec(
     volumes.append((str(ep.mitmproxy_ca_host_path), EGRESS_CA_IN_CONTAINER, True))
     if ep.routes:
         volumes.append((str(ep.routes_path.parent), str(Path(EGRESS_ROUTES_IN_CONTAINER).parent), True))
-        # Bare-name entries for upstream-token slots. Their values
-        # come from the docker-run subprocess env (inherited from
-        # the operator's shell), never landing on argv.
-        for token_env in sorted(ep.token_env_map.keys()):
-            env.append(token_env)
+    env.extend(egress_sidecar_env_entries(ep))
 
     # --- git-gate ---------------------------------------------
     gp = plan.git_gate_plan

bot_bottle/dlp_detectors.py

@@ -15,6 +15,8 @@ import gzip
 import re
 import typing
 import unicodedata
+from math import log2
+from collections import Counter
 from urllib.parse import quote as url_quote
 
 try:
@@ -107,20 +109,21 @@ def redact_tokens(
     text: str,
     *,
     env: typing.Mapping[str, str] | None = None,
+    sensitive_prefixes: tuple[str, ...] = ("EGRESS_TOKEN_",),
 ) -> str:
     """Replace token pattern matches and (if env given) provisioned secrets with REDACT."""
     for _, pattern in TOKEN_PATTERNS:
         text = pattern.sub(REDACT, text)
     if env is not None:
         for key, value in env.items():
-            if key.startswith("EGRESS_TOKEN_") and value:
+            if any(key.startswith(p) for p in sensitive_prefixes) and value:
                 for variant in _encoded_variants(value):
                     text = text.replace(variant, REDACT)
     return text
 
 
 # ---------------------------------------------------------------------------
-# Known secrets detector (Phase 1b)
+# Known secrets detector
 # ---------------------------------------------------------------------------
 
 def _encoded_variants(secret: str) -> list[str]:
@@ -161,18 +164,65 @@ def _encoded_variants(secret: str) -> list[str]:
     return variants
 
 
+# ---------------------------------------------------------------------------
+# Fragmentation-resistant helpers
+# ---------------------------------------------------------------------------
+
+# Minimum length of alnum projection for projection-based checks to run.
+# Short secrets produce too many false positives in projection space.
+_ALNUM_MIN_LEN = 8
+
+# Minimum window length for the partial-substring sliding scan.
+PARTIAL_MATCH_MIN_LEN = 12
+
+
+def _alnum_projection(text: str) -> str:
+    """Return text with every non-alphanumeric character stripped.
+
+    Used for fragmentation-resistant matching: separator-injected secrets
+    (spaces, hyphens, dots inserted between characters) are identical to
+    their originals in alnum projection space.
+    """
+    return "".join(c for c in text if c.isalnum())
+
+
+def _find_partial_window(secret_alnum: str, text_alnum: str, min_len: int) -> int | None:
+    """Return the position in text_alnum where any min_len-char window of
+    secret_alnum first appears, or None.
+
+    Slides a window of width min_len across secret_alnum and searches for
+    each window in text_alnum.  The first hit position is returned.
+    """
+    if len(secret_alnum) < min_len or len(text_alnum) < min_len:
+        return None
+    for i in range(len(secret_alnum) - min_len + 1):
+        window = secret_alnum[i:i + min_len]
+        pos = text_alnum.find(window)
+        if pos >= 0:
+            return pos
+    return None
+
+
 def scan_known_secrets(
     text: str,
     *,
     location: str = "body",
     env: typing.Mapping[str, str] | None = None,
+    sensitive_prefixes: tuple[str, ...] = ("EGRESS_TOKEN_",),
     safe_tokens: typing.AbstractSet[str] | None = None,
 ) -> ScanResult | None:
     if env is None:
         return None
+
+    # Pre-compute alnum projection of the scan text once; reused per secret.
+    text_alnum: str | None = None
+
     for key, value in env.items():
-        if not key.startswith("EGRESS_TOKEN_") or not value:
+        if not any(key.startswith(p) for p in sensitive_prefixes) or not value:
             continue
+
+        # Pass 1: exact match across encoded variants (original behaviour).
+        approved_exact = False
         for variant in _encoded_variants(value):
             pos = text.find(variant)
             if pos >= 0:
@@ -180,6 +230,7 @@ def scan_known_secrets(
                 # (PRD 0062); a different encoding of the same secret is a
                 # fresh block.
                 if safe_tokens is not None and variant in safe_tokens:
+                    approved_exact = True
                     continue
                 return ScanResult(
                     severity="block",
@@ -188,6 +239,104 @@ def scan_known_secrets(
                     context=_snippet(text, pos, pos + len(variant)),
                     matched=variant,
                 )
+        if approved_exact:
+            # Exact match was found and approved; projection passes would
+            # fire on the same value, so skip them for this secret.
+            continue
+
+        # Pass 2 & 3: fragmentation-resistant projection checks.
+        secret_alnum = _alnum_projection(value)
+        if len(secret_alnum) < _ALNUM_MIN_LEN:
+            continue
+
+        if text_alnum is None:
+            text_alnum = _alnum_projection(text)
+
+        # Pass 2: full alnum-projection exact match (catches separator injection).
+        pos2 = text_alnum.find(secret_alnum)
+        if pos2 >= 0:
+            return ScanResult(
+                severity="block",
+                reason=(
+                    f"provisioned secret from {key} found in {location} "
+                    f"(fragmented match — separator injection)"
+                ),
+                location=location,
+                context=_snippet(text_alnum, pos2, pos2 + len(secret_alnum)),
+            )
+
+        # Pass 3: sliding-window partial match (catches chunked-substring leaks).
+        pos3 = _find_partial_window(secret_alnum, text_alnum, PARTIAL_MATCH_MIN_LEN)
+        if pos3 is not None:
+            return ScanResult(
+                severity="block",
+                reason=(
+                    f"provisioned secret from {key} found in {location} "
+                    f"(partial match — at least {PARTIAL_MATCH_MIN_LEN} consecutive "
+                    f"alphanumeric chars)"
+                ),
+                location=location,
+                context=_snippet(text_alnum, pos3, pos3 + PARTIAL_MATCH_MIN_LEN),
+            )
+
+    return None
+
+
+# ---------------------------------------------------------------------------
+# Entropy detector (warn-only)
+# ---------------------------------------------------------------------------
+
+# Sliding window size and step for the entropy scan.
+ENTROPY_WINDOW = 64
+ENTROPY_STEP = 32
+
+# Bits-per-character threshold.  Random ASCII printable ≈ 6.6 bits; random
+# lowercase hex ≈ 4 bits; random base64url ≈ 6 bits.  5.5 sits above
+# typical structured data (JSON, URLs) while staying below truly random
+# content.
+ENTROPY_BLOCK_THRESHOLD = 5.5
+
+
+def _shannon_entropy(text: str) -> float:
+    if not text:
+        return 0.0
+    counts = Counter(text)
+    n = len(text)
+    return -sum((c / n) * log2(c / n) for c in counts.values())
+
+
+def scan_entropy(
+    text: str,
+    *,
+    location: str = "body",
+    window: int = ENTROPY_WINDOW,
+    threshold: float = ENTROPY_BLOCK_THRESHOLD,
+) -> ScanResult | None:
+    """Warn-only detector: flag windows of `window` chars with Shannon entropy
+    above `threshold` bits per character.
+
+    Never blocks; always returns severity='warn'.  Disabled by default —
+    routes must opt in via dlp.outbound_detectors=['entropy'].
+    """
+    if not text:
+        return None
+    step = max(1, window // 2)
+    end = len(text)
+    # Scan overlapping windows; also check the final tail if shorter than window.
+    positions = list(range(0, end - window + 1, step))
+    if end < window:
+        positions = [0]
+    elif (end - window) % step != 0:
+        positions.append(end - window)
+    for i in positions:
+        chunk = text[i:i + window]
+        if _shannon_entropy(chunk) >= threshold:
+            return ScanResult(
+                severity="warn",
+                reason=f"high-entropy content in {location} (possible encrypted exfil)",
+                location=location,
+                context=_snippet(text, i, i + len(chunk)),
+            )
     return None
 
 
@@ -306,11 +455,18 @@ def scan_crlf_injection(text: str) -> ScanResult | None:
 
 
 __all__ = [
+    "ENTROPY_BLOCK_THRESHOLD",
+    "ENTROPY_WINDOW",
+    "ENTROPY_STEP",
+    "PARTIAL_MATCH_MIN_LEN",
     "REDACT",
     "SNIPPET_CONTEXT",
     "TOKEN_PATTERNS",
+    "_alnum_projection",
+    "_shannon_entropy",
     "redact_tokens",
     "scan_crlf_injection",
+    "scan_entropy",
     "scan_known_secrets",
     "scan_naive_injection",
     "scan_token_patterns",

bot_bottle/egress.py

@@ -10,6 +10,7 @@ specific and lives on concrete subclasses (see
 from __future__ import annotations
 
 import dataclasses
+import secrets
 from abc import ABC
 from dataclasses import dataclass
 from pathlib import Path
@@ -34,6 +35,50 @@ EGRESS_HOSTNAME = "egress"
 EGRESS_ROUTES_IN_CONTAINER = "/etc/egress/routes.yaml"
 EGRESS_ROUTES_FILENAME = Path(EGRESS_ROUTES_IN_CONTAINER).name
 
+_CANARY_ENV_WORDS = (
+    "ACCORD",
+    "ANCHOR",
+    "ATLAS",
+    "CANON",
+    "CIPHER",
+    "EMBER",
+    "FALCON",
+    "HARBOR",
+    "LANTERN",
+    "MARBLE",
+    "NOVA",
+    "ORBIT",
+    "PIVOT",
+    "RADIUS",
+    "SUMMIT",
+    "VECTOR",
+)
+
+
+def _random_canary_env() -> str:
+    first = secrets.choice(_CANARY_ENV_WORDS)
+    remaining = tuple(word for word in _CANARY_ENV_WORDS if word != first)
+    second = secrets.choice(remaining)
+    return f"{first}_{second}_SECRET"
+
+
+def egress_sidecar_env_entries(plan: "EgressPlan") -> tuple[str, ...]:
+    """Return sidecar env entries needed by egress across all backends."""
+    env: list[str] = []
+    if plan.routes:
+        env.extend(sorted(plan.token_env_map.keys()))
+    if plan.canary and plan.canary_env:
+        env.append(f"{plan.canary_env}={plan.canary}")
+        env.append(f"BOT_BOTTLE_SENSITIVE_PREFIXES={plan.canary_env}")
+    return tuple(env)
+
+
+def egress_agent_env_entries(plan: "EgressPlan") -> tuple[str, ...]:
+    """Return agent-visible egress env entries shared by all backends."""
+    if plan.canary and plan.canary_env:
+        return (f"{plan.canary_env}={plan.canary}",)
+    return ()
+
 
 @dataclass(frozen=True)
 class EgressRoute(Route):
@@ -65,6 +110,8 @@ class EgressPlan:
     mitmproxy_ca_host_path: Path = Path()
     mitmproxy_ca_cert_only_host_path: Path = Path()
     log: int = 0
+    canary: str = ""
+    canary_env: str = ""
 
 
 def egress_manifest_routes(
@@ -324,12 +371,18 @@ class Egress(ABC):
         routes_path = stage_dir / EGRESS_ROUTES_FILENAME
         routes_path.write_text(egress_render_routes(routes, log=log))
         routes_path.chmod(0o600)
+        # Generate a per-session fake secret under a plausible random env name.
+        # The sidecar marks that exact env name as sensitive for known-secret
+        # scanning; the agent receives the same name/value as exfil bait.
+        canary = secrets.token_urlsafe(32)
         return EgressPlan(
             slug=slug,
             routes_path=routes_path,
             routes=routes,
             token_env_map=egress_token_env_map(routes),
             log=log,
+            canary=canary,
+            canary_env=_random_canary_env(),
         )
 
 __all__ = [
@@ -344,5 +397,7 @@ __all__ = [
     "egress_render_routes",
     "egress_resolve_token_values",
     "egress_routes_for_bottle",
+    "egress_agent_env_entries",
+    "egress_sidecar_env_entries",
     "egress_token_env_map",
 ]

bot_bottle/egress_addon_core.py

@@ -34,7 +34,7 @@ VALID_METHODS = frozenset({
     "CONNECT",
 })
 
-OUTBOUND_DETECTOR_NAMES = frozenset({"token_patterns", "known_secrets"})
+OUTBOUND_DETECTOR_NAMES = frozenset({"token_patterns", "known_secrets", "entropy"})
 INBOUND_DETECTOR_NAMES = frozenset({"naive_injection_detection"})
 
 # Per-route policy for what the proxy does when an outbound DLP detector
@@ -729,17 +729,28 @@ def scan_outbound(
     try:
         from dlp_detectors import (  # type: ignore[import-not-found]
             scan_crlf_injection,
+            scan_entropy,
             scan_known_secrets,
             scan_token_patterns,
         )
     except ImportError:  # pragma: no cover - host-side path
         from .dlp_detectors import (  # type: ignore[import-not-found]
             scan_crlf_injection,
+            scan_entropy,
             scan_known_secrets,
             scan_token_patterns,
         )
 
-    text = body if isinstance(body, str) else body.decode("utf-8", errors="replace")
+    # Binary bodies: latin-1 is a bijective byte↔codepoint mapping that
+    # preserves every byte value, so ASCII-range secret strings remain
+    # findable by str.find / regex.  Prefer strict UTF-8 for valid text bodies.
+    if isinstance(body, bytes):
+        try:
+            text = body.decode("utf-8")
+        except UnicodeDecodeError:
+            text = body.decode("latin-1")
+    else:
+        text = body
 
     # CRLF injection is only an attack in the request line + headers, never the
     # body: an HTTP body is delimited by Content-Length, so CRLF bytes there
@@ -758,12 +769,30 @@ def scan_outbound(
             return result
 
     if _detector_enabled(route.outbound_detectors, "known_secrets"):
+        # BOT_BOTTLE_SENSITIVE_PREFIXES lets operators add extra env prefixes
+        # beyond EGRESS_TOKEN_* without changing the manifest schema.
+        extra_raw = environ.get("BOT_BOTTLE_SENSITIVE_PREFIXES", "")
+        extra = tuple(p for p in extra_raw.split(",") if p)
+        sensitive_prefixes = ("EGRESS_TOKEN_",) + extra
         result = scan_known_secrets(
-            text, location="body", env=environ, safe_tokens=safe_tokens,
+            text, location="body", env=environ,
+            sensitive_prefixes=sensitive_prefixes, safe_tokens=safe_tokens,
         )
         if result is not None:
             return result
 
+    # Entropy scanning requires explicit opt-in: it is NOT part of the
+    # default "all detectors" set because it produces false positives on
+    # legitimate base64 / binary payloads.  Routes must list "entropy" in
+    # dlp.outbound_detectors to enable it.
+    if (
+        route.outbound_detectors is not None
+        and "entropy" in route.outbound_detectors
+    ):
+        result = scan_entropy(text, location="body")
+        if result is not None:
+            return result
+
     return None
 
 

docs/prds/prd-new-strengthen-outbound-exfil-detection.md

@@ -0,0 +1,189 @@
+# PRD prd-new: Strengthen outbound exfiltration detection
+
+- **Status:** Active
+- **Author:** claude
+- **Created:** 2026-06-25
+- **Issue:** #259
+
+## Summary
+
+The current DLP system has two detection tiers: weak (vendor token regexes)
+and strong (exact matching of provisioned `EGRESS_TOKEN_*` values in multiple
+encodings). This PRD adds four complementary hardening layers in ranked order
+of impact:
+
+1. **Canary tokens** — inject a per-session fake secret into the agent's
+   environment; any outbound appearance is a zero-false-positive exfil signal.
+2. **Broadened known-value scanning** — extend the strong tier beyond
+   `EGRESS_TOKEN_*` via a `BOT_BOTTLE_SENSITIVE_PREFIXES` sidecar env var.
+3. **Fragmentation-resistant matching** — catch separator injection and
+   long-substring leaks via alnum projection and sliding-window substring
+   search.
+4. **Entropy scoring** — warn-only flag on high-entropy blobs as a
+   complementary signal for encrypted exfil.
+
+## Problem
+
+After PRD 0056 the outbound scan covers all HTTP request surfaces (host, path,
+query, headers, body). But the content-based strong tier only matches
+`EGRESS_TOKEN_*` values and their encodings. Three gaps remain:
+
+| Gap | How an agent exploits it |
+|-----|--------------------------|
+| No canary | There is no "can't be false-positive" signal |
+| Narrow prefix filter | Sensitive values provisioned under other env prefixes (MCP keys, API keys injected via the agent provider) are invisible to `scan_known_secrets` |
+| Fragmentation blindness | Inserting `-`, space, or `\n` between secret characters turns an exact-match into a miss |
+
+## Goals / Success Criteria
+
+1. Each launched bottle has a unique canary token in the agent's environment
+   under a randomized `WORD_WORD_SECRET` env var name. The egress sidecar gets
+   the same env var and registers that exact name through
+   `BOT_BOTTLE_SENSITIVE_PREFIXES`. Any outbound appearance of the canary
+   blocks the request as a known-secret match.
+2. `scan_known_secrets` accepts a `sensitive_prefixes` parameter (default:
+   `("EGRESS_TOKEN_",)`). `scan_outbound` reads
+   `BOT_BOTTLE_SENSITIVE_PREFIXES` from `environ` and merges those prefixes
+   in, so operators can mark additional env vars as scanned values without
+   changing the manifest schema.
+3. For every secret that passes exact-match, a secondary alnum-projection pass
+   checks for the secret with all non-alphanumeric characters stripped. This
+   catches separator-injection evasion (`MY-SECRET` → body contains
+   `MY SECRET`).
+4. A sliding-window partial-match pass checks for long-enough contiguous
+   substrings of the secret's alnum projection in the text's alnum projection.
+   Any match ≥ `PARTIAL_MATCH_MIN_LEN` (12 chars) blocks with reason
+   `"partial match"`.
+5. A new `scan_entropy` detector flags outbound text windows with Shannon
+   entropy ≥ `ENTROPY_BLOCK_THRESHOLD` (5.5 bits/char) at **warn** severity
+   only. It is registered under the new detector name `"entropy"` in
+   `OUTBOUND_DETECTOR_NAMES` and disabled by default (routes must opt in).
+6. Binary request bodies are decoded via `latin-1` instead of
+   `utf-8 errors="replace"`, preserving every byte value and allowing
+   ASCII-range secrets to be found within binary payloads.
+7. All new behaviour is unit-tested; existing tests pass unchanged.
+
+## Non-goals
+
+- Rolling per-host buffer for split-across-requests detection (state in the
+  stateless addon is complex; deferred).
+- Additional vendor regexes.
+- ML / embedding-based detection.
+- Entropy-based hard blocks (warn only per the issue).
+
+## Design
+
+### Canary token flow
+
+```
+Egress.prepare()
+  canary = secrets.token_urlsafe(32)
+  canary_env = <random WORD_WORD_SECRET>
+  EgressPlan(canary=canary, canary_env=canary_env, ...)
+
+Docker compose render:
+  sidecar env: <canary_env>=<canary>
+  sidecar env: BOT_BOTTLE_SENSITIVE_PREFIXES=<canary_env>
+  agent env:   <canary_env>=<canary>      ← visible to agent as a "secret"
+
+macos-container launch: same literals added to sidecar + agent env entries
+```
+
+The sidecar uses `BOT_BOTTLE_SENSITIVE_PREFIXES` to make the random canary env
+name part of the existing `scan_known_secrets` detector without adding a
+manifest schema field.
+
+### Broadened known-value scanning
+
+`scan_known_secrets` gains a `sensitive_prefixes` parameter:
+
+```python
+def scan_known_secrets(
+    text: str,
+    *,
+    location: str = "body",
+    env: Mapping[str, str] | None = None,
+    sensitive_prefixes: tuple[str, ...] = ("EGRESS_TOKEN_",),
+) -> ScanResult | None:
+```
+
+`scan_outbound` reads `BOT_BOTTLE_SENSITIVE_PREFIXES` (comma-separated list
+of additional prefixes) from `environ` and appends them:
+
+```python
+extra = tuple(
+    p for p in environ.get("BOT_BOTTLE_SENSITIVE_PREFIXES", "").split(",") if p
+)
+sensitive_prefixes = ("EGRESS_TOKEN_",) + extra
+```
+
+`redact_tokens` receives the same treatment for consistent redaction.
+
+### Fragmentation-resistant matching
+
+A new helper `_alnum_projection(text)` strips all non-alphanumeric characters.
+`scan_known_secrets` runs two passes per secret:
+
+1. **Exact pass** — existing encoded-variant loop (unchanged).
+2. **Alnum-projection pass** — if the secret's alnum projection has ≥ 8 chars,
+   check if it appears in the text's alnum projection. Match → block with
+   `"fragmented match (separator injection)"` reason.
+3. **Partial-substring pass** — if the secret's alnum projection has ≥
+   `PARTIAL_MATCH_MIN_LEN` chars (12), slide a window of that length across the
+   secret's projection and look for each window in the text's alnum projection.
+   First match → block with `"partial match"` reason.
+
+All three passes run only for the `"known_secrets"` detector; the token-pattern
+and entropy detectors are unchanged.
+
+### Entropy scoring
+
+New public function:
+
+```python
+def scan_entropy(
+    text: str,
+    *,
+    location: str = "body",
+    window: int = ENTROPY_WINDOW,           # 64
+    threshold: float = ENTROPY_BLOCK_THRESHOLD,  # 5.5
+) -> ScanResult | None:
+```
+
+Slides a window of `window` characters across `text` in steps of `window // 2`.
+If any window's Shannon entropy exceeds `threshold`, returns a **warn**-severity
+`ScanResult`. Never blocks.
+
+`OUTBOUND_DETECTOR_NAMES` gains `"entropy"`. Routes opt in via their `dlp`
+block; entropy scanning is **off by default** to avoid false-positive noise on
+legitimate binary payloads.
+
+### Binary body handling
+
+In `scan_outbound`, the bytes → str decoding changes from:
+
+```python
+body.decode("utf-8", errors="replace")
+```
+
+to:
+
+```python
+body.decode("utf-8") if body is str else body.decode("latin-1")
+```
+
+`latin-1` is a bijective byte↔codepoint mapping; every byte value is preserved
+as its corresponding Latin-1 code point, so ASCII-range secret strings remain
+intact and `str.find` / regex still locate them correctly. The fallback from
+strict UTF-8 is tried first so valid UTF-8 bodies are decoded faithfully.
+
+## Implementation
+
+Delivered in three commits on the same branch:
+
+1. **DLP detector changes** — `_alnum_projection`, fragmentation passes,
+   `scan_entropy`, broadened `scan_known_secrets`, updated `scan_outbound` and
+   `redact_tokens`; all accompanying unit tests.
+2. **Canary injection** — `EgressPlan.canary`, `Egress.prepare()`,
+   Docker compose + macos-container backend injection.
+3. **PRD flip** — `Status: Draft → Active`.

tests/unit/test_compose.py

@@ -80,7 +80,11 @@ def _git_gate_plan(upstreams: tuple[GitGateUpstream, ...] = ()) -> GitGatePlan:
     )
 
 
-def _egress_plan(routes: tuple[EgressRoute, ...] = ()) -> EgressPlan:
+def _egress_plan(
+    routes: tuple[EgressRoute, ...] = (),
+    *,
+    canary: bool = False,
+) -> EgressPlan:
     token_env_map = {
         r.token_env: r.token_ref
         for r in routes
@@ -95,6 +99,8 @@ def _egress_plan(routes: tuple[EgressRoute, ...] = ()) -> EgressPlan:
         egress_network=f"bot-bottle-egress-{SLUG}",
         mitmproxy_ca_host_path=STATE / "egress-ca" / "mitmproxy-ca.pem",
         mitmproxy_ca_cert_only_host_path=STATE / "egress-ca" / "ca.pem",
+        canary="fake-canary-value" if canary else "",
+        canary_env="CANON_ALPHA_SECRET" if canary else "",
     )
 
 
@@ -112,6 +118,7 @@ def _plan(
     with_git: bool = False,
     with_egress: bool = False,
     supervise: bool = False,
+    canary: bool = False,
 ) -> DockerBottlePlan:
     """Build a fully-resolved DockerBottlePlan. Toggles cover the
     matrix the renderer's conditional-service logic branches on."""
@@ -150,7 +157,7 @@ def _plan(
         slug=SLUG,
         forwarded_env={"CLAUDE_CODE_OAUTH_TOKEN": "x"},
         git_gate_plan=_git_gate_plan(upstreams),
-        egress_plan=_egress_plan(routes),
+        egress_plan=_egress_plan(routes, canary=canary),
         supervise_plan=_supervise_plan() if supervise else None,
         use_runsc=False,
         agent_provision=AgentProvisionPlan(
@@ -375,6 +382,20 @@ class TestSidecarBundleShape(unittest.TestCase):
         env_strings = sc["environment"]
         self.assertNotIn("EGRESS_TOKEN_0", env_strings)
 
+    def test_canary_env_registered_as_sensitive_in_sidecar(self):
+        sc = self._render(canary=True)["services"]["sidecars"]
+        env_strings = sc["environment"]
+        self.assertIn("CANON_ALPHA_SECRET=fake-canary-value", env_strings)
+        self.assertIn(
+            "BOT_BOTTLE_SENSITIVE_PREFIXES=CANON_ALPHA_SECRET",
+            env_strings,
+        )
+
+    def test_canary_env_visible_to_agent(self):
+        agent = self._render(canary=True)["services"]["agent"]
+        env_strings = agent["environment"]
+        self.assertIn("CANON_ALPHA_SECRET=fake-canary-value", env_strings)
+
     def test_supervise_env_present_when_active(self):
         sc = self._render(supervise=True)["services"]["sidecars"]
         env_strings = sc["environment"]

tests/unit/test_dlp_detectors.py

@@ -1,18 +1,23 @@
 """Unit: DLP detectors (PRD 0053).
 
-Tests for token pattern scanning, known secret detection, and
-naive prompt injection detection."""
+Tests for token pattern scanning, known secret detection, fragmentation-
+resistant matching, entropy scoring, and naive prompt injection detection."""
 
 import base64
 import gzip
 import unittest
 
 from bot_bottle.dlp_detectors import (
+    ENTROPY_BLOCK_THRESHOLD,
+    PARTIAL_MATCH_MIN_LEN,
     REDACT,
+    _alnum_projection,
     _encoded_variants,
     _normalize_text,
+    _shannon_entropy,
     redact_tokens,
     scan_crlf_injection,
+    scan_entropy,
     scan_known_secrets,
     scan_naive_injection,
     scan_token_patterns,
@@ -502,6 +507,191 @@ class TestStripCrlf(unittest.TestCase):
         from bot_bottle.dlp_detectors import strip_crlf
         self.assertEqual("/api/v1/data?q=hello", strip_crlf("/api/v1/data?q=hello"))
 
+class TestAlnumProjection(unittest.TestCase):
+    def test_alphanumeric_unchanged(self):
+        self.assertEqual("abc123XYZ", _alnum_projection("abc123XYZ"))
+
+    def test_strips_hyphens(self):
+        self.assertEqual("mysecretvalue", _alnum_projection("my-secret-value"))
+
+    def test_strips_spaces(self):
+        self.assertEqual("mysecretvalue", _alnum_projection("my secret value"))
+
+    def test_strips_dots_and_underscores(self):
+        self.assertEqual("mysecretvalue", _alnum_projection("my.secret_value"))
+
+    def test_empty_string(self):
+        self.assertEqual("", _alnum_projection(""))
+
+    def test_all_special_chars(self):
+        self.assertEqual("", _alnum_projection("!@#$%^&*()"))
+
+
+class TestFragmentationResistantMatching(unittest.TestCase):
+    """scan_known_secrets catches separator-injection and partial-substring evasion."""
+
+    # Secrets long enough that their alnum projections are ≥ 8 chars.
+    SECRET = "supersecrettoken99"
+    ENV = {"EGRESS_TOKEN_0": SECRET}
+
+    def test_exact_match_still_works(self):
+        result = scan_known_secrets(f"key={self.SECRET}", env=self.ENV)
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertEqual("block", result.severity)
+
+    def test_separator_injection_blocked(self):
+        # Hyphens inserted between chars of the secret.
+        fragmented = "-".join(self.SECRET)
+        result = scan_known_secrets(f"data={fragmented}", env=self.ENV)
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertEqual("block", result.severity)
+        self.assertIn("separator injection", result.reason)
+
+    def test_space_separator_blocked(self):
+        fragmented = " ".join(self.SECRET)
+        result = scan_known_secrets(f"body: {fragmented}", env=self.ENV)
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertIn("separator injection", result.reason)
+
+    def test_partial_substring_blocked(self):
+        # First PARTIAL_MATCH_MIN_LEN alnum chars of the secret, no separators.
+        partial = _alnum_projection(self.SECRET)[:PARTIAL_MATCH_MIN_LEN]
+        result = scan_known_secrets(f"x={partial}&y=other", env=self.ENV)
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertEqual("block", result.severity)
+        self.assertIn("partial match", result.reason)
+
+    def test_short_secret_skips_projection(self):
+        # Secrets shorter than _ALNUM_MIN_LEN in alnum projection are not
+        # fragmentation-checked (too many false positives).
+        short_env = {"EGRESS_TOKEN_0": "abc"}
+        # "a b c" has alnum projection "abc" (3 chars, < 8); should not block.
+        self.assertIsNone(scan_known_secrets("a b c", env=short_env))
+
+    def test_clean_text_not_blocked(self):
+        self.assertIsNone(scan_known_secrets("nothing to see here", env=self.ENV))
+
+    def test_sensitive_prefixes_param_extra_prefix(self):
+        env = {"MY_CRED_0": self.SECRET, "IGNORED": "other"}
+        result = scan_known_secrets(
+            f"key={self.SECRET}",
+            env=env,
+            sensitive_prefixes=("MY_CRED_",),
+        )
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertIn("MY_CRED_0", result.reason)
+
+    def test_sensitive_prefixes_default_only_egress_token(self):
+        # A value under a non-EGRESS_TOKEN_ key is ignored with default prefixes.
+        env = {"MY_CRED_0": self.SECRET}
+        self.assertIsNone(scan_known_secrets(f"key={self.SECRET}", env=env))
+
+    def test_canary_prefix_detected(self):
+        canary_value = "canary-fake-secret-value-xyz"
+        env = {"CANON_ALPHA_SECRET": canary_value}
+        result = scan_known_secrets(
+            f"x={canary_value}",
+            env=env,
+            sensitive_prefixes=("CANON_ALPHA_SECRET",),
+        )
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertIn("CANON_ALPHA_SECRET", result.reason)
+
+
+class TestRedactTokensBroadenedPrefixes(unittest.TestCase):
+    SECRET = "my-provisioned-secret"
+
+    def test_default_redacts_egress_token(self):
+        env = {"EGRESS_TOKEN_0": self.SECRET}
+        out = redact_tokens(f"val={self.SECRET}", env=env)
+        self.assertNotIn(self.SECRET, out)
+        self.assertIn(REDACT, out)
+
+    def test_extra_prefix_redacted(self):
+        env = {"MY_SECRET_KEY": self.SECRET}
+        out = redact_tokens(
+            f"val={self.SECRET}",
+            env=env,
+            sensitive_prefixes=("MY_SECRET_",),
+        )
+        self.assertNotIn(self.SECRET, out)
+        self.assertIn(REDACT, out)
+
+    def test_non_matching_prefix_not_redacted(self):
+        env = {"MY_SECRET_KEY": self.SECRET}
+        out = redact_tokens(f"val={self.SECRET}", env=env)
+        # Default prefixes only include EGRESS_TOKEN_ → secret not redacted
+        self.assertIn(self.SECRET, out)
+
+
+class TestShannonEntropy(unittest.TestCase):
+    def test_empty_string_zero(self):
+        self.assertEqual(0.0, _shannon_entropy(""))
+
+    def test_single_char_zero(self):
+        self.assertEqual(0.0, _shannon_entropy("aaaaaa"))
+
+    def test_two_equal_chars_one_bit(self):
+        self.assertAlmostEqual(1.0, _shannon_entropy("abababab"), places=10)
+
+    def test_high_entropy_random_like(self):
+        # Uniform 64-char string over 64 distinct symbols has entropy 6 bits.
+        import string
+        alphabet = (string.ascii_letters + string.digits + "+/")[:64]
+        text = alphabet  # each char appears exactly once
+        self.assertAlmostEqual(6.0, _shannon_entropy(text), places=10)
+
+
+class TestScanEntropy(unittest.TestCase):
+    def test_empty_returns_none(self):
+        self.assertIsNone(scan_entropy(""))
+
+    def test_low_entropy_returns_none(self):
+        # Highly repetitive text has low entropy.
+        self.assertIsNone(scan_entropy("a" * 200))
+
+    def test_high_entropy_warns(self):
+        # Build a 64-char string with entropy > ENTROPY_BLOCK_THRESHOLD.
+        # Use all 64 distinct printable chars to maximise entropy (~6 bits).
+        import string
+        alphabet = (string.ascii_letters + string.digits + "+/")[:64]
+        result = scan_entropy(alphabet, threshold=ENTROPY_BLOCK_THRESHOLD)
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertEqual("warn", result.severity)
+        self.assertIn("high-entropy", result.reason)
+
+    def test_never_blocks(self):
+        import string
+        alphabet = (string.ascii_letters + string.digits + "+/")[:64]
+        result = scan_entropy(alphabet)
+        # scan_entropy is warn-only; it must never return severity="block".
+        if result is not None:
+            self.assertNotEqual("block", result.severity)
+
+    def test_location_in_result(self):
+        import string
+        alphabet = (string.ascii_letters + string.digits + "+/")[:64]
+        result = scan_entropy(alphabet, location="authorization header")
+        if result is not None:
+            self.assertIn("authorization header", result.location)
+
+    def test_structured_json_no_warn(self):
+        # Typical JSON has low entropy and should not be flagged.
+        json_body = '{"status": "ok", "message": "hello world", "count": 42}'
+        self.assertIsNone(scan_entropy(json_body))
+
+    def test_short_text_below_window(self):
+        # Text shorter than the window: checked as one chunk.
+        # Use a uniform string to ensure it won't be flagged.
+        self.assertIsNone(scan_entropy("abcde", threshold=ENTROPY_BLOCK_THRESHOLD))
+
 
 if __name__ == "__main__":
     unittest.main()

tests/unit/test_egress.py

@@ -1,15 +1,21 @@
 """Unit: Egress route lift + routes.yaml render + token
 resolution (PRD 0017, PRD 0053)."""
 
+import tempfile
 import unittest
+from pathlib import Path
 
 from bot_bottle.egress import (
     CODEX_HOST_CREDENTIAL_TOKEN_REF,
+    Egress,
+    EgressPlan,
     EgressRoute,
+    egress_agent_env_entries,
     egress_manifest_routes,
     egress_render_routes,
     egress_resolve_token_values,
     egress_routes_for_bottle,
+    egress_sidecar_env_entries,
     egress_token_env_map,
 )
 from bot_bottle.log import Die
@@ -443,5 +449,119 @@ class TestResolveTokenValues(unittest.TestCase):
         self.assertEqual({"EGRESS_TOKEN_0": "codex-access-token"}, out)
 
 
+class TestCanaryGeneration(unittest.TestCase):
+    """Egress.prepare() generates a unique canary token per session."""
+
+    def _bottle_obj(self):
+        return ManifestIndex.from_json_obj({
+            "bottles": {"dev": {"egress": {"routes": []}}},
+            "agents": {"demo": {"skills": [], "prompt": "", "bottle": "dev"}},
+        }).bottles["dev"]
+
+    def _make_plan(self) -> EgressPlan:
+        # Use a concrete no-op subclass so we can call prepare() without
+        # a real backend.
+        class _TestEgress(Egress):
+            pass
+
+        e = _TestEgress()
+        with tempfile.TemporaryDirectory() as td:
+            return e.prepare(self._bottle_obj(), "test-slug", Path(td))
+
+    def test_canary_is_non_empty(self):
+        plan = self._make_plan()
+        self.assertIsInstance(plan.canary, str)
+        self.assertGreater(len(plan.canary), 0)
+        self.assertRegex(plan.canary_env, r"^[A-Z]+_[A-Z]+_SECRET$")
+
+    def test_canary_is_unique_per_session(self):
+        with tempfile.TemporaryDirectory() as td:
+            bottle = self._bottle_obj()
+
+            class _TestEgress(Egress):
+                pass
+
+            e = _TestEgress()
+            plan_a = e.prepare(bottle, "slug-a", Path(td))
+            plan_b = e.prepare(bottle, "slug-b", Path(td))
+        self.assertNotEqual(plan_a.canary, plan_b.canary)
+
+    def test_canary_detected_by_scan_known_secrets(self):
+        from bot_bottle.dlp_detectors import scan_known_secrets
+
+        plan = self._make_plan()
+        env = {plan.canary_env: plan.canary}
+        result = scan_known_secrets(
+            f"exfil={plan.canary}",
+            env=env,
+            sensitive_prefixes=(plan.canary_env,),
+        )
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertEqual("block", result.severity)
+        self.assertIn(plan.canary_env, result.reason)
+
+    def test_egress_plan_canary_field_default_empty(self):
+        # Verify EgressPlan can be constructed with an empty canary (backward compat).
+        from pathlib import Path
+        plan = EgressPlan(
+            slug="s",
+            routes_path=Path("/tmp/r.yaml"),
+            routes=(),
+            token_env_map={},
+        )
+        self.assertEqual("", plan.canary)
+        self.assertEqual("", plan.canary_env)
+
+
+class TestEgressEnvEntries(unittest.TestCase):
+    def test_sidecar_entries_include_route_tokens_and_canary_scan_prefix(self):
+        plan = EgressPlan(
+            slug="s",
+            routes_path=Path("/tmp/r.yaml"),
+            routes=(EgressRoute(host="api.example"),),
+            token_env_map={"EGRESS_TOKEN_1": "T1", "EGRESS_TOKEN_0": "T0"},
+            canary="fake-canary-value",
+            canary_env="CANON_ALPHA_SECRET",
+        )
+
+        self.assertEqual(
+            (
+                "EGRESS_TOKEN_0",
+                "EGRESS_TOKEN_1",
+                "CANON_ALPHA_SECRET=fake-canary-value",
+                "BOT_BOTTLE_SENSITIVE_PREFIXES=CANON_ALPHA_SECRET",
+            ),
+            egress_sidecar_env_entries(plan),
+        )
+
+    def test_agent_entries_include_only_canary_bait(self):
+        plan = EgressPlan(
+            slug="s",
+            routes_path=Path("/tmp/r.yaml"),
+            routes=(),
+            token_env_map={},
+            canary="fake-canary-value",
+            canary_env="CANON_ALPHA_SECRET",
+        )
+
+        self.assertEqual(
+            ("CANON_ALPHA_SECRET=fake-canary-value",),
+            egress_agent_env_entries(plan),
+        )
+
+    def test_canary_entries_omitted_when_name_missing(self):
+        plan = EgressPlan(
+            slug="s",
+            routes_path=Path("/tmp/r.yaml"),
+            routes=(),
+            token_env_map={},
+            canary="fake-canary-value",
+        )
+
+        self.assertEqual((), egress_sidecar_env_entries(plan))
+        self.assertEqual((), egress_agent_env_entries(plan))
+
+
 if __name__ == "__main__":
     unittest.main()

tests/unit/test_egress_addon_core.py

@@ -1273,6 +1273,109 @@ class TestBuildTokenAllowPayload(unittest.TestCase):
         result = ScanResult(severity="block", reason="r", matched="x")
         payload = build_token_allow_payload("h", "GET", "/", result)
         self.assertNotIn("context:", payload)
+class TestScanOutboundEnhanced(unittest.TestCase):
+    """scan_outbound changes: binary decode, entropy detector,
+    broadened known-value prefixes, fragmentation resistance."""
+
+    _ROUTE = Route(host="api.example.com")
+    _ROUTE_ENTROPY = Route(
+        host="api.example.com",
+        outbound_detectors=("entropy",),
+    )
+
+    def test_binary_body_latin1_decode_finds_ascii_secret(self):
+        # Body contains valid ASCII secret surrounded by non-UTF-8 bytes.
+        secret = "supersecrettoken99"
+        env = {"EGRESS_TOKEN_0": secret}
+        # Wrap the secret in bytes that are invalid UTF-8.
+        body = b"\x80\x81" + secret.encode("ascii") + b"\xff"
+        result = scan_outbound(self._ROUTE, body, env)
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertEqual("block", result.severity)
+
+    def test_binary_body_valid_utf8_decoded_correctly(self):
+        env = {"EGRESS_TOKEN_0": "mysecret"}
+        # Valid UTF-8 body — should be decoded as UTF-8, not latin-1.
+        body = "clean body with mysecret".encode("utf-8")
+        result = scan_outbound(self._ROUTE, body, env)
+        self.assertIsNotNone(result)
+
+    def test_entropy_detector_off_by_default(self):
+        import string
+        # High-entropy content should NOT warn if the route has no entropy detector.
+        alphabet = (string.ascii_letters + string.digits + "+/")[:64]
+        result = scan_outbound(self._ROUTE, alphabet, {})
+        self.assertIsNone(result)
+
+    def test_entropy_detector_warns_when_enabled(self):
+        import string
+        alphabet = (string.ascii_letters + string.digits + "+/")[:64]
+        result = scan_outbound(self._ROUTE_ENTROPY, alphabet, {})
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertEqual("warn", result.severity)
+
+    def test_bot_bottle_sensitive_prefixes_env_var(self):
+        # When the sidecar env contains BOT_BOTTLE_SENSITIVE_PREFIXES,
+        # scan_outbound should scan those additional prefixes.
+        secret = "extra-sensitive-value-abc"
+        env = {
+            "MY_CRED_KEY": secret,
+            "BOT_BOTTLE_SENSITIVE_PREFIXES": "MY_CRED_",
+        }
+        result = scan_outbound(self._ROUTE, f"x={secret}", env)
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertEqual("block", result.severity)
+
+    def test_bot_bottle_sensitive_prefixes_multiple(self):
+        secret = "my-api-key-value-xyz"
+        env = {
+            "ANTHROPIC_API_0": secret,
+            "BOT_BOTTLE_SENSITIVE_PREFIXES": "ANTHROPIC_API_,OTHER_",
+        }
+        result = scan_outbound(self._ROUTE, f"auth={secret}", env)
+        self.assertIsNotNone(result)
+
+    def test_canary_detected_via_random_secret_env_name(self):
+        # The fake secret uses a randomized env name that the sidecar marks
+        # as sensitive through BOT_BOTTLE_SENSITIVE_PREFIXES.
+        canary = "canaryvalue12345abcdef"
+        env = {
+            "CANON_ALPHA_SECRET": canary,
+            "BOT_BOTTLE_SENSITIVE_PREFIXES": "CANON_ALPHA_SECRET",
+        }
+        result = scan_outbound(self._ROUTE, f"data={canary}", env)
+        self.assertIsNotNone(result)
+        assert result is not None
+        self.assertEqual("block", result.severity)
+        self.assertIn("CANON_ALPHA_SECRET", result.reason)
+
+    def test_fragmented_canary_blocked(self):
+        # Canary with separators injected is still caught.
+        canary = "supersecretcanary99"
+        env = {
+            "CANON_ALPHA_SECRET": canary,
+            "BOT_BOTTLE_SENSITIVE_PREFIXES": "CANON_ALPHA_SECRET",
+        }
+        fragmented = "-".join(canary)
+        result = scan_outbound(self._ROUTE, f"x={fragmented}", env)
+        self.assertIsNotNone(result)
+
+
+class TestOutboundDetectorNames(unittest.TestCase):
+    def test_entropy_in_outbound_detector_names(self):
+        from bot_bottle.egress_addon_core import OUTBOUND_DETECTOR_NAMES
+        self.assertIn("entropy", OUTBOUND_DETECTOR_NAMES)
+
+    def test_known_secrets_in_outbound_detector_names(self):
+        from bot_bottle.egress_addon_core import OUTBOUND_DETECTOR_NAMES
+        self.assertIn("known_secrets", OUTBOUND_DETECTOR_NAMES)
+
+    def test_token_patterns_in_outbound_detector_names(self):
+        from bot_bottle.egress_addon_core import OUTBOUND_DETECTOR_NAMES
+        self.assertIn("token_patterns", OUTBOUND_DETECTOR_NAMES)
 
 
 if __name__ == "__main__":

tests/unit/test_macos_container_launch.py

@@ -30,6 +30,7 @@ def _plan(
     supervise: bool = False,
     agent_git_gate_url: str = "",
     agent_supervise_url: str = "",
+    canary: bool = False,
 ) -> MacosContainerBottlePlan:
     routes_path = stage_dir / "routes.yaml"
     routes_path.write_text("routes: []\n", encoding="utf-8")
@@ -42,6 +43,8 @@ def _plan(
         routes_path=routes_path,
         routes=("route",),
         token_env_map={"EGRESS_TOKEN_0": "HOST_TOKEN"},
+        canary="fake-canary-value" if canary else "",
+        canary_env="CANON_ALPHA_SECRET" if canary else "",
     )
     if git:
         key_path = stage_dir / "origin-key"
@@ -138,6 +141,26 @@ class TestMacosContainerLaunchArgv(unittest.TestCase):
             argv,
         )
 
+    def test_sidecar_argv_registers_canary_env_as_sensitive(self):
+        plan = _plan(stage_dir=self.stage_dir, canary=True)
+        argv = launch._sidecar_run_argv(
+            plan,
+            "bot-bottle-sidecars-dev-abc",
+            "bot-bottle-net-dev-abc",
+            "bot-bottle-egress-dev-abc",
+        )
+        self.assertIn("CANON_ALPHA_SECRET=fake-canary-value", argv)
+        self.assertIn("BOT_BOTTLE_SENSITIVE_PREFIXES=CANON_ALPHA_SECRET", argv)
+
+    def test_agent_argv_receives_canary_env(self):
+        plan = _plan(stage_dir=self.stage_dir, canary=True)
+        argv = launch._agent_run_argv(
+            plan,
+            "bot-bottle-net-dev-abc",
+            "192.0.2.10",
+        )
+        self.assertIn("CANON_ALPHA_SECRET=fake-canary-value", argv)
+
     def test_agent_env_points_proxy_at_sidecar_ip(self):
         plan = _plan(
             stage_dir=self.stage_dir,
@@ -271,7 +294,7 @@ def _build_plan(stage_dir: Path) -> MacosContainerBottlePlan:
         manifest=_MANIFEST,
         stage_dir=stage_dir,
         git_gate_plan=cast(GitGatePlan, SimpleNamespace(upstreams=())),
-        egress_plan=cast(EgressPlan, SimpleNamespace()),
+        egress_plan=cast(EgressPlan, SimpleNamespace(canary="")),
         supervise_plan=None,
         agent_provision=AgentProvisionPlan(
             template="claude",

tests/unit/test_smolmachines_provision.py

@@ -26,9 +26,7 @@ from bot_bottle.backend.smolmachines.bottle import SmolmachinesBottle
 from bot_bottle.backend.smolmachines.bottle_plan import (
     SmolmachinesBottlePlan,
 )
-# from bot_bottle.backend.smolmachines.provision import (
-#     workspace as _workspace,
-# )
+from bot_bottle.backend.smolmachines import launch as _launch
 from bot_bottle.backend.smolmachines.launch import _bundle_launch_spec
 from bot_bottle.backend.util import AGENT_CA_PATH
 from bot_bottle.egress import EgressPlan, EgressRoute
@@ -86,6 +84,7 @@ def _plan(
     stage_dir: Path | None = None,
     egress_routes: tuple[EgressRoute, ...] = (),
     egress_ca_path: Path = Path(),
+    canary: bool = False,
     supervise: bool = False,
     bundle_ip: str = "192.168.50.2",
     agent_git_gate_host: str = "127.0.0.1:55555",
@@ -156,6 +155,8 @@ def _plan(
             routes=egress_routes,
             token_env_map={},
             mitmproxy_ca_cert_only_host_path=egress_ca_path,
+            canary="fake-canary-value" if canary else "",
+            canary_env="CANON_ALPHA_SECRET" if canary else "",
         ),
         supervise_plan=supervise_plan,
         agent_git_gate_host=agent_git_gate_host,
@@ -411,6 +412,31 @@ class TestBundleLaunchSpec(unittest.TestCase):
         self.assertIn(9420, spec.ports_to_publish)
         self.assertNotIn(9418, spec.ports_to_publish)
 
+    def test_canary_env_registered_as_sensitive_in_bundle(self):
+        plan = _plan(canary=True)
+
+        spec = _bundle_launch_spec(plan, "net", "127.0.0.16")
+
+        self.assertIn("CANON_ALPHA_SECRET=fake-canary-value", spec.environment)
+        self.assertIn(
+            "BOT_BOTTLE_SENSITIVE_PREFIXES=CANON_ALPHA_SECRET",
+            spec.environment,
+        )
+
+    def test_canary_env_visible_to_smolvm_guest(self):
+        plan = _plan(canary=True)
+        with patch.object(
+            _launch._bundle,
+            "bundle_host_port",
+            return_value="65000",
+        ):
+            stamped = _launch._discover_urls(plan, "127.0.0.16")
+
+        self.assertEqual(
+            "fake-canary-value",
+            stamped.guest_env["CANON_ALPHA_SECRET"],
+        )
+
 
 class TestProvisionGitUser(unittest.TestCase):
     """`provision_git` runs `git config --global` inside the